Nested for Loops in Java

Chapter 10

Nested for Loops in Java

Class 10 - Logix Kips ICSE Computer Applications with BlueJ

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Java Program: Java Output Programs

5 (i). What will be the value of sum after each of the following nested loops is executed?

int sum = 0;

for (int i = 0; i <= 10; i++)

    for (int j = 0; j <= 10; j++)

          sum += i;

5 (ii). What will be the value of sum after each of the following nested loops is executed?

int sum = 0;

for (int i = 1; i <= 3; i++)

    for (int j = 1; j <= 3; j++)

        sum = sum + (i + j);

Program Title 5 (i) : Value of sum After Nested Loops Execution in Java

int sum = 0;
for (int i = 0; i <= 10; i++)
    for (int j = 0; j <= 10; j++)
          sum += i;

605

📝 Explanation

Step 1: Understand the loops

• Outer loop: i runs from 0 to 10 → 11 values
• Inner loop: j runs from 0 to 10 → 11 times for each i

👉 For each value of i, the statement sum += i executes 11 times.

Step 2: Calculate contribution of each i

For a fixed i, total added = 11 × i

So total sum:

11 × (0 + 1 + 2 + 3 + . . . + 10)

We know:

0 + 1 + 2 + . . . + 10 = 55

Therefore:

sum=11×55=605sum = 11 × 55 = 605sum=11×55=605

✅ Final Answer (5 i)

      sum = 605

Explanation with Dry Run

The outer loop executes 11 times. For each iteration of outer loop, the inner loop executes 11 times. For every value of j, i is added to sum 11 times. Consider the following table for the value of sum with each value of i and j.

Program Title 5(ii) : Value of sum After Nested Loops Execution in Java

int sum = 0;
for (int i = 1; i <= 3; i++)
    for (int j = 1; j <= 3; j++)
        sum = sum + (i + j);
 

36

📝 Explanation

Step 1: Values of i and j

• i = 1, 2, 3
• j = 1, 2, 3

Total executions:

              3×3=9 times

Step 2: Expand all combinations

Now add all values:

               2 + 3 + 4 + 3 + 4 + 5 + 4 + 5 + 6 

Group properly:

              (2 + 3 + 4) + (3 + 4 + 5) + (4 + 5 + 6)   

               9 + 12 + 15 = 36

✅ Final Answer (5 ii)

      sum=36

Explanation with Dry Run Table

The outer loop executes 3 times. For each iteration of outer loop, the inner loop executes 3 times. For every value of j, i + j is added to sum 3 times. Consider the following table for the value of sum with each value of i and j.