Manual Pages  — TOUPPER

toupper – lower case to upper case letter conversion

LIBRARY SYNOPSIS DESCRIPTION RETURN VALUES COMPATIBILITY SEE ALSO STANDARDS

Standard C Library (libc, -lc)

#include <ctype.h>

int
toupper(int c);

The toupper() function converts a lower-case letter to the corresponding upper-case letter. The argument must be representable as an unsigned char or the value of EOF.

If the argument is a lower-case letter, the toupper() function returns the corresponding upper-case letter if there is one; otherwise, the argument is returned unchanged.

The BSD 4.4 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 towupper() function should be used instead.

The toupper() function conforms to ISO/IEC 9899:1990 ("ISO C90").