Mac Programming for Absolute Beginners

Chapter 7. Repeating Code with Loops

The three basic building blocks for creating programs are the sequential ordering of code, branches (to make decisions), and loops (to run one or more instructions repetitively). Rather than write one long set of instructions to accomplish a task, a loop lets you write a shorter set of instructions that runs multiple times.

Suppose your program needs to ask for a password from the user before granting access. You could write a bunch of code that keeps checking for a valid password, but this gives you no idea ahead of time how many times someone may try to type in a valid password. With a loop, you just need to write one set of instructions for checking the validity of a password and, if it's valid, granting ...