wcslen, wcsnlen_s

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< c ‎ | string ‎ | wide
C
Strings library
Null-terminated wide strings
Functions
Character manipulation
Conversions to numeric formats
(C95) (C99)
(C95) (C99)
String manipulation
wcslen wcsnlen_s
(C95) (C11)
(C95) (C11)
(C95) (C11)
(C95) (C11)
(C95) (C11)
(C95)
Array manipulation
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)
1) Returns the length of a wide string, that is the number of non-null wide characters that precede the terminating null wide character.
2) 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> ..

Parameters

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

Return value

1) The length of the null-terminated wide string str .
2) 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.

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.

Example

Run this code 
#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

References

  • C11 standard (ISO/IEC 9899:2011):
  • 7.29.4.6.1 The wcslen function (p: 439)
  • K.3.9.2.4.1 The wcsnlen_s function (p: 646-647)
  • C99 standard (ISO/IEC 9899:1999):
  • 7.24.4.6.1 The wcslen function (p: 385)

See also

(C11)
returns the length of a given string
(function)
C++ documentation for wcslen
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