strspn(3)

strspn3

String [complementary] span

Usage

#include <string.h>

size_t strspn(const char *s, const char *accept); size_t strcspn(const char *s, const char *reject);

Library

Standard C library (libc, -lc)

Overview

strspn()

The strspn() function calculates the length (in bytes) of the initial segment of s which consists entirely of bytes in accept.

strcspn()

The strcspn() function calculates the length of the initial segment of s which consists entirely of bytes not in reject.

It is equivalent to

(strpbrk(s, reject) ?: strnul(s)) - s

Return value

The strspn() function returns the number of bytes in the initial segment of s which consist only of bytes from accept.

The strcspn() function returns the number of bytes in the initial segment of s which are not in the string reject.

Attributes

For an explanation of the terms used in this section, see attributes(7).

InterfaceAttributeValue
strspn(), strcspn()Thread safetyMT-Safe

Releases

19 releases since Debian 1.1 (Buzz); the text changed 13 times.

  1. 1.1–2.2
  2. 3.0
  3. 3.1
  4. 4.0
  5. 5.0
  6. 6.0
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11
  12. 12
  13. 13
  14. Arch

Standards

C11, POSIX.1-2008.

History

POSIX.1-2001, C89, SVr4, 4.3BSD.

From man-pages 6.19-1 in Arch Linux 2026-11-01. Parsed by carta from the page's man source.