std::isupper

Checks if the given character is an uppercase character as classified by the currently installed C locale. In the default "C" locale, isupper returns a nonzero value only for the uppercase letters (ABCDEFGHIJKLMNOPQRSTUVWXYZ).

If isupper returns a nonzero value, it is guaranteed that iscntrl, isdigit, ispunct, and isspace return zero for the same character in the same C locale.

The behavior is undefined if the value of ch is not representable as unsigned char and is not equal to EOF.

Parameters

Return value

Non-zero value if the character is an uppercase letter, zero otherwise.

Example

#include <iostream>
#include <cctype>
#include <clocale>
 
int main()
{
    unsigned char c = '\xc6'; // letter Æ in ISO-8859-1
 
    std::cout << "isupper(\'\\xc6\', default C locale) returned "
               << std::boolalpha << (bool)std::isupper(c) << '\n';
 
    std::setlocale(LC_ALL, "en_GB.iso88591");
    std::cout << "isupper(\'\\xc6\', ISO-8859-1 locale) returned "
              << std::boolalpha << (bool)std::isupper(c) << '\n';
 
}

isupper('\xc6', default C locale) returned false
isupper('\xc6', ISO-8859-1 locale) returned true

See also