---
name: "wcsnlen"
section: "3"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/wcsnlen"
---

# wcsnlen(3)

determine the length of a fixed-size wide-character string

## NAME

wcsnlen - determine the length of a fixed-size wide-character string

## LIBRARY

Standard C library (*libc*, *-lc*)

## SYNOPSIS

```
#include <wchar.h>
```

**size\_t wcsnlen(const wchar\_t** s**\[\], size\_t** maxlen**);**

Feature Test Macro Requirements for glibc (see [**feature\_test\_macros**(7)](/feature_test_macros/7.md)):

**wcsnlen**():

```
    Since glibc 2.10:
        _POSIX_C_SOURCE >= 200809L
    Before glibc 2.10:
        _GNU_SOURCE
```

## DESCRIPTION

The **wcsnlen**() function is the wide-character equivalent of the [**strnlen**(3)](/strnlen/3.md) function. It returns the number of wide-characters in the string pointed to by *s*, not including the terminating null wide character (L'\\0'), but at most *maxlen* wide characters (note: this parameter is not a byte count). In doing this, **wcsnlen**() looks at only the first *maxlen* wide characters at *s* and never beyond *s\[maxlen-1\]*.

## RETURN VALUE

The **wcsnlen**() function returns *wcslen(s)*, if that is less than *maxlen*, or *maxlen* if there is no null wide character among the first *maxlen* wide characters pointed to by *s*.

## ATTRIBUTES

For an explanation of the terms used in this section, see [**attributes**(7)](/attributes/7.md).

| | | |
| --- | --- | --- |
| **Interface** | **Attribute** | **Value** |
| **wcsnlen**() | Thread safety | MT-Safe |

## STANDARDS

POSIX.1-2008.

## HISTORY

glibc 2.1.

## SEE ALSO

[**strnlen**(3)](/strnlen/3.md), [**wcslen**(3)](/wcslen/3.md)