The goal for this exercise is to understand the break and continue keywords, so that you can exhibit more complex control over the loops that you create.

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There are times when you'll want to end a loop early, or skip the rest of the loop, and go to the next iteration of the loop (without ending the loop). For example, one way to write a loop that will print all even integers less than 300 (starting at 1), and that stops as soon as it finds the first odd number higher than 15, would be as follows:

while (num <= 300)
{
    // if we've found the first odd #,that's > 15
    // exit the loop
    if (num > 15 && num % 2 == 1)
        break;
    // If the number is odd, skip back to the
    // while(num <= 300) line
    if (num % 2 == 1)
        continue;

    //otherwise, print the number:
    Console.WriteLine(num);
}
Console.WriteLine("All done!");
// (Yes, there are better ways to accomplish this :) )

Note the use of the break keyword – if we want to skip the rest of this iteration of the loop, and stop running the loop altogether, we use break (such as when we've found an odd number higher than 15 – we're done).

Note the use of the continue keyword – if we want to skip the rest of this iteration of the loop, but keep running the loop, we use continue (such as when skipping the even numbers).

You may be tempted to try using a pattern like the following:

int num = 0;
while (true)
{
    num++;

    // if we've found the first odd #,that's > 15
    // I'm relying on the break keyword to exit the loop 
    if (num > 15 && num % 2 == 1)
        break;

    // If the number is odd, skip back to the
    // while(num <= 300) line
    if (num % 2 == 1)
        continue;
    //otherwise, print the number:
    Console.WriteLine(num);
}
Console.WriteLine("All done!");

using a pattern like while(true), and then relying on break statements to exit the loop should generally be avoided, since the loop normally would give us (as programmers) valuable information about what the intention of the loop is. As a matter of fact, both of the above examples would be better written as follows:

// if the number is less than 15, keep going
while (num <= 15)
{
    // If the number is odd, skip back to the
    // while(num <= 15) line
    if (num % 2 == 1)
        continue;
    //otherwise, print the even number:
    Console.WriteLine(num);
}
Console.WriteLine("All done!");

Side-Note: If you've done the exercise(s) for the switch statement, you'll notice that the switch statement also makes use of the break keyword. In that situation, the meaning is similar - break will make sure that you break out of the switch, rather than going on to the next case. However, you'll end up using switch/break together so often that it may seem like in that case, break is merely part of the syntax of a switch statement (which isn't a bad way to think about switches). As you've seen above, break can also be used in other circumstances, so it's important to keep both purposes in your head – break can break out of a switch (as part of a switch's standard syntax), and break can be used to break out of a loop (in a more general-purpose sense).