Say It Once, Do It Many Times: Loops in Code

Imagine your teacher says: 'Clap your hands three times.' You clap, clap, clap — done! Now imagine she said 'Clap your hands' fifty times. That is a very long list! Computers face this problem too. Writing the same instruction over and over wastes space and time. Coders found a clever shortcut. Can you guess what it might be?

A loop is an instruction that tells the computer to repeat a set of steps a certain number of times — without you having to write those steps over and over again. Think of a loop like a roundabout. You go around the circle, and each time you pass the start you do the same thing again. When you have been around enough times, you exit. Here is the big idea: instead of writing 'move forward' ten times, you write 'repeat 10 times: move forward'. The computer reads that one instruction and carries out the action ten times all by itself. Loops have two important parts: 1. The REPEAT number — this tells the computer how many times to go around. 2. The BODY — this is the set of actions inside the loop that gets repeated. When the computer finishes all the repeats, it stops the loop and moves on to the next instruction. Loops save coders a huge amount of time. A loop can repeat an action a million times, and you only have to write it once!