4. Flow of Control

The programs we’ve written so far are straight-line programs that consist of a sequence of Python statements executed one after the other. The flow of execution is simply a straight sequence of statements, with no branching or looping back to previous statements.

In this chapter, we look at how to change the order in which statements are executed by using if-statements and loops. Both are essential in almost any nontrivial program.

Both if-statements and loops are controlled by logical expressions, and so the first part of this chapter will introduce the idea ...

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