free
From cppreference.com
| Defined in header
<stdlib.h>
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| void free( void* ptr );
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Deallocates the space previously allocated by malloc(), calloc() or realloc(). If ptr is null-pointer, the function does nothing.
The behavior is undefined if ptr does not match a pointer returned earlier by malloc(), calloc() or realloc(). Also, the behavior is undefined if the memory area referred to by ptr has already been deallocated, that is, free() or realloc() has already been called with ptr as the argument and no calls to malloc(), calloc() or realloc() resulted in a pointer equal to ptr afterwards.
Contents |
[edit] Parameters
| ptr | - | pointer to the memory to deallocate |
[edit] Return value
(none)
[edit] Example
Run this code
#include <stdio.h> #include <stdlib.h> int main() { /* Allocate an array with 100 integers. */ int *pa = malloc(100*sizeof(int)); if (pa == NULL) { /* check that memory allocation occurred */ printf("malloc() failed in file %s at line # %d", __FILE__,__LINE__); printf("*** PROGRAM TERMINATED ***"); exit(1); } printf("starting address of pa: %p\n", (void*)pa); /* Deallocate array pa. */ free(pa), pa = NULL; /* Allocate an array with 100 doubles. */ double *pb = malloc(100*sizeof(double)); if (pb == NULL) { /* check that memory allocation occurred */ printf("malloc() failed in file %s at line # %d", __FILE__,__LINE__); printf("*** PROGRAM TERMINATED ***"); exit(1); } /* Array pb may have the same starting address that array pa had. */ printf("starting address of pb: %p\n", (void*)pb); free(pb); return 0; }
Possible output:
starting address of A: 0x2113010 starting address of B: 0x2113010
[edit] See also
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C++ documentation for free
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