Nested Loops

1. What are Nested Loops?

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Formal Definition

A nested loop is a loop that is placed inside the body of another loop.

The loop that contains another loop is called the outer loop, and the loop inside it is called the inner loop.

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In simple words:

When one loop runs completely inside another loop, it is called a nested loop.

Key Concept

• The outer loop controls how many times the inner loop will run.
• The inner loop completes all its iterations for each single iteration of the outer loop.

Real-World Analogy

Analogy 1: School Timetable

• Imagine a school day (outer loop)
• Inside each day, there are periods (inner loop)

For each day:
    For each period:
        Teach a subject

Each period finishes completely before moving to the next day.

Analogy 2: Rows and Columns in a Classroom

• Rows → outer loop
• Benches in each row → inner loop

To count benches:

• First row → count all benches
• Second row → count all benches
• And so on…