Break and Continue Kyewords (Importance and How to use)


Two keywords that are very important to looping are break and continue.
The break command will exit the most immediately surrounding loop regardless of what the conditions of the loop are. Break is useful if we want to exit a loop under special circumstances. For example, let's say the program we're working on is a two-person checkers game. The basic structure of the program might look like this:

while (true) 
{
    take_turn(player1);
    take_turn(player2);
}

This will make the game alternate between having player 1 and player 2 take turns. The only problem with this logic is that there's no way to exit the game; the loop will run forever! Let's try something like this instead:

while(true)
{
    if (someone_has_won() || someone_wants_to_quit() == TRUE)
    {break;}
    take_turn(player1);
    if (someone_has_won() || someone_wants_to_quit() == TRUE)
    {break;}
    take_turn(player2);
}

This code accomplishes what we want--the primary loop of the game will continue under normal circumstances, but under a special condition (winning or exiting) the flow will stop and our program will do something else.

Continue is another keyword that controls the flow of loops. If you are executing a loop and hit a continue statement, the loop will stop its current iteration, update itself (in the case of for loops) and begin to execute again from the top. Essentially, the continue statement is saying "this iteration of the loop is done, let's continue with the loop without executing whatever code comes after me." Let's say we're implementing a game of Monopoly. Like above, we want to use a loop to control whose turn it is, but controlling turns is a bit more complicated in Monopoly than in checkers. The basic structure of our code might then look something like this:

for (player = 1; someone_has_won == FALSE; player++)
    {
        if (player > total_number_of_players)
        {player = 1;}
        if (is_bankrupt(player))
        {continue;}
        take_turn(player);
    }


This way, if one player can't take her turn, the game doesn't stop for everybody; we just skip her and keep going with the next player's turn.

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