PythonConditional Statements

Conditional Statements in Python

In any programming language, decision-making is key. Python provides conditional statements to let you run code based on conditions.

These are essential when you want your program to respond differently depending on user input, state, or data.

Types of Conditional Statements in Python

  1. if statement
  2. if-else statement
  3. if-elif-else ladder
  4. Nested if statements

Basic Syntax of if Statement

if_syntax.py
if condition:
    # block of code

Explanation:

  • The condition is an expression that evaluates to True or False.
  • If True, the indented block of code runs.
  • If False, Python skips the block.

Example 1: Simple if Statement

if_example.py
age = 18
if age >= 18:
    print("You are eligible to vote.")
output.txt
You are eligible to vote.

Example 2: if-else Statement

if_else_example.py
age = 16
if age >= 18:
    print("You are eligible to vote.")
else:
    print("You are not eligible to vote.")
output.txt
You are not eligible to vote.

Explanation:

  • The else block runs if the if condition is False.
  • This provides a clear alternative action.

Example 3: if-elif-else Ladder

if_elif_else_example.py
marks = 85
 
if marks >= 90:
    print("Grade: A")
elif marks >= 80:
    print("Grade: B")
elif marks >= 70:
    print("Grade: C")
else:
    print("Grade: F")
output.txt
Grade: B

Explanation:

  • The elif (short for else if) allows multiple conditions to be checked.
  • The first True condition will run.
  • If no condition is True, else block executes.

Example 4: Nested if Statements

nested_if_example.py
num = 10
 
if num > 0:
    if num % 2 == 0:
        print("Positive Even number")
    else:
        print("Positive Odd number")
else:
    print("Negative number")
output.txt
Positive Even number

Explanation:

  • You can nest one if block inside another for complex logic.
  • Be careful with indentation to maintain readability.

Example 5: Using Logical Operators in Conditions

logical_condition_example.py
age = 25
citizen = True
 
if age >= 18 and citizen:
    print("Eligible to vote")
else:
    print("Not eligible")
output.txt
Eligible to vote

Explanation:

  • You can combine multiple conditions using and, or, not.
  • This enables compound conditions.

Summary

  • Conditional statements are used to perform different actions based on conditions.
  • if, if-else, if-elif-else, and nested if help control the flow of your program.
  • Logical operators (and, or, not) can be used to build complex conditions.
  • Indentation is crucial in Python — it defines code blocks.

In the next section, we will explore Loops in Python — which allow you to repeat code efficiently.

Operator Precedencefor