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Update. 

1997-04-02 16:55  Ulrich Drepper  <drepper@cygnus.com>

	* manual/socket.texi: Document behaviour of inet_ntoa in multi-
	threaded programs.
	* manual/stdio.texi: Change wording for snprintf description a bit.
	Correct typo in example.
	* manual/lang.texi: Add documentation of __va_copy.

	* Makefile: Add rule to easily generate dir-add.texi file.
	* manual/Makefile: Likewise.

	* manual/arith.texi: Add description of lldiv_t, lldiv, and atoll.
	Change description of strtoll and strtoull to make clear these
	are the preferred names.
	Describe `inf', `inifinity', `nan', `nan(...)' inputs for strtod
	and friends.
	Change references to HUGE_VALf and HUGE_VALl to HUGE_VALF and
	HUGE_VALL.

	* sysdeps/libm-ieee754/s_nan.c: Use strtod if parameter is not empty
	* sysdeps/libm-ieee754/s_nanl.c: Likewise.
This commit is contained in:
Ulrich Drepper 1997-04-02 22:06:24 +00:00
parent 22d57dd369
commit fe7bdd630f
13 changed files with 162 additions and 3406 deletions
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23
ChangeLog
View File

@ -1,3 +1,22 @@
1997-04-02 16:55 Ulrich Drepper <drepper@cygnus.com>
* manual/socket.texi: Document behaviour of inet_ntoa in multi-
threaded programs.
* manual/stdio.texi: Change wording for snprintf description a bit.
Correct typo in example.
* manual/lang.texi: Add documentation of __va_copy.
* Makefile: Add rule to easily generate dir-add.texi file.
* manual/Makefile: Likewise.
* manual/arith.texi: Add description of lldiv_t, lldiv, and atoll.
Change description of strtoll and strtoull to make clear these
are the preferred names.
Describe `inf', `inifinity', `nan', `nan(...)' inputs for strtod
and friends.
Change references to HUGE_VALf and HUGE_VALl to HUGE_VALF and
HUGE_VALL.
1997-04-02 16:28 Ulrich Drepper <drepper@cygnus.com>
* grp/fgetgrent.c: Don't use fixed buffer length. Allow dynamic
@ -31,10 +50,10 @@
* wcsmbs/wcstof.c: Likewise.
* wcsmbs/wcstold.c: Likewise.
* sysdeps/libm-ieee754/s_nan.c: Use strtod is parameter is not empty
* sysdeps/libm-ieee754/s_nan.c: Use strtod if parameter is not empty
string.
* sysdeps/libm-ieee754/s_nanf.c: Likewise.
* sysdeps/libm-ieee754/s_nanld.c: Likewise.
* sysdeps/libm-ieee754/s_nanl.c: Likewise.
1997-04-02 13:56 Ulrich Drepper <drepper@cygnus.com>

2
Makefile
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@ -313,6 +313,8 @@ makeinfo --no-validate --no-warn --no-headers $< -o $@
endef
INSTALL: manual/maint.texi; $(format-me)
NOTES: manual/creature.texi; $(format-me)
manual/dir-add.texi:
$(MAKE) $(PARALLELMFLAGS) -C $(@D) $(@F)
rpm/%: subdir_distinfo
$(MAKE) $(PARALLELMFLAGS) -C $(@D) subdirs='$(subdirs)' $(@F)

540
manual/=copying.texinfo
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@ -1,540 +0,0 @@
@comment This material was copied from /gd/gnu/doc/lgpl.texinfo.
@node Copying, Concept Index, Maintenance, Top
@appendix GNU GENERAL PUBLIC LICENSE
@center Version 2, June 1991
@display
Copyright @copyright{} 1991 Free Software Foundation, Inc.
675 Mass Ave, Cambridge, MA 02139, USA
Everyone is permitted to copy and distribute verbatim copies
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[This is the first released version of the library GPL. It is
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@end display
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That's all there is to it!

414
manual/=float.texinfo
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@ -1,414 +0,0 @@
@node Floating-Point Limits
@chapter Floating-Point Limits
@pindex <float.h>
@cindex floating-point number representation
@cindex representation of floating-point numbers
Because floating-point numbers are represented internally as approximate
quantities, algorithms for manipulating floating-point data often need
to be parameterized in terms of the accuracy of the representation.
Some of the functions in the C library itself need this information; for
example, the algorithms for printing and reading floating-point numbers
(@pxref{I/O on Streams}) and for calculating trigonometric and
irrational functions (@pxref{Mathematics}) use information about the
underlying floating-point representation to avoid round-off error and
loss of accuracy. User programs that implement numerical analysis
techniques also often need to be parameterized in this way in order to
minimize or compute error bounds.
The specific representation of floating-point numbers varies from
machine to machine. The GNU C Library defines a set of parameters which
characterize each of the supported floating-point representations on a
particular system.
@menu
* Floating-Point Representation:: Definitions of terminology.
* Floating-Point Parameters:: Descriptions of the library facilities.
* IEEE Floating-Point:: An example of a common representation.
@end menu
@node Floating-Point Representation
@section Floating-Point Representation
This section introduces the terminology used to characterize the
representation of floating-point numbers.
You are probably already familiar with most of these concepts in terms
of scientific or exponential notation for floating-point numbers. For
example, the number @code{123456.0} could be expressed in exponential
notation as @code{1.23456e+05}, a shorthand notation indicating that the
mantissa @code{1.23456} is multiplied by the base @code{10} raised to
power @code{5}.
More formally, the internal representation of a floating-point number
can be characterized in terms of the following parameters:
@itemize @bullet
@item
The @dfn{sign} is either @code{-1} or @code{1}.
@cindex sign (of floating-point number)
@item
The @dfn{base} or @dfn{radix} for exponentiation; an integer greater
than @code{1}. This is a constant for the particular representation.
@cindex base (of floating-point number)
@cindex radix (of floating-point number)
@item
The @dfn{exponent} to which the base is raised. The upper and lower
bounds of the exponent value are constants for the particular
representation.
@cindex exponent (of floating-point number)
Sometimes, in the actual bits representing the floating-point number,
the exponent is @dfn{biased} by adding a constant to it, to make it
always be represented as an unsigned quantity. This is only important
if you have some reason to pick apart the bit fields making up the
floating-point number by hand, which is something for which the GNU
library provides no support. So this is ignored in the discussion that
follows.
@cindex bias, in exponent (of floating-point number)
@item
The value of the @dfn{mantissa} or @dfn{significand}, which is an
unsigned quantity.
@cindex mantissa (of floating-point number)
@cindex significand (of floating-point number)
@item
The @dfn{precision} of the mantissa. If the base of the representation
is @var{b}, then the precision is the number of base-@var{b} digits in
the mantissa. This is a constant for the particular representation.
Many floating-point representations have an implicit @dfn{hidden bit} in
the mantissa. Any such hidden bits are counted in the precision.
Again, the GNU library provides no facilities for dealing with such low-level
aspects of the representation.
@cindex precision (of floating-point number)
@cindex hidden bit, in mantissa (of floating-point number)
@end itemize
The mantissa of a floating-point number actually represents an implicit
fraction whose denominator is the base raised to the power of the
precision. Since the largest representable mantissa is one less than
this denominator, the value of the fraction is always strictly less than
@code{1}. The mathematical value of a floating-point number is then the
product of this fraction; the sign; and the base raised to the exponent.
If the floating-point number is @dfn{normalized}, the mantissa is also
greater than or equal to the base raised to the power of one less
than the precision (unless the number represents a floating-point zero,
in which case the mantissa is zero). The fractional quantity is
therefore greater than or equal to @code{1/@var{b}}, where @var{b} is
the base.
@cindex normalized floating-point number
@node Floating-Point Parameters
@section Floating-Point Parameters
@strong{Incomplete:} This section needs some more concrete examples
of what these parameters mean and how to use them in a program.
These macro definitions can be accessed by including the header file
@file{<float.h>} in your program.
Macro names starting with @samp{FLT_} refer to the @code{float} type,
while names beginning with @samp{DBL_} refer to the @code{double} type
and names beginning with @samp{LDBL_} refer to the @code{long double}
type. (In implementations that do not support @code{long double} as
a distinct data type, the values for those constants are the same
as the corresponding constants for the @code{double} type.)@refill
Note that only @code{FLT_RADIX} is guaranteed to be a constant
expression, so the other macros listed here cannot be reliably used in
places that require constant expressions, such as @samp{#if}
preprocessing directives and array size specifications.
Although the @w{ISO C} standard specifies minimum and maximum values for
most of these parameters, the GNU C implementation uses whatever
floating-point representations are supported by the underlying hardware.
So whether GNU C actually satisfies the @w{ISO C} requirements depends on
what machine it is running on.
@comment float.h
@comment ISO
@defvr Macro FLT_ROUNDS
This value characterizes the rounding mode for floating-point addition.
The following values indicate standard rounding modes:
@table @code
@item -1
The mode is indeterminable.
@item 0
Rounding is towards zero.
@item 1
Rounding is to the nearest number.
@item 2
Rounding is towards positive infinity.
@item 3
Rounding is towards negative infinity.
@end table
@noindent
Any other value represents a machine-dependent nonstandard rounding
mode.
@end defvr
@comment float.h
@comment ISO
@defvr Macro FLT_RADIX
This is the value of the base, or radix, of exponent representation.
This is guaranteed to be a constant expression, unlike the other macros
described in this section.
@end defvr
@comment float.h
@comment ISO
@defvr Macro FLT_MANT_DIG
This is the number of base-@code{FLT_RADIX} digits in the floating-point
mantissa for the @code{float} data type.
@end defvr
@comment float.h
@comment ISO
@defvr Macro DBL_MANT_DIG
This is the number of base-@code{FLT_RADIX} digits in the floating-point
mantissa for the @code{double} data type.
@end defvr
@comment float.h
@comment ISO
@defvr Macro LDBL_MANT_DIG
This is the number of base-@code{FLT_RADIX} digits in the floating-point
mantissa for the @code{long double} data type.
@end defvr
@comment float.h
@comment ISO
@defvr Macro FLT_DIG
This is the number of decimal digits of precision for the @code{float}
data type. Technically, if @var{p} and @var{b} are the precision and
base (respectively) for the representation, then the decimal precision
@var{q} is the maximum number of decimal digits such that any floating
point number with @var{q} base 10 digits can be rounded to a floating
point number with @var{p} base @var{b} digits and back again, without
change to the @var{q} decimal digits.
The value of this macro is guaranteed to be at least @code{6}.
@end defvr
@comment float.h
@comment ISO
@defvr Macro DBL_DIG
This is similar to @code{FLT_DIG}, but is for the @code{double} data
type. The value of this macro is guaranteed to be at least @code{10}.
@end defvr
@comment float.h
@comment ISO
@defvr Macro LDBL_DIG
This is similar to @code{FLT_DIG}, but is for the @code{long double}
data type. The value of this macro is guaranteed to be at least
@code{10}.
@end defvr
@comment float.h
@comment ISO
@defvr Macro FLT_MIN_EXP
This is the minimum negative integer such that the mathematical value
@code{FLT_RADIX} raised to this power minus 1 can be represented as a
normalized floating-point number of type @code{float}. In terms of the
actual implementation, this is just the smallest value that can be
represented in the exponent field of the number.
@end defvr
@comment float.h
@comment ISO
@defvr Macro DBL_MIN_EXP
This is similar to @code{FLT_MIN_EXP}, but is for the @code{double} data
type.
@end defvr
@comment float.h
@comment ISO
@defvr Macro LDBL_MIN_EXP
This is similar to @code{FLT_MIN_EXP}, but is for the @code{long double}
data type.
@end defvr
@comment float.h
@comment ISO
@defvr Macro FLT_MIN_10_EXP
This is the minimum negative integer such that the mathematical value
@code{10} raised to this power minus 1 can be represented as a
normalized floating-point number of type @code{float}. This is
guaranteed to be no greater than @code{-37}.
@end defvr
@comment float.h
@comment ISO
@defvr Macro DBL_MIN_10_EXP
This is similar to @code{FLT_MIN_10_EXP}, but is for the @code{double}
data type.
@end defvr
@comment float.h
@comment ISO
@defvr Macro LDBL_MIN_10_EXP
This is similar to @code{FLT_MIN_10_EXP}, but is for the @code{long
double} data type.
@end defvr
@comment float.h
@comment ISO
@defvr Macro FLT_MAX_EXP
This is the maximum negative integer such that the mathematical value
@code{FLT_RADIX} raised to this power minus 1 can be represented as a
floating-point number of type @code{float}. In terms of the actual
implementation, this is just the largest value that can be represented
in the exponent field of the number.
@end defvr
@comment float.h
@comment ISO
@defvr Macro DBL_MAX_EXP
This is similar to @code{FLT_MAX_EXP}, but is for the @code{double} data
type.
@end defvr
@comment float.h
@comment ISO
@defvr Macro LDBL_MAX_EXP
This is similar to @code{FLT_MAX_EXP}, but is for the @code{long double}
data type.
@end defvr
@comment float.h
@comment ISO
@defvr Macro FLT_MAX_10_EXP
This is the maximum negative integer such that the mathematical value
@code{10} raised to this power minus 1 can be represented as a
normalized floating-point number of type @code{float}. This is
guaranteed to be at least @code{37}.
@end defvr
@comment float.h
@comment ISO
@defvr Macro DBL_MAX_10_EXP
This is similar to @code{FLT_MAX_10_EXP}, but is for the @code{double}
data type.
@end defvr
@comment float.h
@comment ISO
@defvr Macro LDBL_MAX_10_EXP
This is similar to @code{FLT_MAX_10_EXP}, but is for the @code{long
double} data type.
@end defvr
@comment float.h
@comment ISO
@defvr Macro FLT_MAX
The value of this macro is the maximum representable floating-point
number of type @code{float}, and is guaranteed to be at least
@code{1E+37}.
@end defvr
@comment float.h
@comment ISO
@defvr Macro DBL_MAX
The value of this macro is the maximum representable floating-point
number of type @code{double}, and is guaranteed to be at least
@code{1E+37}.
@end defvr
@comment float.h
@comment ISO
@defvr Macro LDBL_MAX
The value of this macro is the maximum representable floating-point
number of type @code{long double}, and is guaranteed to be at least
@code{1E+37}.
@end defvr
@comment float.h
@comment ISO
@defvr Macro FLT_MIN
The value of this macro is the minimum normalized positive
floating-point number that is representable by type @code{float}, and is
guaranteed to be no more than @code{1E-37}.
@end defvr
@comment float.h
@comment ISO
@defvr Macro DBL_MIN
The value of this macro is the minimum normalized positive
floating-point number that is representable by type @code{double}, and
is guaranteed to be no more than @code{1E-37}.
@end defvr
@comment float.h
@comment ISO
@defvr Macro LDBL_MIN
The value of this macro is the minimum normalized positive
floating-point number that is representable by type @code{long double},
and is guaranteed to be no more than @code{1E-37}.
@end defvr
@comment float.h
@comment ISO
@defvr Macro FLT_EPSILON
This is the minimum positive floating-point number of type @code{float}
such that @code{1.0 + FLT_EPSILON != 1.0} is true. It's guaranteed to
be no greater than @code{1E-5}.
@end defvr
@comment float.h
@comment ISO
@defvr Macro DBL_EPSILON
This is similar to @code{FLT_EPSILON}, but is for the @code{double}
type. The maximum value is @code{1E-9}.
@end defvr
@comment float.h
@comment ISO
@defvr Macro LDBL_EPSILON
This is similar to @code{FLT_EPSILON}, but is for the @code{long double}
type. The maximum value is @code{1E-9}.
@end defvr
@node IEEE Floating Point
@section IEEE Floating Point
Here is an example showing how these parameters work for a common
floating point representation, specified by the @cite{IEEE Standard for
Binary Floating-Point Arithmetic (ANSI/IEEE Std 754-1985 or ANSI/IEEE
Std 854-1987)}.
The IEEE single-precision float representation uses a base of 2. There
is a sign bit, a mantissa with 23 bits plus one hidden bit (so the total
precision is 24 base-2 digits), and an 8-bit exponent that can represent
values in the range -125 to 128, inclusive.
So, for an implementation that uses this representation for the
@code{float} data type, appropriate values for the corresponding
parameters are:
@example
FLT_RADIX 2
FLT_MANT_DIG 24
FLT_DIG 6
FLT_MIN_EXP -125
FLT_MIN_10_EXP -37
FLT_MAX_EXP 128
FLT_MAX_10_EXP +38
FLT_MIN 1.17549435E-38F
FLT_MAX 3.40282347E+38F
FLT_EPSILON 1.19209290E-07F
@end example

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@node Representation Limits, System Configuration Limits, System Information, Top
@chapter Representation Limits
This chapter contains information about constants and parameters that
characterize the representation of the various integer and
floating-point types supported by the GNU C library.
@menu
* Integer Representation Limits:: Determining maximum and minimum
representation values of
various integer subtypes.
* Floating-Point Limits :: Parameters which characterize
supported floating-point
representations on a particular
system.
@end menu
@node Integer Representation Limits, Floating-Point Limits , , Representation Limits
@section Integer Representation Limits
@cindex integer representation limits
@cindex representation limits, integer
@cindex limits, integer representation
Sometimes it is necessary for programs to know about the internal
representation of various integer subtypes. For example, if you want
your program to be careful not to overflow an @code{int} counter
variable, you need to know what the largest representable value that
fits in an @code{int} is. These kinds of parameters can vary from
compiler to compiler and machine to machine. Another typical use of
this kind of parameter is in conditionalizing data structure definitions
with @samp{#ifdef} to select the most appropriate integer subtype that
can represent the required range of values.
Macros representing the minimum and maximum limits of the integer types
are defined in the header file @file{limits.h}. The values of these
macros are all integer constant expressions.
@pindex limits.h
@comment limits.h
@comment ISO
@deftypevr Macro int CHAR_BIT
This is the number of bits in a @code{char}, usually eight.
@end deftypevr
@comment limits.h
@comment ISO
@deftypevr Macro int SCHAR_MIN
This is the minimum value that can be represented by a @code{signed char}.
@end deftypevr
@comment limits.h
@comment ISO
@deftypevr Macro int SCHAR_MAX
This is the maximum value that can be represented by a @code{signed char}.
@end deftypevr
@comment limits.h
@comment ISO
@deftypevr Macro int UCHAR_MAX
This is the maximum value that can be represented by a @code{unsigned char}.
(The minimum value of an @code{unsigned char} is zero.)
@end deftypevr
@comment limits.h
@comment ISO
@deftypevr Macro int CHAR_MIN
This is the minimum value that can be represented by a @code{char}.
It's equal to @code{SCHAR_MIN} if @code{char} is signed, or zero
otherwise.
@end deftypevr
@comment limits.h
@comment ISO
@deftypevr Macro int CHAR_MAX
This is the maximum value that can be represented by a @code{char}.
It's equal to @code{SCHAR_MAX} if @code{char} is signed, or
@code{UCHAR_MAX} otherwise.
@end deftypevr
@comment limits.h
@comment ISO
@deftypevr Macro int SHRT_MIN
This is the minimum value that can be represented by a @code{signed
short int}. On most machines that the GNU C library runs on,
@code{short} integers are 16-bit quantities.
@end deftypevr
@comment limits.h
@comment ISO
@deftypevr Macro int SHRT_MAX
This is the maximum value that can be represented by a @code{signed
short int}.
@end deftypevr
@comment limits.h
@comment ISO
@deftypevr Macro int USHRT_MAX
This is the maximum value that can be represented by an @code{unsigned
short int}. (The minimum value of an @code{unsigned short int} is zero.)
@end deftypevr
@comment limits.h
@comment ISO
@deftypevr Macro int INT_MIN
This is the minimum value that can be represented by a @code{signed
int}. On most machines that the GNU C system runs on, an @code{int} is
a 32-bit quantity.
@end deftypevr
@comment limits.h
@comment ISO
@deftypevr Macro int INT_MAX
This is the maximum value that can be represented by a @code{signed
int}.
@end deftypevr
@comment limits.h
@comment ISO
@deftypevr Macro {unsigned int} UINT_MAX
This is the maximum value that can be represented by an @code{unsigned
int}. (The minimum value of an @code{unsigned int} is zero.)
@end deftypevr
@comment limits.h
@comment ISO
@deftypevr Macro {long int} LONG_MIN
This is the minimum value that can be represented by a @code{signed long
int}. On most machines that the GNU C system runs on, @code{long}
integers are 32-bit quantities, the same size as @code{int}.
@end deftypevr
@comment limits.h
@comment ISO
@deftypevr Macro {long int} LONG_MAX
This is the maximum value that can be represented by a @code{signed long
int}.
@end deftypevr
@comment limits.h
@comment ISO
@deftypevr Macro {unsigned long int} ULONG_MAX
This is the maximum value that can be represented by an @code{unsigned
long int}. (The minimum value of an @code{unsigned long int} is zero.)
@end deftypevr
@strong{Incomplete:} There should be corresponding limits for the GNU
C Compiler's @code{long long} type, too. (But they are not now present
in the header file.)
The header file @file{limits.h} also defines some additional constants
that parameterize various operating system and file system limits. These
constants are described in @ref{System Parameters} and @ref{File System
Parameters}.
@pindex limits.h
@node Floating-Point Limits , , Integer Representation Limits, Representation Limits
@section Floating-Point Limits
@cindex floating-point number representation
@cindex representation, floating-point number
@cindex limits, floating-point representation
Because floating-point numbers are represented internally as approximate
quantities, algorithms for manipulating floating-point data often need
to be parameterized in terms of the accuracy of the representation.
Some of the functions in the C library itself need this information; for
example, the algorithms for printing and reading floating-point numbers
(@pxref{I/O on Streams}) and for calculating trigonometric and
irrational functions (@pxref{Mathematics}) use information about the
underlying floating-point representation to avoid round-off error and
loss of accuracy. User programs that implement numerical analysis
techniques also often need to be parameterized in this way in order to
minimize or compute error bounds.
The specific representation of floating-point numbers varies from
machine to machine. The GNU C library defines a set of parameters which
characterize each of the supported floating-point representations on a
particular system.
@menu
* Floating-Point Representation:: Definitions of terminology.
* Floating-Point Parameters:: Descriptions of the library
facilities.
* IEEE Floating Point:: An example of a common
representation.
@end menu
@node Floating-Point Representation, Floating-Point Parameters, , Floating-Point Limits
@subsection Floating-Point Representation
This section introduces the terminology used to characterize the
representation of floating-point numbers.
You are probably already familiar with most of these concepts in terms
of scientific or exponential notation for floating-point numbers. For
example, the number @code{123456.0} could be expressed in exponential
notation as @code{1.23456e+05}, a shorthand notation indicating that the
mantissa @code{1.23456} is multiplied by the base @code{10} raised to
power @code{5}.
More formally, the internal representation of a floating-point number
can be characterized in terms of the following parameters:
@itemize @bullet
@item
The @dfn{sign} is either @code{-1} or @code{1}.
@cindex sign (of floating-point number)
@item
The @dfn{base} or @dfn{radix} for exponentiation; an integer greater
than @code{1}. This is a constant for the particular representation.
@cindex base (of floating-point number)
@cindex radix (of floating-point number)
@item
The @dfn{exponent} to which the base is raised. The upper and lower
bounds of the exponent value are constants for the particular
representation.
@cindex exponent (of floating-point number)
Sometimes, in the actual bits representing the floating-point number,
the exponent is @dfn{biased} by adding a constant to it, to make it
always be represented as an unsigned quantity. This is only important
if you have some reason to pick apart the bit fields making up the
floating-point number by hand, which is something for which the GNU
library provides no support. So this is ignored in the discussion that
follows.
@cindex bias (of floating-point number exponent)
@item
The value of the @dfn{mantissa} or @dfn{significand}, which is an
unsigned integer.
@cindex mantissa (of floating-point number)
@cindex significand (of floating-point number)
@item
The @dfn{precision} of the mantissa. If the base of the representation
is @var{b}, then the precision is the number of base-@var{b} digits in
the mantissa. This is a constant for the particular representation.
Many floating-point representations have an implicit @dfn{hidden bit} in
the mantissa. Any such hidden bits are counted in the precision.
Again, the GNU library provides no facilities for dealing with such low-level
aspects of the representation.
@cindex precision (of floating-point number)
@cindex hidden bit (of floating-point number mantissa)
@end itemize
The mantissa of a floating-point number actually represents an implicit
fraction whose denominator is the base raised to the power of the
precision. Since the largest representable mantissa is one less than
this denominator, the value of the fraction is always strictly less than
@code{1}. The mathematical value of a floating-point number is then the
product of this fraction; the sign; and the base raised to the exponent.
If the floating-point number is @dfn{normalized}, the mantissa is also
greater than or equal to the base raised to the power of one less
than the precision (unless the number represents a floating-point zero,
in which case the mantissa is zero). The fractional quantity is
therefore greater than or equal to @code{1/@var{b}}, where @var{b} is
the base.
@cindex normalized floating-point number
@node Floating-Point Parameters, IEEE Floating Point, Floating-Point Representation, Floating-Point Limits
@subsection Floating-Point Parameters
@strong{Incomplete:} This section needs some more concrete examples
of what these parameters mean and how to use them in a program.
These macro definitions can be accessed by including the header file
@file{float.h} in your program.
@pindex float.h
Macro names starting with @samp{FLT_} refer to the @code{float} type,
while names beginning with @samp{DBL_} refer to the @code{double} type
and names beginning with @samp{LDBL_} refer to the @code{long double}
type. (In implementations that do not support @code{long double} as
a distinct data type, the values for those constants are the same
as the corresponding constants for the @code{double} type.)@refill
@cindex @code{float} representation limits
@cindex @code{double} representation limits
@cindex @code{long double} representation limits
Of these macros, only @code{FLT_RADIX} is guaranteed to be a constant
expression. The other macros listed here cannot be reliably used in
places that require constant expressions, such as @samp{#if}
preprocessing directives or array size specifications.
Although the @w{ISO C} standard specifies minimum and maximum values for
most of these parameters, the GNU C implementation uses whatever
floating-point representations are supported by the underlying hardware.
So whether GNU C actually satisfies the @w{ISO C} requirements depends on
what machine it is running on.
@comment float.h
@comment ISO
@deftypevr Macro int FLT_ROUNDS
This value characterizes the rounding mode for floating-point addition.
The following values indicate standard rounding modes:
@table @code
@item -1
The mode is indeterminable.
@item 0
Rounding is towards zero.
@item 1
Rounding is to the nearest number.
@item 2
Rounding is towards positive infinity.
@item 3
Rounding is towards negative infinity.
@end table
@noindent
Any other value represents a machine-dependent nonstandard rounding
mode.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int FLT_RADIX
This is the value of the base, or radix, of exponent representation.
This is guaranteed to be a constant expression, unlike the other macros
described in this section.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int FLT_MANT_DIG
This is the number of base-@code{FLT_RADIX} digits in the floating-point
mantissa for the @code{float} data type.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int DBL_MANT_DIG
This is the number of base-@code{FLT_RADIX} digits in the floating-point
mantissa for the @code{double} data type.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int LDBL_MANT_DIG
This is the number of base-@code{FLT_RADIX} digits in the floating-point
mantissa for the @code{long double} data type.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int FLT_DIG
This is the number of decimal digits of precision for the @code{float}
data type. Technically, if @var{p} and @var{b} are the precision and
base (respectively) for the representation, then the decimal precision
@var{q} is the maximum number of decimal digits such that any floating
point number with @var{q} base 10 digits can be rounded to a floating
point number with @var{p} base @var{b} digits and back again, without
change to the @var{q} decimal digits.
The value of this macro is guaranteed to be at least @code{6}.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int DBL_DIG
This is similar to @code{FLT_DIG}, but is for the @code{double} data
type. The value of this macro is guaranteed to be at least @code{10}.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int LDBL_DIG
This is similar to @code{FLT_DIG}, but is for the @code{long double}
data type. The value of this macro is guaranteed to be at least
@code{10}.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int FLT_MIN_EXP
This is the minimum negative integer such that the mathematical value
@code{FLT_RADIX} raised to this power minus 1 can be represented as a
normalized floating-point number of type @code{float}. In terms of the
actual implementation, this is just the smallest value that can be
represented in the exponent field of the number.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int DBL_MIN_EXP
This is similar to @code{FLT_MIN_EXP}, but is for the @code{double} data
type.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int LDBL_MIN_EXP
This is similar to @code{FLT_MIN_EXP}, but is for the @code{long double}
data type.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int FLT_MIN_10_EXP
This is the minimum negative integer such that the mathematical value
@code{10} raised to this power minus 1 can be represented as a
normalized floating-point number of type @code{float}. This is
guaranteed to be no greater than @code{-37}.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int DBL_MIN_10_EXP
This is similar to @code{FLT_MIN_10_EXP}, but is for the @code{double}
data type.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int LDBL_MIN_10_EXP
This is similar to @code{FLT_MIN_10_EXP}, but is for the @code{long
double} data type.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int FLT_MAX_EXP
This is the maximum negative integer such that the mathematical value
@code{FLT_RADIX} raised to this power minus 1 can be represented as a
floating-point number of type @code{float}. In terms of the actual
implementation, this is just the largest value that can be represented
in the exponent field of the number.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int DBL_MAX_EXP
This is similar to @code{FLT_MAX_EXP}, but is for the @code{double} data
type.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int LDBL_MAX_EXP
This is similar to @code{FLT_MAX_EXP}, but is for the @code{long double}
data type.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int FLT_MAX_10_EXP
This is the maximum negative integer such that the mathematical value
@code{10} raised to this power minus 1 can be represented as a
normalized floating-point number of type @code{float}. This is
guaranteed to be at least @code{37}.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int DBL_MAX_10_EXP
This is similar to @code{FLT_MAX_10_EXP}, but is for the @code{double}
data type.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro int LDBL_MAX_10_EXP
This is similar to @code{FLT_MAX_10_EXP}, but is for the @code{long
double} data type.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro double FLT_MAX
The value of this macro is the maximum representable floating-point
number of type @code{float}, and is guaranteed to be at least
@code{1E+37}.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro double DBL_MAX
The value of this macro is the maximum representable floating-point
number of type @code{double}, and is guaranteed to be at least
@code{1E+37}.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro {long double} LDBL_MAX
The value of this macro is the maximum representable floating-point
number of type @code{long double}, and is guaranteed to be at least
@code{1E+37}.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro double FLT_MIN
The value of this macro is the minimum normalized positive
floating-point number that is representable by type @code{float}, and is
guaranteed to be no more than @code{1E-37}.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro double DBL_MIN
The value of this macro is the minimum normalized positive
floating-point number that is representable by type @code{double}, and
is guaranteed to be no more than @code{1E-37}.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro {long double} LDBL_MIN
The value of this macro is the minimum normalized positive
floating-point number that is representable by type @code{long double},
and is guaranteed to be no more than @code{1E-37}.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro double FLT_EPSILON
This is the minimum positive floating-point number of type @code{float}
such that @code{1.0 + FLT_EPSILON != 1.0} is true. It's guaranteed to
be no greater than @code{1E-5}.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro double DBL_EPSILON
This is similar to @code{FLT_EPSILON}, but is for the @code{double}
type. The maximum value is @code{1E-9}.
@end deftypevr
@comment float.h
@comment ISO
@deftypevr Macro {long double} LDBL_EPSILON
This is similar to @code{FLT_EPSILON}, but is for the @code{long double}
type. The maximum value is @code{1E-9}.
@end deftypevr
@node IEEE Floating Point, , Floating-Point Parameters, Floating-Point Limits
@subsection IEEE Floating Point
@cindex IEEE floating-point representation
@cindex floating-point, IEEE
@cindex IEEE Std 754
Here is an example showing how these parameters work for a common
floating point representation, specified by the @cite{IEEE Standard for
Binary Floating-Point Arithmetic (ANSI/IEEE Std 754-1985 or ANSI/IEEE
Std 854-1987)}. Nearly all computers today use this format.
The IEEE single-precision float representation uses a base of 2. There
is a sign bit, a mantissa with 23 bits plus one hidden bit (so the total
precision is 24 base-2 digits), and an 8-bit exponent that can represent
values in the range -125 to 128, inclusive.
So, for an implementation that uses this representation for the
@code{float} data type, appropriate values for the corresponding
parameters are:
@example
FLT_RADIX 2
FLT_MANT_DIG 24
FLT_DIG 6
FLT_MIN_EXP -125
FLT_MIN_10_EXP -37
FLT_MAX_EXP 128
FLT_MAX_10_EXP +38
FLT_MIN 1.17549435E-38F
FLT_MAX 3.40282347E+38F
FLT_EPSILON 1.19209290E-07F
@end example
Here are the values for the @code{double} data type:
@example
DBL_MANT_DIG 53
DBL_DIG 15
DBL_MIN_EXP -1021
DBL_MIN_10_EXP -307
DBL_MAX_EXP 1024
DBL_MAX_10_EXP 308
DBL_MAX 1.7976931348623157E+308
DBL_MIN 2.2250738585072014E-308
DBL_EPSILON 2.2204460492503131E-016
@end example

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@node Variable Argument Facilities, Memory Allocation, Common Definitions, Top
@chapter Variable Argument Facilities
@cindex variadic argument functions
@cindex variadic functions
@cindex variable number of arguments
@cindex optional arguments
@w{ISO C} defines a syntax as part of the kernel language for specifying
functions that take a variable number or type of arguments. (Such
functions are also referred to as @dfn{variadic functions}.) However,
the kernel language provides no mechanism for actually accessing
non-required arguments; instead, you use the variable arguments macros
defined in @file{stdarg.h}.
@pindex stdarg.h
@menu
* Why Variable Arguments are Used:: Using variable arguments can
save you time and effort.
* How Variable Arguments are Used:: An overview of the facilities for
receiving variable arguments.
* Variable Arguments Interface:: Detailed specification of the
library facilities.
* Example of Variable Arguments:: A complete example.
@end menu
@node Why Variable Arguments are Used, How Variable Arguments are Used, , Variable Argument Facilities
@section Why Variable Arguments are Used
Most C functions take a fixed number of arguments. When you define a
function, you also supply a specific data type for each argument.
Every call to the function should supply the same number and type of
arguments as specified in the function definition.
On the other hand, sometimes a function performs an operation that can
meaningfully accept an unlimited number of arguments.
For example, consider a function that joins its arguments into a linked
list. It makes sense to connect any number of arguments together into a
list of arbitrary length. Without facilities for variable arguments,
you would have to define a separate function for each possible number of
arguments you might want to link together. This is an example of a
situation where some kind of mapping or iteration is performed over an
arbitrary number of arguments of the same type.
Another kind of application where variable arguments can be useful is
for functions where values for some arguments can simply be omitted in
some calls, either because they are not used at all or because the
function can determine appropriate defaults for them if they're missing.
The library function @code{printf} (@pxref{Formatted Output}) is an
example of still another class of function where variable arguments are
useful. This function prints its arguments (which can vary in type as
well as number) under the control of a format template string.
@node How Variable Arguments are Used, Variable Arguments Interface, Why Variable Arguments are Used, Variable Argument Facilities
@section How Variable Arguments are Used
This section describes how you can define and call functions that take
variable arguments, and how to access the values of the non-required
arguments.
@menu
* Syntax for Variable Arguments:: How to make a prototype for a
function with variable arguments.
* Receiving the Argument Values:: Steps you must follow to access the
optional argument values.
* How Many Arguments:: How to decide whether there are more
arguments.
* Calling Variadic Functions:: Things you need to know about calling
variable arguments functions.
@end menu
@node Syntax for Variable Arguments, Receiving the Argument Values, , How Variable Arguments are Used
@subsection Syntax for Variable Arguments
A function that accepts a variable number of arguments must have at
least one required argument with a specified type. In the function
definition or prototype declaration, you indicate the fact that a
function can accept additional arguments of unspecified type by putting
@samp{@dots{}} at the end of the arguments. For example,
@example
int
func (const char *a, int b, @dots{})
@{
@dots{}
@}
@end example
@noindent
outlines a definition of a function @code{func} which returns an
@code{int} and takes at least two arguments, the first two being a
@code{const char *} and an @code{int}.@refill
An obscure restriction placed by the @w{ISO C} standard is that the last
required argument must not be declared @code{register} in the function
definition. Furthermore, this argument must not be of a function or
array type, and may not be, for example, a @code{char} or @code{short
int} (whether signed or not) or a @code{float}.
@strong{Compatibility Note:} Many older C dialects provide a similar,
but incompatible, mechanism for defining functions with variable numbers
of arguments. In particular, the @samp{@dots{}} syntax is a new feature
of @w{ISO C}.
@node Receiving the Argument Values, How Many Arguments, Syntax for Variable Arguments, How Variable Arguments are Used
@subsection Receiving the Argument Values
Inside the definition of a variadic function, to access the optional
arguments with the following three step process:
@enumerate
@item
You initialize an argument pointer variable of type @code{va_list} using
@code{va_start}.
@item
You access the optional arguments by successive calls to @code{va_arg}.
@item
You call @code{va_end} to indicate that you are finished accessing the
arguments.
@end enumerate
Steps 1 and 3 must be performed in the function that is defined to
accept variable arguments. However, you can pass the @code{va_list}
variable as an argument to another function and perform all or part of
step 2 there. After doing this, the value of the @code{va_list}
variable in the calling function becomes undefined for further calls to
@code{va_arg}; you should just pass it to @code{va_end}.
You can perform the entire sequence of the three steps multiple times
within a single function invocation. And, if the function doesn't want
to look at its optional arguments at all, it doesn't have to do any of
these steps. It is also perfectly all right for a function to access
fewer arguments than were supplied in the call, but you will get garbage
values if you try to access too many arguments.
@node How Many Arguments, Calling Variadic Functions, Receiving the Argument Values, How Variable Arguments are Used
@subsection How Many Arguments Were Supplied
There is no general way for a function to determine the number and type
of the actual values that were passed as optional arguments. Typically,
the value of one of the required arguments is used to tell the function
this information. It is up to you to define an appropriate calling
convention for each function, and write all calls accordingly.
One calling convention is to make one of the required arguments be an
explicit argument count. This convention is usable if all of the
optional arguments are of the same type.
A required argument can be used as a pattern to specify both the number
and types of the optional arguments. The format template string
argument to @code{printf} is one example of this.
A similar technique that is sometimes used is to have one of the
required arguments be a bit mask, with a bit for each possible optional
argument that might be supplied. The bits are tested in a predefined
sequence; if the bit is set, the value of the next argument is
retrieved, and otherwise a default value is used.
Another technique that is sometimes used is to pass an ``end marker''
value as the last optional argument. For example, for a function that
manipulates an arbitrary number of pointer arguments, a null pointer
might indicate the end of the argument list, provided that a null
pointer isn't otherwise meaningful to the function.
@node Calling Variadic Functions, , How Many Arguments, How Variable Arguments are Used
@subsection Calling Variadic Functions
Functions that are @emph{defined} to be variadic must also be
@emph{declared} to be variadic using a function prototype in the scope
of all calls to it. This is because C compilers might use a different
internal function call protocol for variadic functions than for
functions that take a fixed number and type of arguments. If the
compiler can't determine in advance that the function being called is
variadic, it may end up trying to call it incorrectly and your program
won't work.
@cindex function prototypes
@cindex prototypes for variadic functions
@cindex variadic functions need prototypes
Since the prototype doesn't specify types for optional arguments, in a
call to a variadic function the @dfn{default argument promotions} are
performed on the optional argument values. This means the objects of
type @code{char} or @code{short int} (whether signed or not) are
promoted to either @code{int} or @code{unsigned int}, as appropriate;
and that objects of type @code{float} are promoted to type
@code{double}. So, if the caller passes a @code{char} as an optional
argument, it is promoted to a @code{int}, and the function should get it
with @code{va_arg (@var{ap}, int)}.
Promotions of the required arguments are determined by the function
prototype in the usual way (as if by assignment to the types of the
corresponding formal parameters).
@cindex default argument promotions
@cindex argument promotion
@node Variable Arguments Interface, Example of Variable Arguments, How Variable Arguments are Used, Variable Argument Facilities
@section Variable Arguments Interface
Here are descriptions of the macros used to retrieve variable arguments.
These macros are defined in the header file @file{stdarg.h}.
@pindex stdarg.h
@comment stdarg.h
@comment ISO
@deftp {Data Type} va_list
The type @code{va_list} is used for argument pointer variables.
@end deftp
@comment stdarg.h
@comment ISO
@deftypefn {Macro} void va_start (va_list @var{ap}, @var{last_required})
This macro initialized the argument pointer variable @var{ap} to point
to the first of the optional arguments of the current function;
@var{last_required} must be the last required argument to the function.
@end deftypefn
@comment stdarg.h
@comment ISO
@deftypefn {Macro} @var{type} va_arg (va_list @var{ap}, @var{type})
The @code{va_arg} macro returns the value of the next optional argument,
and changes the internal state of @var{ap} to move past this argument.
Thus, successive uses of @code{va_arg} return successive optional
arguments.
The type of the value returned by @code{va_arg} is the @var{type}
specified in the call.
The @var{type} must match the type of the actual argument, and must not
be @code{char} or @code{short int} or @code{float}. (Remember that the
default argument promotions apply to optional arguments.)
@end deftypefn
@comment stdarg.h
@comment ISO
@deftypefn {Macro} void va_end (va_list @var{ap})
This ends the use of @var{ap}. After a @code{va_end} call, further
@code{va_arg} calls with the same @var{ap} may not work. You should invoke
@code{va_end} before returning from the function in which @code{va_start}
was invoked with the same @var{ap} argument.
In the GNU C library, @code{va_end} does nothing, and you need not ever
use it except for reasons of portability.
@refill
@end deftypefn
@node Example of Variable Arguments, , Variable Arguments Interface, Variable Argument Facilities
@section Example of Variable Arguments
Here is a complete sample function that accepts variable numbers of
arguments. The first argument to the function is the count of remaining
arguments, which are added up and the result returned. (This is
obviously a rather pointless function, but it serves to illustrate the
way the variable arguments facility is commonly used.)
@comment Yes, this example has been tested.
@example
#include <stdarg.h>
int
add_em_up (int count, @dots{})
@{
va_list ap;
int i, sum;
va_start (ap, count); /* @r{Initialize the argument list.} */
sum = 0;
for (i = 0; i < count; i++)
sum = sum + va_arg (ap, int); /* @r{Get the next argument value.} */
va_end (ap); /* @r{Clean up.} */
return sum;
@}
void main (void)
@{
/* @r{This call prints 16.} */
printf ("%d\n", add_em_up (3, 5, 5, 6));
/* @r{This call prints 55.} */
printf ("%d\n", add_em_up (10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
@}
@end example

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@ -1,81 +0,0 @@
@node Common Definitions, Memory Allocation, Error Reporting, Top
@chapter Common Definitions
There are some miscellaneous data types and macros that are not part of
the C language kernel but are nonetheless almost universally used, such
as the macro @code{NULL}. In order to use these type and macro
definitions, your program should include the header file
@file{stddef.h}.
@pindex stddef.h
@comment stddef.h
@comment ISO
@deftp {Data Type} ptrdiff_t
This is the signed integer type of the result of subtracting two
pointers. For example, with the declaration @code{char *p1, *p2;}, the
expression @code{p2 - p1} is of type @code{ptrdiff_t}. This will
probably be one of the standard signed integer types (@code{short int},
@code{int} or @code{long int}), but might be a nonstandard type that
exists only for this purpose.
@end deftp
@comment stddef.h
@comment ISO
@deftp {Data Type} size_t
This is an unsigned integer type used to represent the sizes of objects.
The result of the @code{sizeof} operator is of this type, and functions
such as @code{malloc} (@pxref{Unconstrained Allocation}) and
@code{memcpy} (@pxref{Copying and Concatenation}) that manipulate
objects of arbitrary sizes accept arguments of this type to specify
object sizes.
@end deftp
In the GNU system @code{size_t} is equivalent to one of the types
@code{unsigned int} and @code{unsigned long int}. These types have
identical properties on the GNU system, and for most purposes, you
can use them interchangeably. However, they are distinct types,
and in certain contexts, you may not treat them as identical. For
example, when you specify the type of a function argument in a
function prototype, it makes a difference which one you use. If
the system header files declare @code{malloc} with an argument
of type @code{size_t} and you declare @code{malloc} with an argument
of type @code{unsigned int}, you will get a compilation error if
@code{size_t} happens to be @code{unsigned long int} on your system.
To avoid any possibility of error, when a function argument is
supposed to have type @code{size_t}, always write the type as
@code{size_t}, and make no assumptions about what that type might
actually be.
@strong{Compatibility Note:} Types such as @code{size_t} are new
features of @w{ISO C}. Older, pre-ANSI C implementations have
traditionally used @code{unsigned int} for representing object sizes
and @code{int} for pointer subtraction results.
@comment stddef.h
@comment ISO
@deftypevr Macro {void *} NULL
@cindex null pointer
This is a null pointer constant. It can be assigned to any pointer
variable since it has type @code{void *}, and is guaranteed not to
point to any real object. This macro is the best way to get a null
pointer value. You can also use @code{0} or @code{(void *)0} as a null
pointer constant, but using @code{NULL} makes the purpose of the
constant more evident.
When passing a null pointer as an argument to a function for which there
is no prototype declaration in scope, you should explicitly cast
@code{NULL} or @code{0} into a pointer of the appropriate type. Again,
this is because the default argument promotions may not do the right
thing.
@end deftypevr
@comment stddef.h
@comment ISO
@deftypefn {Macro} size_t offsetof (@var{type}, @var{member})
This expands to a integer constant expression that is the offset of the
structure member named @var{member} in a @code{struct} of type
@var{type}. For example, @code{offsetof (struct s, elem)} is the
offset, in bytes, of the member @code{elem} in a @code{struct s}. This
macro won't work if @var{member} is a bit field; you get an error from
the C compiler in that case.
@end deftypefn

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@ -66,10 +66,10 @@ stamp-summary: summary.awk $(chapters) $(chapters-incl)
# Generate a file which can be added to the `dir' content to provide direct
# access to the documentation of the function, variables, and other
# definitions.
dir-add.texi: manual/xtract-typefun.awk $(chapters-incl)
if test -n "$(chapters-incl)"; then \
(for i in $(chapters-incl); do \
$(GAWK) -f $< < $i; \
dir-add.texi: xtract-typefun.awk $(chapters)
if test -n "$(chapters)"; then \
(for i in $(chapters); do \
$(GAWK) -f $< < $$i; \
done) | sort > $@.new; \
./move-if-change $@.new $@; \
fi

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@ -411,7 +411,36 @@ type @code{long int} rather than @code{int}.)
@deftypefun ldiv_t ldiv (long int @var{numerator}, long int @var{denominator})
The @code{ldiv} function is similar to @code{div}, except that the
arguments are of type @code{long int} and the result is returned as a
structure of type @code{ldiv}.
structure of type @code{ldiv_t}.
@end deftypefun
@comment stdlib.h
@comment GNU
@deftp {Data Type} lldiv_t
This is a structure type used to hold the result returned by the @code{lldiv}
function. It has the following members:
@table @code
@item long long int quot
The quotient from the division.
@item long long int rem
The remainder from the division.
@end table
(This is identical to @code{div_t} except that the components are of
type @code{long long int} rather than @code{int}.)
@end deftp
@comment stdlib.h
@comment GNU
@deftypefun lldiv_t lldiv (long long int @var{numerator}, long long int @var{denominator})
The @code{lldiv} function is like the @code{div} function, but the
arguments are of type @code{long long int} and the result is returned as
a structure of type @code{lldiv_t}.
The @code{lldiv} function is a GNU extension but it will eventually be
part of the next ISO C standard.
@end deftypefun
@ -519,42 +548,48 @@ to @code{EINVAL} and returns @code{0ul}.
@end deftypefun
@comment stdlib.h
@comment BSD
@deftypefun {long long int} strtoq (const char *@var{string}, char **@var{tailptr}, int @var{base})
The @code{strtoq} (``string-to-quad-word'') function is like
@code{strtol} except that is deals with extra long numbers and it
returns its value with type @code{long long int}.
@comment GNU
@deftypefun {long long int} strtoll (const char *@var{string}, char **@var{tailptr}, int @var{base})
The @code{strtoll} function is like @code{strtol} except that is deals
with extra long numbers and it returns its value with type @code{long
long int}.
If the string has valid syntax for an integer but the value is not
representable because of overflow, @code{strtoq} returns either
representable because of overflow, @code{strtoll} returns either
@code{LONG_LONG_MAX} or @code{LONG_LONG_MIN} (@pxref{Range of Type}), as
appropriate for the sign of the value. It also sets @code{errno} to
@code{ERANGE} to indicate there was overflow.
@end deftypefun
@comment stdlib.h
@comment GNU
@deftypefun {long long int} strtoll (const char *@var{string}, char **@var{tailptr}, int @var{base})
@code{strtoll} is only an commonly used other name for the @code{strtoq}
function. Everything said for @code{strtoq} applies to @code{strtoll}
as well.
The @code{strtoll} function is a GNU extension but it will eventually be
part of the next ISO C standard.
@end deftypefun
@comment stdlib.h
@comment BSD
@deftypefun {unsigned long long int} strtouq (const char *@var{string}, char **@var{tailptr}, int @var{base})
The @code{strtouq} (``string-to-unsigned-quad-word'') function is like
@code{strtoul} except that is deals with extra long numbers and it
returns its value with type @code{unsigned long long int}. The value
returned in case of overflow is @code{ULONG_LONG_MAX} (@pxref{Range of Type}).
@deftypefun {long long int} strtoq (const char *@var{string}, char **@var{tailptr}, int @var{base})
@code{strtoq} (``string-to-quad-word'') is only an commonly used other
name for the @code{strtoll} function. Everything said for
@code{strtoll} applies to @code{strtoq} as well.
@end deftypefun
@comment stdlib.h
@comment GNU
@deftypefun {unsigned long long int} strtoull (const char *@var{string}, char **@var{tailptr}, int @var{base})
@code{strtoull} is only an commonly used other name for the @code{strtouq}
function. Everything said for @code{strtouq} applies to @code{strtoull}
as well.
The @code{strtoull} function is like @code{strtoul} except that is deals
with extra long numbers and it returns its value with type
@code{unsigned long long int}. The value returned in case of overflow
is @code{ULONG_LONG_MAX} (@pxref{Range of Type}).
The @code{strtoull} function is a GNU extension but it will eventually be
part of the next ISO C standard.
@end deftypefun
@comment stdlib.h
@comment BSD
@deftypefun {unsigned long long int} strtouq (const char *@var{string}, char **@var{tailptr}, int @var{base})
@code{strtouq} (``string-to-unsigned-quad-word'') is only an commonly
used other name for the @code{strtoull} function. Everything said for
@code{strtoull} applies to @code{strtouq} as well.
@end deftypefun
@comment stdlib.h
@ -574,6 +609,16 @@ value rather than @code{long int}. The @code{atoi} function is also
considered obsolete; use @code{strtol} instead.
@end deftypefun
@comment stdlib.h
@comment GNU
@deftypefun {long long int} atoll (const char *@var{string})
This function is similar to @code{atol}, except it returns a @code{long
long int} value rather than @code{long int}.
The @code{atoll} function is a GNU extension but it will eventually be
part of the next ISO C standard.
@end deftypefun
The POSIX locales contain some information about how to format numbers
(@pxref{General Numeric}). This mainly deals with representing numbers
for better readability for humans. The functions present so far in this
@ -688,6 +733,24 @@ the sign of the value. Similarly, if the value is not representable
because of underflow, @code{strtod} returns zero. It also sets @code{errno}
to @code{ERANGE} if there was overflow or underflow.
There are two more special inputs which are recognized by @code{strtod}.
The string @code{"inf"} or @code{"infinity"} (without consideration of
case and optionally preceded by a @code{"+"} or @code{"-"} sign) is
changed to the floating-point value for infinity if the floating-point
format supports this; and to the largest representable value otherwise.
If the input string is @code{"nan"} or
@code{"nan(@var{n-char-sequence})"} the return value of @code{strtod} is
the representation of the NaN (not a number) value (if the
flaoting-point formats supports this. The form with the
@var{n-char-sequence} enables in an implementation specific way to
specify the form of the NaN value. When using the @w{IEEE 754}
floating-point format, the NaN value can have a lot of forms since only
at least one bit in the mantissa must be set. In the GNU C library
implementation of @code{strtod} the @var{n-char-sequence} is interpreted
as a number (as recognized by @code{strtol}, @pxref{Parsing of Integers})
The mantissa of the return value corresponds to this given number.
Since the value zero which is returned in the error case is also a valid
result the user should set the global variable @code{errno} to zero
before calling this function. So one can test for failures after the
@ -707,7 +770,7 @@ precision can require additional computation.
If the string has valid syntax for a floating-point number but the value
is not representable because of overflow, @code{strtof} returns either
positive or negative @code{HUGE_VALf} (@pxref{Mathematics}), depending on
positive or negative @code{HUGE_VALF} (@pxref{Mathematics}), depending on
the sign of the value.
This function is a GNU extension.
@ -725,7 +788,7 @@ of precision are required.
If the string has valid syntax for a floating-point number but the value
is not representable because of overflow, @code{strtold} returns either
positive or negative @code{HUGE_VALl} (@pxref{Mathematics}), depending on
positive or negative @code{HUGE_VALL} (@pxref{Mathematics}), depending on
the sign of the value.
This function is a GNU extension.

38
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@ -462,6 +462,44 @@ use it except for reasons of portability.
@refill
@end deftypefn
Sometimes it is necessary to parse the list of parameters more than once
or one wants to remember a certain position in the parameter list. To
do this one will have to make a copy of the current value of the
argument. But @code{va_list} is an opaque type and it is not guaranteed
that one can simply assign the value of a variable to another one of
type @code{va_list}
@comment stdarg.h
@comment GNU
@deftypefn {Macro} void __va_copy (va_list @var{dest}, va_list @var{src})
The @code{__va_copy} macro allows copying of objects of type
@code{va_list} even if this is no integral type. The argument pointer
in @var{dest} is initialized to point to the same argument as the
pointer in @var{src}.
This macro is a GNU extension but it will hopefully also be available in
the next update of the ISO C standard.
@end deftypefn
If you want to use @code{__va_copy} you should always be prepared that
this macro is not available. On architectures where a simple assignment
is invalid it hopefully is and so one should always write something like
this:
@smallexample
@{
va_list ap, save;
@dots{}
#ifdef __va_copy
__va_copy (save, ap);
#else
save = ap;
#endif
@dots{}
@}
@end smallexample
@node Variadic Example
@subsection Example of a Variadic Function

4
manual/socket.texi
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@ -826,6 +826,10 @@ string in the standard numbers-and-dots notation. The return value is
a pointer into a statically-allocated buffer. Subsequent calls will
overwrite the same buffer, so you should copy the string if you need
to save it.
In multi-threaded programs each thread has an own statically-allocated
buffer. But still subsequent calls of @code{inet_ntoa} in the same
thread will overwrite the result of the last call.
@end deftypefun
@comment arpa/inet.h

12
manual/stdio.texi
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@ -1479,11 +1479,11 @@ the @var{size} argument specifies the maximum number of characters to
produce. The trailing null character is counted towards this limit, so
you should allocate at least @var{size} characters for the string @var{s}.
The return value is the number of characters which are generated for the
given input. If this value is greater than @var{size}, not all
characters from the result have been stored in @var{s}. You should
try again with a bigger output string. Here is an example of doing
this:
The return value is the number of characters which would be generated
for the given input. If this value is greater or equal to @var{size},
not all characters from the result have been stored in @var{s}. You
should try again with a bigger output string. Here is an example of
doing this:
@smallexample
@group
@ -1503,7 +1503,7 @@ make_message (char *name, char *value)
name, value);
@end group
@group
if (nchars) >= size)
if (nchars >= size)
@{
/* @r{Reallocate buffer now that we know how much space is needed.} */
buffer = (char *) xrealloc (buffer, nchars + 1);