Python Conditional Statements

Introduction Reading Time: 10 min

Table of Contents

Description

Conditional statements are used to execute certain blocks of code based on whether a condition is true or false. These statements allow decision-making in a program, controlling the flow based on logical conditions.
Python supports the following conditional statements:
if
if-else
if-elif-else

Prerequisites

  • Understanding of Boolean expressions (True/False)
  • Familiarity with comparison and logical operators.
  • Basic knowledge of indentation and code blocks

Examples

Here's a simple program in Python:

# Example 1: Simple if statement
x = 10
if x > 5:
    print("x is greater than 5")  # Executes because condition is True

# Example 2: if-else statement
age = 17
if age >= 18:
    print("Eligible to vote")
else:
    print("Not eligible to vote")  # Executes because age < 18

# Example 3: if-elif-else ladder
score = 85
if score >= 90:
    print("Grade: A")
elif score >= 75:
    print("Grade: B")  # Executes
elif score >= 60:
    print("Grade: C")
else:
    print("Grade: D")

# Example 4: Nested if
num = -3
if num != 0:
    if num > 0:
        print("Positive number")
    else:
        print("Negative number")  # Executes
      

Real-World Applications

User authentication: Check if credentials match.

E-commerce platforms: Apply discounts based on cart value.

Banking systems: Validate transactions and limits.

Game development: Check player lives, score, level status.

Healthcare apps: Display health alerts based on condition thresholds.

Where topic Can Be Applied

Decision-making in control flow.

Form validations in web development.

Branching logic in AI model pipelines.

IoT systems: Sensor-triggered logic.

Finance apps: Rule-based interest or fraud detection.

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Interview Questions

What is the difference between if and if-else?

Can elif be used without else?

Is if a statement or a function in Python?

What happens if you forget to indent after if?

Write a Python code to check if a number is even or odd using if-else.