String To Upper/Lower Case And Reverse

#include <iostream>
#include <string>

#define UP_A 65
#define UP_Z 91

#define LOW_A 97
#define LOW_Z 122

int main() {

    std::string word;
    std::string upper;
    std::string lower;
    std::string backwards;

    std::cout << "Enter word: ";
    std::cin >> word;

    //Lower To Upper:
    for (int i = 0; i < word.length(); i++) {
        if (word.at(i) >= LOW_A && word.at(i) <= LOW_Z) {
            upper += (word.at(i) - 32);
        }
        else {
            upper += word.at(i);
        }
    }

    //Upper To Lower:
    for (int i = 0; i < word.length(); i++) {
        if (word.at(i) >= UP_A && word.at(i) <= UP_Z) {
            lower += (word.at(i) + 32);
        }
        else {
            lower += word.at(i);
        }
    }

    //Reverse String:
    for (int i = word.length(); i > 0; i--) {
        backwards += word.at(i - 1);
    }

    //Print Data:
    std::cout << "Upper: " << upper << "\n";
    std::cout << "Lower: " << lower << "\n";
    std::cout << "Reversed: " << backwards << "\n";

    system("PAUSE");
}