isupper_l(3)

isupper_l3

Upper-case character test

Part of isupper(3).

Usage

#include <ctype.h>

int

isupper(int c);

int

isupper_l(int c, locale_t loc);

Library

Standard C Library (libc, -lc)

Overview

The isupper() and isupper_l() functions test for any upper-case letter. The value of the argument must be representable as an unsigned char or the value of EOF.

In the ASCII character set, this includes the following characters (with their numeric values shown in octal):

101 ``A''102 ``B''103 ``C''104 ``D''105 ``E''
106 ``F''107 ``G''110 ``H''111 ``I''112 ``J''
113 ``K''114 ``L''115 ``M''116 ``N''117 ``O''
120 ``P''121 ``Q''122 ``R''123 ``S''124 ``T''
125 ``U''126 ``V''127 ``W''130 ``X''131 ``Y''
132 ``Z''

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

Return values

The isupper() and isupper_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 iswupper() or iswupper_l() function should be used instead.

Releases

13 releases since FreeBSD 13.2-RELEASE; the text changed 2 times.

  1. 13.2
  2. 13.3–14.5
  3. 15.0–16.0

Standards

The isupper() function conforms to ISO/IEC 9899:1990 (“ISO C90”).

History

The isupper() function first appeared in Version 7 AT&T UNIX.

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