The realloc() function returns a pointer to the newly allocated memory, which is suitably aligned for any built-in type and may be different from ptr, or NULL if the request fails. NULL may also be returned by a successful call to malloc() with a size of zero, or by a successful call to calloc() with nmemb or size equal to zero. The malloc() and calloc() functions return a pointer to the allocated memory, which is suitably aligned for any built-in type. If such an overflow occurs, reallocarray() returns NULL, sets errno to ENOMEM, and leaves the original block of memory unchanged. However, unlike that realloc() call, reallocarray() fails safely in the case where the multiplication would overflow. The reallocarray() function changes the size of the memory block pointed to by ptr to be large enough for an array of nmemb elements, each of which is size bytes. If the area pointed to was moved, a free(ptr) is done. Unless ptr is NULL, it must have been returned by an earlier call to malloc(), calloc(), or realloc().
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If ptr is NULL, then the call is equivalent to malloc(size), for all values of size if size is equal to zero, and ptr is not NULL, then the call is equivalent to free(ptr). If the new size is larger than the old size, the added memory will not be initialized. The contents will be unchanged in the range from the start of the region up to the minimum of the old and new sizes. The realloc() function changes the size of the memory block pointed to by ptr to size bytes. By contrast, an integer overflow would not be detected in the following call to malloc(), with the result that an incorrectly sized block of memory would be allocated:
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If the multiplication of nmemb and size would result in integer overflow, then calloc() returns an error. If nmemb or size is 0, then calloc() returns either NULL, or a unique pointer value that can later be successfully passed to free(). The calloc() function allocates memory for an array of nmemb elements of size bytes each and returns a pointer to the allocated memory. If ptr is NULL, no operation is performed. Otherwise, or if free(ptr) has already been called before, undefined behavior occurs. The free() function frees the memory space pointed to by ptr, which must have been returned by a previous call to malloc(), calloc(), or realloc(). If size is 0, then malloc() returns either NULL, or a unique pointer value that can later be successfully passed to free(). The malloc() function allocates size bytes and returns a pointer to the allocated memory. Void *reallocarray(void *ptr, size_t nmemb, size_t size ) įeature Test Macro Requirements for glibc (see feature_test_macros(7)): Void *calloc(size_t nmemb, size_t size )
#FMAN MALLOC FREE#
Malloc, free, calloc, realloc − allocate and free dynamic memory SYNOPSIS