Loop execution flow - Step-by-Step Execution

Concept Flow - Loop execution flow

Initialize loop variable

↓

Check loop condition

No→Exit loop

Yes↓

Execute loop body

↓

Update loop variable

↩Back to Check loop condition

This flow shows how a loop starts by setting a variable, checks if it should continue, runs the loop body if yes, updates the variable, and repeats until the condition is false.

Execution Sample

C

int i = 0;
while (i < 3) {
    printf("%d\n", i);
    i++;
}

This code prints numbers 0, 1, and 2 by looping while i is less than 3.

Execution Table

Step	i value	Condition (i < 3)	Condition Result	Action	Output
1	0	0 < 3	True	Print 0, i = i + 1	0
2	1	1 < 3	True	Print 1, i = i + 1	1
3	2	2 < 3	True	Print 2, i = i + 1	2
4	3	3 < 3	False	Exit loop

💡 i reaches 3, condition 3 < 3 is False, loop ends

Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
i	0	1	2	3	3

Key Moments - 2 Insights

Why does the loop stop when i is 3 even though 3 is a number?

The loop condition checks if i is less than 3. When i equals 3, the condition 3 < 3 is false, so the loop stops as shown in step 4 of the execution table.

When is the value of i updated during the loop?

i is updated after printing in each loop iteration, as shown in the 'Action' column of the execution table where i = i + 1 happens after printing.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of i at step 2?

A 1

B 0

C 2

D 3

💡 Hint

Check the 'i value' column in row for step 2 in the execution table.

At which step does the loop condition become false?

A Step 3

B Step 4

C Step 2

D Step 1

💡 Hint

Look at the 'Condition Result' column and find where it says False.

If we change the loop condition to i <= 3, how many times will the loop run?

A 2 times

B 3 times

C 4 times

D Infinite times

💡 Hint

Consider that i starts at 0 and runs while i is less than or equal to 3.

Concept Snapshot

Loop execution flow in C:
1. Initialize loop variable.
2. Check condition before each iteration.
3. If true, run loop body.
4. Update variable.
5. Repeat until condition is false.
Example: while(i < 3) { ... } runs 3 times for i=0,1,2.

Full Transcript

This visual execution shows how a loop in C works step-by-step. First, the loop variable i is set to 0. Then the loop checks if i is less than 3. If yes, it prints i and increases i by 1. This repeats until i reaches 3, when the condition becomes false and the loop stops. The execution table tracks each step, showing i's value, the condition check, and the output. Key points include understanding when the loop stops and when the variable updates. The quiz tests understanding of these steps.