toupper()

Prototype: int toupper(int aChar);
Header File: ctype.h (C) or cctype (C++)
Explanation: toupper accepts a character as an argument (it actually accepts an integer, but the two are interchangeable) and will convert it to uppercase, and will return the uppercase character, in the form of an ASCII integer, and leave the parameter unchanged.

Example:

//Program creates char d, sets it equal to lowercase letter
//Converts it to uppercase and outputs it
#include <cctype>
#include <iostream>

using namespace std;

int main()
{
    char d='a';  
    d=toupper(d);
    cout<<d;
}

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