Nested-if statement in Python

For more complex decision trees, Python allows for nested if statements where one if statement is placed inside another. This article will explore the concept of nested if statements in Python, providing clarity on how to use them effectively.

Python Nested if Statement

A nested if statement in Python is an if statement located within another if or else clause. This nesting can continue with multiple layers, allowing programmers to evaluate multiple conditions sequentially. It's particularly useful in scenarios where multiple criteria need to be checked before taking an action.

Example of Nested If Statements

Let’s consider a practical example to understand how nested if statements work in Python.

age = 30
member = True
if age > 18:
    if member:
        print("Ticket price is $12.")
    else:
        print("Ticket price is $20.")
else:
    if member:
        print("Ticket price is $8.")
    else:
        print("Ticket price is $10.")

Ticket price is $12.

In this example, the outer if checks the age, while the inner if checks the membership status to determine the ticket price.

Syntax of Nested If Statements in Python

The basic syntax of a nested if statement in Python is as follows:

if condition1:

# Code to execute if condition1 is true

if condition2:

# Code to execute if both condition1 and condition2 are true

Flowchart of Nested if Statement

The flowchart illustrates the concept of a nested if statement in programming.

Here’s a summarized explanation of its structure:

1. Initial Condition Check:
   • An if statement evaluates a primary condition.
   • If true, the flow proceeds to another if statement nested inside.
2. Nested Condition Check:
   • This second if statement checks an additional condition.
   • If this nested condition is true, a specific block of code executes.
   • If false, a different block of code executes, placed immediately below.
3. Else Clause:
   • If the initial if condition is false, the flow moves to the else block.
   • This else block contains its own set of operations that execute when the primary condition fails.

Nested if with else Condition

Nested if statements with else conditions are especially useful when decisions require more than one criterion to be evaluated in a sequence. This structure allows developers to refine the decision process at each level, managing specific actions based on various conditions.

i = 0; 
# if condition 1
if i != 0:
    # condition 1
    if i > 0:
        print("Positive")
        
    # condition 2
    if i < 0:
        print("Negative")
else:
    print("Zero")
    

Zero