C Nested Loops

🔁🔁 C Nested Loops (Beginner → Advanced)

In C language, nested loops mean one loop inside another loop.
They are mainly used for patterns, matrices, tables, searching, and DSA problems.

1️⃣ What is a Nested Loop?

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

📌 Outer loop controls rows
📌 Inner loop controls columns

2️⃣ Basic Nested for Loop Example ⭐

Output

3️⃣ Nested Loop Execution Flow (Very Important)

✔ Inner loop runs completely for each outer loop iteration
✔ Total executions = 3 × 3 = 9

4️⃣ Nested Loops with Different Loop Types

for inside while

✔ Any loop can be nested inside another

5️⃣ Pattern Programs (Most Common Use) ⭐

🔹 Right-Angle Triangle

🔹 Number Pattern

6️⃣ Nested Loops with Arrays ⭐

2D Array Traversal

✔ Used in matrix operations

7️⃣ break in Nested Loops 🔥

✔ break exits only inner loop

8️⃣ continue in Nested Loops

✔ Skips only j == 2

9️⃣ Time Complexity of Nested Loops ⭐

📌 Very important in DSA & interviews

🔟 Common Mistakes ❌

❌ Wrong loop bounds
❌ Infinite loops
❌ Misplaced break / continue
❌ Forgetting newline after inner loop

📌 Interview Questions (Must Prepare)

1. What is nested loop?

2. How many times inner loop runs?

3. Effect of break in nested loop?

4. Time complexity of nested loops?

5. Can while be nested inside for?

🔥 Real-Life Use Cases

• Matrix calculations

• Pattern printing

• Multiplication tables

• Grid-based problems

• Image processing

✅ Summary

✔ Nested loops = loop inside loop
✔ Inner loop runs fully per outer iteration
✔ Commonly used with 2D arrays
✔ Pattern programs rely on nested loops
✔ Critical for DSA & interviews