c:stdlib.h:calloc
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| + | {{keywords>wiki library source code example reference}} | ||
| + | ====== calloc ====== | ||
| + | <code c> | ||
| + | #include <stdlib.h> | ||
| + | void *calloc(size_t nitems, size_t size); | ||
| + | </code> | ||
| + | |||
| + | === description === | ||
| + | The calloc() function shall allocate unused space for an array of nelem elements each of whose size in bytes is elsize. \\ | ||
| + | The space shall be initialized to all bits 0.\\ | ||
| + | \\ | ||
| + | The order and contiguity of storage allocated by successive calls to calloc() is unspecified. \\ | ||
| + | The pointer returned if the allocation succeeds shall be suitably aligned so that it may be assigned to a \\ | ||
| + | pointer to any type of object and then used to access such an object or an array of such objects in the space \\ | ||
| + | allocated (until the space is explicitly freed or reallocated). Each such allocation shall yield a pointer to an object disjoint \\ | ||
| + | from any other object. The pointer returned shall point to the start (lowest byte address) of the allocated space. \\ | ||
| + | If the space cannot be allocated, a null pointer shall be returned. If the size of the space requested is 0, the behavior \\ | ||
| + | is implementation-defined: the value returned shall be either a null pointer or a unique pointer.\\ | ||
| + | |||
| + | === return value === | ||
| + | Upon successful completion with both nelem and elsize non-zero, calloc() shall return a pointer to the allocated space. \\ | ||
| + | If either nelem or elsize is 0, then either a null pointer or a unique pointer value that can be successfully passed to free() shall be returned.\\ | ||
| + | Otherwise, it shall return a null pointer and set errno to indicate the error.\\ | ||
| + | |||
| + | ===== calloc C Sourcecode Example ===== | ||
| + | <code c> | ||
| + | /* | ||
| + | * calloc example code | ||
| + | * http://code-reference.com/c/stdlib.h/calloc | ||
| + | */ | ||
| + | |||
| + | #include <stdio.h> /* including standard library */ | ||
| + | //#include <windows.h> /* uncomment this for Windows */ | ||
| + | |||
| + | #include <stdlib.h> | ||
| + | |||
| + | int main( void) | ||
| + | { | ||
| + | int newsize, *ptr; | ||
| + | |||
| + | printf("Enter the number of type int to allocate: "); | ||
| + | scanf("%d", &newsize); | ||
| + | |||
| + | ptr = calloc(newsize, sizeof(int)); | ||
| + | |||
| + | if (ptr != NULL) { | ||
| + | printf("allocation of memory was successfully.\n"); | ||
| + | } | ||
| + | else { | ||
| + | printf("allocation of memory failed.\n"); | ||
| + | } | ||
| + | |||
| + | return 0; | ||
| + | } | ||
| + | </code> | ||
| + | |||
| + | ==== Output ==== | ||
| + | |||
| + | Output allocation successfully: | ||
| + | user@host:~$ ./calloc | ||
| + | Enter the number of type int to allocate: 2345 | ||
| + | allocation of memory was successfully. | ||
| + | |||
| + | Output allocation failed: | ||
| + | user@host:~$ ./calloc | ||
| + | Enter the number of type int to allocate: 9992992992 | ||
| + | allocation of memory failed. | ||
| + | |||
| + | |||
on the occasion of the current invasion of Russia in Ukraine
c/stdlib.h/calloc.txt · Last modified: 2024/02/16 01:04 (external edit)
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