Nested loop execution in C Sharp (C#) - Step-by-Step Execution

Concept Flow - Nested loop execution

Start Outer Loop i=0

↓

Start Inner Loop j=0

↓

Execute Inner Loop Body

↓

Update j = j + 1

↓

Check j < limit?

No→End Inner Loop

Yes↓

Update i = i + 1

↓

Check i < limit?

No→End Outer Loop

↩Back to Execute Inner Loop Body

The outer loop starts and for each iteration, the inner loop runs completely before the outer loop moves to the next iteration.

Execution Sample

C Sharp (C#)

for (int i = 0; i < 2; i++) {
    for (int j = 0; j < 3; j++) {
        Console.WriteLine($"i={i}, j={j}");
    }
}

This code prints pairs of i and j values for nested loops where i runs 0 to 1 and j runs 0 to 2.

Execution Table

Step	i	j	Condition i<2	Condition j<3	Action	Output
1	0	0	True	True	Print i=0, j=0	i=0, j=0
2	0	1	True	True	Print i=0, j=1	i=0, j=1
3	0	2	True	True	Print i=0, j=2	i=0, j=2
4	0	3	True	False	Inner loop ends, increment i
5	1	0	True	True	Print i=1, j=0	i=1, j=0
6	1	1	True	True	Print i=1, j=1	i=1, j=1
7	1	2	True	True	Print i=1, j=2	i=1, j=2
8	1	3	True	False	Inner loop ends, increment i
9	2	0	False	N/A	Outer loop ends

💡 i reaches 2, condition i<2 is False, so outer loop stops

Variable Tracker

Variable	Start	After 1	After 2	After 3	After 4	After 5	After 6	After 7	Final
i	0	0	0	0	1	1	1	1	2
j	0	1	2	3	0	1	2	3	N/A

Key Moments - 2 Insights

Why does the inner loop run completely for each value of i before i increments?

Because the outer loop waits for the inner loop to finish all its iterations (j from 0 to 2) before moving to the next i value, as shown in execution_table rows 1-4 and 5-8.

Why does j reset to 0 when the inner loop starts again?

Each time the outer loop increments i, the inner loop starts fresh with j=0, as seen in execution_table rows 4 to 5 and 8 to 9.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of j at step 6?

A 0

B 1

C 2

D 3

💡 Hint

Check the 'j' column in execution_table row 6.

At which step does the outer loop condition become false?

A Step 9

B Step 8

C Step 4

D Step 5

💡 Hint

Look at the 'Condition i<2' column and the exit_note.

If the inner loop condition changed to j < 2, how many times would the inner loop print per outer loop iteration?

A 1 time

B 3 times

C 2 times

D 0 times

💡 Hint

Refer to the inner loop condition 'j < 3' in execution_table and imagine changing it to 'j < 2'.

Concept Snapshot

Nested loops run one inside the other.
Outer loop runs once per iteration.
Inner loop runs fully each outer iteration.
Inner loop variable resets each time.
Use nested loops to handle grids or pairs.

Full Transcript

This example shows nested loops in C#. The outer loop variable i runs from 0 to 1. For each i, the inner loop variable j runs from 0 to 2. Each pair i and j is printed. The inner loop completes all its iterations before the outer loop increments i. When j reaches 3, the inner loop ends and i increments. When i reaches 2, the outer loop ends. Variables i and j change as shown in the variable tracker. This helps understand how nested loops work step-by-step.