isrune(3)

isrune3

Valid character test

Usage

#include <ctype.h>

int

isrune(int c);

int

isrune_l(int c, locale_t loc);

Library

Standard C Library (libc, -lc)

Overview

The isrune() and isrune_l() functions test for any character that is valid in the current character set. In the ASCII character set, this is equivalent to isascii().

The isrune_l() function takes an explicit locale argument, whereas the isrune() function uses the current global or per-thread locale.

Return values

The isrune() and isrune_l() functions return zero if the character tests false and return non-zero if the character tests true.

Compatibility

The 4.4BSD extension of accepting arguments outside of the range of the unsigned char type in locales with large character sets is considered obsolete and may not be supported in future releases. The iswrune() or iswrune_l() function should be used instead.

Releases

52 releases since FreeBSD 5.3-RELEASE; the text changed 33 times.

  1. 5.3–6.3
  2. 6.4
  3. 7.0
  4. 7.1
  5. 7.2
  6. 7.3
  7. 7.4
  8. 8.0
  9. 8.1
  10. 8.2
  11. 8.3
  12. 8.4
  13. 9.0
  14. 9.1
  15. 9.2
  16. 9.3
  17. 10.0
  18. 10.1
  19. 10.2
  20. 10.3
  21. 10.4
  22. 11.0
  23. 11.1
  24. 11.2
  25. 11.3
  26. 11.4
  27. 12.0
  28. 12.1
  29. 12.2
  30. 12.3
  31. 12.4
  32. 13.0–13.1
  33. 13.2
  34. 13.3–16.0

History

The isrune() function appeared in 4.4BSD.

From base 16.0-CURRENT-20261027-61c70dc16a79 in FreeBSD 16.0-CURRENT (2026-10-27). Parsed by carta from the page's mdoc source.