Control Flow in Python

Understand how to control the flow of your Python programs using conditional statements, loops, and functions.

By Kevin McAleer,    2 Minutes

Introduction

In this lesson, we’ll explore how to control the flow of your Python programs using conditional statements (if, elif, else), loops (for, while), and functions.

Learning Objectives

• Understand and use conditional statements: if, elif, else.
• Understand and use loops: for, while.
• Understand how to define and call functions.

Conditional Statements

In Python, we use if, elif (else if), and else to control conditional flows. They help the program to make decisions based on certain conditions.

age = 20

if age < 13:
    print("You are a kid.")
elif age < 20:
    print("You are a teenager.")
else:
    print("You are an adult.")

Loops

Python has two types of loops - for and while.

• The for loop is used for iterating over a sequence or performing an action a specific number of times:

for i in range(5):
    print(i)

• The while loop repeats a block of code as long as a certain condition is true:

counter = 0
while counter < 5:
    print(counter)
    counter += 1

Functions

Functions are reusable pieces of code. They only run when called and can receive parameters and return data.

# Defining a function
def greet(name):
    return f"Hello, {name}!"

# Calling a function
message = greet("Alice")
print(message)  # Prints "Hello, Alice!"

Summary

In this lesson, you’ve learned about controlling the flow of your Python programs using conditional statements, loops, and functions. Understanding control flow is crucial in writing dynamic and flexible Python programs.