08-28-2008
Allocating memory for a variable in run-time called Dynamic Memory allocation.
Suppose in certain condition, if you would like to allocate some memory based on a value of an variable then we have to go for the Dynamic Memory allocation.
Simply saying, you can allocate in compile time if you know the exact size for a variable, if not you can allocate in runtime based on a runtime value.
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1 . Thanks everyone who read the post.
2 . the programe is that :
#include <stdio.h>
#include <string.h>
void do_it(char *p)
{
p = (char *) malloc(100);
(void )strcpy(p,"1234");
}
int main(void)
{
char *p;
do_it(p);
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hello sir
since by mentioning a integer pointer and storing the integers
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LEARN ABOUT OPENDARWIN
tcl_free
Tcl_Alloc(3) Tcl Library Procedures Tcl_Alloc(3)
__________________________________________________________________________________________________________________________________________________
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.
_________________________________________________________________
DESCRIPTION
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 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, how-
ever, these macros are redefined to be special debugging versions of of these procedures. To support Tcl's memory debugging within a mod-
ule, 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)