'\"
'\" 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.
'\"
.TH Tcl_Alloc 3 9.0 Tcl "Tcl Library Procedures"
.so man.macros
.BS
.SH NAME
Tcl_Alloc, Tcl_Free, Tcl_Realloc, Tcl_AttemptAlloc, Tcl_AttemptRealloc, Tcl_GetMemoryInfo \- allocate or free heap memory
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
char *
\fBTcl_Alloc\fR(\fIsize\fR)
.sp
\fBTcl_Free\fR(\fIptr\fR)
.sp
void *
\fBTcl_Realloc\fR(\fIptr, size\fR)
.sp
void *
\fBTcl_AttemptAlloc\fR(\fIsize\fR)
.sp
void *
\fBTcl_AttemptRealloc\fR(\fIptr, size\fR)
.sp
\fBTcl_GetMemoryInfo\fR(\fIdsPtr\fR)
.fi
.SH ARGUMENTS
.AS char *size
.AP "size_t" size in
Size in bytes of the memory block to allocate.
.AP char *ptr in
Pointer to memory block to free or realloc.
.AP Tcl_DString *dsPtr in
Initialized DString pointer.
.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
When a module or Tcl itself is compiled with \fBTCL_MEM_DEBUG\fR defined,
the procedures \fBTcl_Alloc\fR, \fBTcl_Free\fR, \fBTcl_Realloc\fR,
\fBTcl_AttemptAlloc\fR, and \fBTcl_AttempRealloc\fR are implemented
as macros, redefined to be special debugging versions of these procedures.
.PP
\fBTcl_GetMemoryInfo\fR appends a list-of-lists of memory stats to the
provided DString. This function cannot be used in stub-enabled extensions,
and it is only available if Tcl is compiled with the threaded memory allocator
When used in stub-enabled embedders, the stubs table must be first initialized
using one of \fBTcl_InitSubsystems\fR, \fBTcl_SetPanicProc\fR,
\fBTcl_FindExecutable\fR or \fBTclZipfs_AppHook\fR.

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