wcslen, wcsnlen_s - cppreference.com (original) (raw)

Defined in header <wchar.h>
size_t wcslen( const wchar_t *str );	(1)	(since C95)
size_t wcsnlen_s(const wchar_t *str, size_t strsz);	(2)	(since C11)

Returns the length of a wide string, that is the number of non-null wide characters that precede the terminating null wide character.
Same as (1), except that the function returns zero if str is a null pointer and returns strsz if the null wide character was not found in the first strsz wide characters of src

As with all bounds-checked functions, wcslen_s is only guaranteed to be available if __STDC_LIB_EXT1__ is defined by the implementation and if the user defines __STDC_WANT_LIB_EXT1__ to the integer constant 1 before including <stdio.h>..

[edit] Parameters

str	-	pointer to the null-terminated wide string to be examined
strsz	-	maximum number of wide characters to examine

[edit] Return value

The length of the null-terminated wide string str.
The length of the null-terminated wide string str on success, zero if str is a null pointer, strsz if the null wide character was not found.

[edit] Notes

strnlen_s and wcsnlen_s are the only bounds-checked functions that do not invoke the runtime constraints handler. They are pure utility functions used to provide limited support for non-null terminated strings.

[edit] Example

#include <wchar.h> #include <stdio.h> int main(void) { wchar_t str[] = L"How many wide characters does this string contain?"; printf("without null character: %zu\n", wcslen(str)); printf("with null character: %zu\n", sizeof str / sizeof *str); }

Output:

without null character: 50 with null character: 51

[edit] References