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| <h5 class="subsubsection">3.2.2.5 Allocating Cleared Space</h5> |
| |
| <p>The function <code>calloc</code> allocates memory and clears it to zero. It |
| is declared in <samp><span class="file">stdlib.h</span></samp>. |
| <a name="index-stdlib_002eh-268"></a> |
| <!-- malloc.h stdlib.h --> |
| <!-- ISO --> |
| |
| <div class="defun"> |
| — Function: void * <b>calloc</b> (<var>size_t count, size_t eltsize</var>)<var><a name="index-calloc-269"></a></var><br> |
| <blockquote><p>This function allocates a block long enough to contain a vector of |
| <var>count</var> elements, each of size <var>eltsize</var>. Its contents are |
| cleared to zero before <code>calloc</code> returns. |
| </p></blockquote></div> |
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| <p>You could define <code>calloc</code> as follows: |
| |
| <pre class="smallexample"> void * |
| calloc (size_t count, size_t eltsize) |
| { |
| size_t size = count * eltsize; |
| void *value = malloc (size); |
| if (value != 0) |
| memset (value, 0, size); |
| return value; |
| } |
| </pre> |
| <p>But in general, it is not guaranteed that <code>calloc</code> calls |
| <code>malloc</code> internally. Therefore, if an application provides its own |
| <code>malloc</code>/<code>realloc</code>/<code>free</code> outside the C library, it |
| should always define <code>calloc</code>, too. |
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