_toupper() — Translate lowercase characters to uppercase

Standards

Standards / Extensions	C or C++	Dependencies
XPG4 XPG4.2 Single UNIX Specification, Version 3	both

#define _XOPEN_SOURCE
#include <ctype.h>

int _toupper(int c);

The _toupper() macro is equivalent to toupper(c) except that the argument c must be a lowercase letter.

_toupper() returns the uppercase letter corresponding to the argument passed.