'\"
'\" Copyright (c) 1995-1996 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" RCS: @(#) $Id: Alloc.3,v 1.10.8.1 2009/03/30 18:48:18 dgp Exp $
'\" 
.so man.macros
.TH Tcl_Alloc 3 7.5 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_Alloc, Tcl_Free, Tcl_Realloc, Tcl_AttemptAlloc, Tcl_AttemptRealloc, ckalloc, ckfree, ckrealloc, attemptckalloc, attemptckrealloc \- allocate or free heap memory
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
char *
\fBTcl_Alloc\fR(\fIsize\fR)
.sp
void
\fBTcl_Free\fR(\fIptr\fR)
.sp
char *
\fBTcl_Realloc\fR(\fIptr, size\fR)
.sp
char *
\fBTcl_AttemptAlloc\fR(\fIsize\fR)
.sp
char *
\fBTcl_AttemptRealloc\fR(\fIptr, size\fR)
.sp
char *
\fBckalloc\fR(\fIsize\fR)
.sp
void
\fBckfree\fR(\fIptr\fR)
.sp
char *
\fBckrealloc\fR(\fIptr, size\fR)
.sp
char *
\fBattemptckalloc\fR(\fIsize\fR)
.sp
char *
\fBattemptckrealloc\fR(\fIptr, size\fR)
.SH ARGUMENTS
.AS char *size
.AP "unsigned int" size in
Size in bytes of the memory block to allocate.
.AP char *ptr in
Pointer to memory block to free or realloc.
.BE

.SH DESCRIPTION
.PP
These procedures provide a platform and compiler independent interface
for memory allocation.  Programs that need to transfer ownership of
memory blocks between Tcl and other modules should use these routines
rather than the native \fBmalloc()\fR and \fBfree()\fR routines
provided by the C run-time library.
.PP
\fBTcl_Alloc\fR returns a pointer to a block of at least \fIsize\fR
bytes suitably aligned for any use.
.PP
\fBTcl_Free\fR makes the space referred to by \fIptr\fR available for
further allocation.
.PP
\fBTcl_Realloc\fR changes the size of the block pointed to by
\fIptr\fR to \fIsize\fR bytes and returns a pointer to the new block.
The contents will be unchanged up to the lesser of the new and old
sizes.  The returned location may be different from \fIptr\fR.  If
\fIptr\fR is NULL, this is equivalent to calling \fBTcl_Alloc\fR with
just the \fIsize\fR argument.
.PP
\fBTcl_AttemptAlloc\fR and \fBTcl_AttemptRealloc\fR are identical in
function to \fBTcl_Alloc\fR and \fBTcl_Realloc\fR, except that
\fBTcl_AttemptAlloc\fR and \fBTcl_AttemptRealloc\fR will not cause the Tcl
interpreter to \fBpanic\fR if the memory allocation fails.  If the
allocation fails, these functions will return NULL.  Note that on some
platforms, but not all, attempting to allocate a zero-sized block of
memory will also cause these functions to return NULL.
.PP
The procedures \fBckalloc\fR, \fBckfree\fR, \fBckrealloc\fR,
\fBattemptckalloc\fR, and \fBattemptckrealloc\fR are implemented
as macros.  Normally, they are synonyms for the corresponding
procedures documented on this page.  When Tcl and all modules
calling Tcl are compiled with \fBTCL_MEM_DEBUG\fR defined, however,
these macros are redefined to be special debugging versions
of these procedures.  To support Tcl's memory debugging within a
module, use the macros rather than direct calls to \fBTcl_Alloc\fR, etc.

.SH KEYWORDS
alloc, allocation, free, malloc, memory, realloc, TCL_MEM_DEBUG