_countof Macro
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The latest version of this topic can be found at _countof Macro.
Compute the number of elements in a statically-allocated array.
Syntax
size_t _countof(
array
);
Parameters
array
The name of an array.
Return Value
The number of elements in the array, expressed as a size_t.
Remarks
Ensure that array is actually an array, not a pointer. In C, _countof will produce erroneous results if array is a pointer. In C++, _countof will fail to compile if array is a pointer.
Requirements
| Macro | Required header |
|---|---|
_countof |
<stdlib.h> |
Example
// crt_countof.cpp
#define _UNICODE
#include <stdio.h>
#include <stdlib.h>
#include <tchar.h>
int main( void )
{
_TCHAR arr[20], *p;
printf( "sizeof(arr) = %zu bytes\n", sizeof(arr) );
printf( "_countof(arr) = %zu elements\n", _countof(arr) );
// In C++, the following line would generate a compile-time error:
// printf( "%zu\n", _countof(p) ); // error C2784 (because p is a pointer)
_tcscpy_s( arr, _countof(arr), _T("a string") );
// unlike sizeof, _countof works here for both narrow- and wide-character strings
}
sizeof(arr) = 40 bytes
_countof(arr) = 20 elements