Control Flow in Python¶

Control flow determines which parts of a program execute and in what order.

So far, our programs executed sequentially — one line after another. Control flow introduces mechanisms that allow programs to:

make decisions
repeat actions
terminate loops early
select behaviors based on patterns

These constructs are essential for building real programs. The following diagram shows how these control flow mechanisms branch from sequential execution:

flowchart TD
    A[Program Start] --> B[Sequential Execution]
    B --> C[Conditional Branching]
    B --> D[Loops]
    C --> E[Pattern Matching]
    D --> F[Loop Control]

This chapter introduces Python's core control flow tools:

Construct	Purpose
`if`	conditional branching
`for`	iteration over sequences
`while`	repetition while condition holds
`break`	exit loops early
`continue`	skip an iteration
`else` on loops	detect successful loop completion
ternary expression	inline conditional expression
`match`	structural pattern matching

Understanding control flow allows programs to adapt their behavior based on data and conditions.