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malloc.3: Various minor reorganizations and wording fix-ups 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2010-10-01 20:18:07 +02:00
parent 48d8c37dd6
commit 12ec54b408
1 changed files with 50 additions and 45 deletions
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man3/malloc.3
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@ -25,24 +25,54 @@
.\" Documented MALLOC_CHECK_, Wolfram Gloger (wmglo@dent.med.uni-muenchen.de)
.\" 2007-09-15 mtk: added notes on malloc()'s use of sbrk() and mmap().
.\"
.TH MALLOC 3 2009-01-13 "GNU" "Linux Programmer's Manual"
.TH MALLOC 3 2010-10-02 "GNU" "Linux Programmer's Manual"
.SH NAME
calloc, malloc, free, realloc \- Allocate and free dynamic memory
malloc, free, calloc, realloc \- Allocate and free dynamic memory
.SH SYNOPSIS
.nf
.B #include <stdlib.h>
.sp
.BI "void *calloc(size_t " "nmemb" ", size_t " "size" );
.br
.BI "void *malloc(size_t " "size" );
.br
.BI "void free(void " "*ptr" );
.br
.BI "void *realloc(void " "*ptr" ", size_t " "size" );
.BI "void *calloc(size_t " "nmemb" ", size_t " "size" );
.fi
.SH DESCRIPTION
.PP
The
.BR malloc ()
function allocates
.I size
bytes and returns a pointer to the allocated memory.
The memory is not cleared.
If
.I size
is 0, then
.BR malloc ()
returns either NULL,
.\" glibc does this:
or a unique pointer value that can later be successfully passed to
.BR free ().
.PP
The
.BR free ()
function frees the memory space pointed to by
.IR ptr ,
which must have been returned by a previous call to
.BR malloc (),
.BR calloc ()
allocates memory for an array of
or
.BR realloc ().
Otherwise, or if
.I free(ptr)
has already been called before, undefined behavior occurs.
If
.I ptr
is NULL, no operation is performed.
.PP
The
.BR calloc ()
function allocates memory for an array of
.I nmemb
elements of
.I size
@ -59,42 +89,15 @@ returns either NULL,
or a unique pointer value that can later be successfully passed to
.BR free ().
.PP
.BR malloc ()
allocates
.I size
bytes and returns a pointer to the allocated memory.
The memory is not cleared.
If
.I size
is 0, then
.BR malloc ()
returns either NULL,
.\" glibc does this:
or a unique pointer value that can later be successfully passed to
.BR free ().
.PP
.BR free ()
frees the memory space pointed to by
.IR ptr ,
which must have been returned by a previous call to
.BR malloc (),
.BR calloc ()
or
.BR realloc ().
Otherwise, or if
.I free(ptr)
has already been called before, undefined behavior occurs.
If
.I ptr
is NULL, no operation is performed.
.PP
The
.BR realloc ()
changes the size of the memory block pointed to by
function changes the size of the memory block pointed to by
.I ptr
to
.I size
bytes.
The contents will be unchanged to the minimum of the old and new sizes;
The contents will be unchanged n the range from the start of the region
up to the minimum of the old and new sizes;
newly allocated memory will be uninitialized.
If
.I ptr
@ -120,12 +123,12 @@ If the area pointed to was moved, a
.I free(ptr)
is done.
.SH "RETURN VALUE"
For
.BR calloc ()
The
.BR malloc ()
and
.BR malloc (),
return a pointer to the allocated memory, which is suitably
aligned for any kind of variable.
.BR calloc ()
functions return a pointer to the allocated memory
that is suitably aligned for any kind of variable.
On error, these functions return NULL.
NULL may also be returned by a successful call to
.BR malloc ()
@ -140,11 +143,13 @@ or
.I size
equal to zero.
.PP
The
.BR free ()
returns no value.
function returns no value.
.PP
The
.BR realloc ()
returns a pointer to the newly allocated memory, which is suitably
function returns a pointer to the newly allocated memory, which is suitably
aligned for any kind of variable and may be different from
.IR ptr ,
or NULL if the request fails.