toupper (3)

Contents

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
CONFORMING TO
BUGS
SEE ALSO
COLOPHON

NAME

toupper, tolower - convert letter to upper or lower case

SYNOPSIS

#include <ctype.h>

int toupper(int c);


int tolower(int c);

DESCRIPTION

toupper() converts the letter c to upper case, if possible.

tolower() converts the letter c to lower case, if possible.

If c is not an unsigned char value, or EOF, the behavior of these functions is undefined.

RETURN VALUE

The value returned is that of the converted letter, or c if the conversion was not possible.

CONFORMING TO

C89, C99, 4.3BSD.

BUGS

The details of what constitutes an uppercase or lowercase letter depend on the current locale. For example, the default C locale does not know about umlauts, so no conversion is done for them.

In some non-English locales, there are lowercase letters with no corresponding uppercase equivalent; the German sharp s is one example.

SEE ALSO

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

COLOPHON

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