convert uppercase to lowercase

#include <iostream>
#include <string>
using namespace std;

int main() {
    string uppercase = "HELLO";
    cout << "Uppercase: " << uppercase << endl;

    for (int i = 0; i < uppercase.length(); i++) {
        if (uppercase[i] >= 'A' && uppercase[i] <= 'Z') {
            uppercase[i] = tolower(uppercase[i]);
        } 
    }
    cout << "Lowercase: " << uppercase << endl;

    return 0;
}