Section 4 overview

So far your programs have worked with one value at a time. Real programs handle collections — a list of users, a row of scores, a queue of tasks.

In this section you'll learn to store many values in a single variable and process them one by one, without writing the same line over and over.

What you'll cover

• Lists — store an ordered collection of values and reach any one of them by its position
• for loops — run the same block of code once for every item in a list
• range() — generate sequences of numbers to loop a fixed number of times
• while loops — repeat code as long as a condition stays true
• Totals and counters — the accumulator pattern for adding things up and counting them

By the end of this section

You'll be able to take a list of data and total it, count it, transform it, or print it — the everyday work of almost every program you'll ever write.

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