Tcl_Alloc(3) Tcl Library Procedures Tcl_Alloc(3)
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NAME
Tcl_Alloc, Tcl_Free, Tcl_Realloc, Tcl_AttemptAlloc, Tcl_AttemptRealloc, ckalloc, ckfree, ckrealloc,
attemptckalloc, attemptckrealloc - allocate or free heap memory
SYNOPSIS
#include <tcl.h>
char *
Tcl_Alloc(size)
void
Tcl_Free(ptr)
char *
Tcl_Realloc(ptr, size)
char *
Tcl_AttemptAlloc(size)
char *
Tcl_AttemptRealloc(ptr, size)
char *
ckalloc(size)
void
ckfree(ptr)
char *
ckrealloc(ptr, size)
char *
attemptckalloc(size)
char *
attemptckrealloc(ptr, size)
ARGUMENTS
int size (in) Size in bytes of the memory block to allocate.
char *ptr (in) Pointer to memory block to free or realloc.
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DESCRIPTION
These procedures provide a platform and compiler independent interface for memory allocation. Pro-grams Programs
grams that need to transfer ownership of memory blocks between Tcl and other modules should use these
routines rather than the native malloc() and free() routines provided by the C run-time library.
Tcl_Alloc returns a pointer to a block of at least size bytes suitably aligned for any use.
Tcl_Free makes the space referred to by ptr available for further allocation.
Tcl_Realloc changes the size of the block pointed to by ptr to size 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 ptr.
Tcl_AttemptAlloc and Tcl_AttemptRealloc are identical in function to Tcl_Alloc and Tcl_Realloc,
except that Tcl_AttemptAlloc and Tcl_AttemptRealloc will not cause the Tcl interpreter to panic if
the memory allocation fails. If the allocation fails, these functions will return NULL. Note that
on some platforms, attempting to allocate a block of memory will also cause these functions to return
NULL.
The procedures ckalloc, ckfree, ckrealloc, attemptckalloc, and attemptckrealloc 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 TCL_MEM_DEBUG defined, however, these macros are
redefined to be special debugging versions of of these procedures. To support Tcl's memory debugging
within a module, use the macros rather than direct calls to Tcl_Alloc, etc.
KEYWORDS
alloc, allocation, free, malloc, memory, realloc, TCL_MEM_DEBUG
Tcl 7.5 Tcl_Alloc(3)
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