#include <iostream>
#include <string>

using namespace std;

int main() {
    //                         11
    //               012345678901
    string phrase = "Hello World!";
    int i;

    cout << "The phrase \"" << phrase << "\" is " << phrase.size() 
         << " characters long." << endl;
    cout << "The first letter is '" << phrase.front() << "'." << endl;
    cout << "The last letter is '" << phrase.back() << "'." << endl;

    cout << endl;

    i = 0;
    while ( i < phrase.size()) {
        cout << "letter " << i << "  is " << phrase[i] << "."  << endl;

        if (isblank(phrase[i])) {
            cout << "By the way, that is a blank." << endl;
        }

        if (isalpha(phrase[i])) {
            cout << "By the way, that is a letter." << endl;
        }

        i++;
    }

    cout << endl;

    i = 0;
    while ( i < phrase.size()) {
        //phrase[i] = 'x';
        phrase[i] =  toupper(phrase[i]);
        cout << "In the loop, i = " << i << endl;
        cout << "The phrase is \"" << phrase << "\"." << endl;
        cout << endl;
        i++;
    }

    cout << endl << endl;

    //                           11
    //                 012345678901
    //string phrase = "Hello World!";

    i = phrase.size()-1;
    while ( i >= 0 ) {
        cout << phrase[i];
        i--;
    }
    cout << endl;

    return 0;
}