---
name: "wcsspn"
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/wcsspn"
---

# wcsspn(3)

get length of a prefix wide-character substring

## NAME

wcsspn - get length of a prefix wide-character substring

## LIBRARY

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

## SYNOPSIS

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

**size\_t wcsspn(const wchar\_t \****wcs***, const wchar\_t \****accept***);**

## DESCRIPTION

The **wcsspn**() function is the wide-character equivalent of the [**strspn**(3)](/strspn/3.md) function. It determines the length of the longest initial segment of *wcs* which consists entirely of wide-characters listed in *accept*. In other words, it searches for the first occurrence in the wide-character string *wcs* of a wide-character not contained in the wide-character string *accept*.

## RETURN VALUE

The **wcsspn**() function returns the number of wide characters in the longest initial segment of *wcs* which consists entirely of wide-characters listed in *accept*. In other words, it returns the position of the first occurrence in the wide-character string *wcs* of a wide-character not contained in the wide-character string *accept*, or *wcslen(wcs)* if there is none.

## ATTRIBUTES

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

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

## STANDARDS

C11, POSIX.1-2008.

## HISTORY

POSIX.1-2001, C99.

## SEE ALSO

[**strspn**(3)](/strspn/3.md), [**wcscspn**(3)](/wcscspn/3.md)