// Counter examples
#include <iostream>
using namespace std;
int main()
{
    // Count up. This prints `x` number of stars.

    // Consider other combinations, like start
    // at 1 but loop as long as i <= x.

    int x = 10;
    int i = 0;   // This is my counter variable.
    while(i < x)
    {
        cout << i << '*';
        i++;
    }
    cout << endl;

    // Or here is a variation that counts down.
    // In that case, we don't need an extra
    // variable, unless you need to save the
    // value of `x` for future calculations.

    int y = 10;
    while( y > 0 )
    {
        cout << y << '*';
        y--;
    }
    cout << endl;

    return 0;
}

// Input validation loops
#include <iostream>
using namespace std;
int main()
{
    int hour;
    cout << "Enter hour (0-23): ";
    cin >> hour;
    while(hour < 0 || hour > 23) {
        cout << "Error, out of range.";
        cout << "Enter hour (0-23): "; // Unfortunate duplication
        cin >> hour;
    }

    // To get to this point, hour must be valid.
    cout << hour-12 << endl;

    // Here's an alternative, using the "empty for"
    // style of infinite loop.
    for(;;)
    {
        cout << "Enter hour (0-23): ";
        cin >> hour;
        if(hour >= 0 && hour <= 23) break;
        cout << "Error, out of range." << endl;
    }

    // To get to this point, hour must be valid.
    cout << hour-12 << endl;

    return 0;
}

// My solution to project 5, on 12- and 24-hour time
// C League, 2016-10-26
#include <iostream>
#include <iomanip>
using namespace std;
int main()
{
    int hour = 0;
    int minute = 0;
    cout << "Enter hour (0-23): ";
    cin >> hour;
    if(hour < 0  ||  hour > 23)
    {
        cout << "ERROR: invalid hour\n";
        return 0;
    }
    cout << "Enter minute (0-59): ";
    cin >> minute;
    if(minute < 0 || minute > 59)
    {
        cout << "ERROR: invalid minute\n";
        return 0;
    }
    // Print 24-hour time, with leading zeroes
    if(hour < 10) cout << '0';  // Technique #1
    cout << hour << ":";
                                // Technique #2
    cout.fill('0');             // Set fill character
    cout << setw(2) << minute << " is ";

    // Print 12-hour time
    int hour12;
    if(hour == 0) hour12 = 12;
    else if(hour < 13) hour12 = hour;
    else hour12 = hour - 12;

    cout << setw(2) << hour12 << ':'
         << setw(2) << minute << ' ';

    if(hour < 12) cout << "AM";
    else cout << "PM";
    cout << endl;

    // English approximate time
    if(minute >= 8 && minute <= 22) {
        cout << "quarter past";
    }
    else if(minute >= 23 && minute <= 37) {
        cout << "half past";
    }
    else if(minute >= 38 && minute <= 52) {
        cout << "quarter til";
        hour++;                 // increment hour
    }
    else if(minute >= 53) {
        hour++;                 // increment hour
    }

    cout << ' ';
    switch(hour)
    {
    case 0: case 24: cout << "midnight"; break;
    case 1: case 13: cout << "one"; break;
    case 2: case 14: cout << "two"; break;
    case 3: case 15: cout << "three"; break;
    case 4: case 16: cout << "four"; break;
    case 5: case 17: cout << "five"; break;
    case 6: case 18: cout << "six"; break;
    case 7: case 19: cout << "seven"; break;
    case 8: case 20: cout << "eight"; break;
    case 9: case 21: cout << "nine"; break;
    case 10: case 22: cout << "ten"; break;
    case 11: case 23: cout << "eleven"; break;
    case 12: cout << "noon"; break;
    }
    if(hour >= 1 && hour <= 11) {
        cout << " in the morning";
    }
    else if(hour > 12 && hour <= 17) {
        cout << " in the afternoon";
    }
    else if(hour >= 18 && hour <= 23) {
        cout << " in the evening";
    }
    cout << endl;

    return 0;
}