1TOUPPER(3)                 Linux Programmer's Manual                TOUPPER(3)
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NAME

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

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

15       toupper() converts the letter c to upper case, if possible.
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17       tolower() converts the letter c to lower case, if possible.
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19       If c is not an unsigned char value, or EOF, the behavior of these func‐
20       tions is undefined.
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RETURN VALUE

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

27       C89, C99, 4.3BSD.
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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.
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34       In some non-English locales, there are lowercase letters with no corre‐
35       sponding uppercase equivalent; the German sharp s is one example.
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SEE ALSO

38       isalpha(3), setlocale(3), towlower(3), towupper(3), locale(7)
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COLOPHON

41       This page is part of release 3.25 of the Linux  man-pages  project.   A
42       description  of  the project, and information about reporting bugs, can
43       be found at http://www.kernel.org/doc/man-pages/.
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47GNU                               1993-04-04                        TOUPPER(3)
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