For loop basics in Go - Step-by-Step Execution

Concept Flow - For loop basics

Initialize i=0

↓

Check: i < 5?

No→EXIT

Yes↓

Execute body

↓

Update: i = i+1

↩Back to Check

The loop starts by setting i to 0, then checks if i is less than 5. If yes, it runs the loop body, then increases i by 1 and repeats. If no, it stops.

Execution Sample

Go

for i := 0; i < 5; i++ {
    fmt.Println(i)
}

This code prints numbers from 0 to 4 using a for loop.

Execution Table

Iteration	i	Condition i<5	Action	Output
1	0	true	Print i=0, i++	0
2	1	true	Print i=1, i++	1
3	2	true	Print i=2, i++	2
4	3	true	Print i=3, i++	3
5	4	true	Print i=4, i++	4
6	5	false	Exit loop

💡 i reaches 5, condition 5 < 5 is false, loop stops

Variable Tracker

Variable	Start	After 1	After 2	After 3	After 4	After 5	Final
i	0	1	2	3	4	5	5

Key Moments - 3 Insights

Why does the loop stop when i equals 5?

Because the condition i < 5 becomes false at iteration 6, as shown in the execution_table row 6.

Does the loop print the number 5?

No, the loop stops before printing 5 because the condition i < 5 is false when i is 5, as seen in execution_table row 6.

When is the variable i increased?

i is increased after printing in each iteration, before the next condition check, as shown in the Action column of the execution_table.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of i during iteration 3?

A 2

B 3

C 1

D 0

💡 Hint

Check the 'i' column in execution_table row 3.

At which iteration does the condition i < 5 become false?

A 5

B 6

C 4

D 1

💡 Hint

Look at the 'Condition i<5' column in execution_table row 6.

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

A 2 times

B 5 times

C 3 times

D 4 times

💡 Hint

Compare the condition i < 5 with i < 3 and count iterations accordingly.

Concept Snapshot

Go for loop syntax:
for initialization; condition; post {
    // code
}
Loop runs while condition is true.
Variable updates after each iteration.
Stops when condition is false.

Full Transcript

This visual trace shows a Go for loop starting with i=0. Each step checks if i is less than 5. If true, it prints i and then increases i by 1. This repeats until i reaches 5, when the condition fails and the loop stops. The variable tracker shows i's value changing from 0 up to 5. Key moments clarify why the loop stops before printing 5 and when i increments. The quiz tests understanding of variable values and loop stopping conditions.