1TOUPPER(3)                 Linux Programmer's Manual                TOUPPER(3)
2
3
4

NAME

6       toupper, tolower - convert letter to upper or lower case
7

SYNOPSIS

9       #include <ctype.h>
10
11       int toupper(int c);
12       int tolower(int c);
13

DESCRIPTION

15       toupper() converts the letter c to upper case, if possible.
16
17       tolower() converts the letter c to lower case, if possible.
18
19       If  c  is  not  an  unsigned char value, or EOF, the behaviour of these
20       functions is undefined.
21

RETURN VALUE

23       The value returned is that of the converted letter, or c if the conver‐
24       sion was not possible.
25

CONFORMING TO

27       C89, C99, 4.3BSD
28

BUGS

30       The details of what constitutes an uppercase or lowercase letter depend
31       on the current locale.  For example, the default "C"  locale  does  not
32       know about umlauts, so no conversion is done for them.
33
34       In some non-English locales, there are lowercase letters with no corre‐
35       sponding uppercase equivalent; the German sharp s is one example.
36

SEE ALSO

38       isalpha(3), setlocale(3), towlower(3), towupper(3), locale(7)
39
40
41
42GNU                               1993-04-04                        TOUPPER(3)