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c:stdlib.h:calloc

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c:stdlib.h:calloc [2013/01/22 22:02] (current)
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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.
 +
 +
  
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c/stdlib.h/calloc.txt · Last modified: 2013/01/22 22:02 (external edit)

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