Do-while loop execution model in C Sharp (C#) - Step-by-Step Execution

Concept Flow - Do-while loop execution model

Start

↓

Execute body

↓

Check condition

↓

Exit

The do-while loop runs the code inside the loop first, then checks the condition. If true, it repeats; if false, it stops.

Execution Sample

C Sharp (C#)

int i = 1;
do {
    Console.WriteLine(i);
    i++;
} while (i <= 3);

This code prints numbers 1 to 3 using a do-while loop that runs the body before checking the condition.

Execution Table

Step	i value	Action	Condition (i <= 3)	Loop continues?	Output
1	1	Execute body: print i, increment i	1 <= 3 is True	Yes	1
2	2	Execute body: print i, increment i	2 <= 3 is True	Yes	2
3	3	Execute body: print i, increment i	3 <= 3 is True	Yes	3
4	4	Condition checked, body skipped	4 <= 3 is False	No

💡 At step 4, i is 4, condition 4 <= 3 is False, so loop stops.

Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
i	1	2	3	4	4

Key Moments - 3 Insights

Why does the loop body run even when the condition is false at the start?

Because in a do-while loop, the body runs first before the condition is checked, as shown in execution_table step 1.

When does the condition get checked in the do-while loop?

The condition is checked after the loop body runs, as seen in the 'Condition' column after each action in the execution_table.

What happens when the condition becomes false?

The loop stops immediately after the condition check shows false, as in execution_table step 4 where the loop exits.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of i when the loop stops?

A 3

B 4

C 1

D 0

💡 Hint

Check the 'i value' column at step 4 in the execution_table where the loop exits.

At which step does the condition first become false?

A Step 1

B Step 3

C Step 4

D Step 2

💡 Hint

Look at the 'Condition' column in the execution_table to find when condition is false.

If the initial value of i was 5, how many times would the loop body run?

A 1 time

B 5 times

C 0 times

D Infinite times

💡 Hint

Remember do-while runs the body once before checking condition; see key_moments about first run.

Concept Snapshot

do-while loop syntax:
 do {
   // code
 } while (condition);

Runs loop body first, then checks condition.
Repeats if condition true, stops if false.
Always runs at least once.

Full Transcript

This visual execution shows how a do-while loop works in C#. The loop starts by running the code inside the body once before checking the condition. After running the body, it checks if the condition is true. If yes, it repeats the body again. If no, it stops. The example code prints numbers 1 to 3. The variable i starts at 1 and increases by 1 each time. The loop runs while i is less than or equal to 3. The execution table shows each step: the value of i, the action taken, the condition check, whether the loop continues, and what is printed. The variable tracker shows how i changes after each loop. Key moments explain why the body runs first and when the loop stops. The quiz questions help check understanding of the loop's behavior and variable changes.