C++ using islower()

~A library function, is lower(), takes a single character (a letter) as an argument and returns a nonzero integer if the letter is lowercase, or zero if it is uppercase. This function requires the file CTYPE.H. Write a program that allows the user to enter a letter, and then displays either zero or nonzero, depending on whether a lowercase or uppercase letter was entered.

 CODE:

#include <iostream>
#include <ctype.h>
/*  Author: Danial Ahmed
    Website: http://program-cpp.blogspot.com/
    Contact: danyalphc@gmail.com */
using namespace std;
int main(){
    char a;
    cout << "Enter letter: ";
    cin >> a;
    cout << islower(a) << endl;
    return 0;
}

OUTPUT:
 If lowercase

If uppercase