Why loops are needed in Go - Challenge Your Understanding

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple for loop in Go

What is the output of this Go program?

Go

package main
import "fmt"
func main() {
    for i := 1; i <= 3; i++ {
        fmt.Print(i, " ")
    }
}

A 1 2 3

B 1 2 3 4

C 0 1 2 3

D 123

💡 Hint

Look at the loop start and end values and what is printed inside the loop.

The loop starts at 1 and runs while i is less than or equal to 3, printing i and a space each time. So it prints '1 2 3 '.

🧠 Conceptual

intermediate

Why use loops instead of repeating code?

Why do programmers use loops instead of writing the same code many times?

A Loops are only used to confuse beginners.

B Loops make the program run slower but look nicer.

C Loops let us repeat actions easily without writing code again and again.

D Loops are used to stop the program from running.

💡 Hint

Think about what happens if you want to do the same thing many times.

Loops help repeat tasks without copying code multiple times, making programs shorter and easier to change.

❓ Predict Output

advanced

Output of nested loops in Go

What does this Go program print?

Go

package main
import "fmt"
func main() {
    for i := 1; i <= 2; i++ {
        for j := 1; j <= 2; j++ {
            fmt.Print(i*j, " ")
        }
    }
}

A 1 2 3 4

B 1 2 2 4

C 1 1 2 2

D 2 4 2 4

💡 Hint

Multiply i and j for each pair in the nested loops.

The outer loop runs i=1,2. For each i, inner loop runs j=1,2. The products are 1*1=1, 1*2=2, 2*1=2, 2*2=4 printed in order.

🔧 Debug

advanced

Identify the error in this Go loop

What error does this Go code cause?

Go

package main
import "fmt"
func main() {
    for i := 0; i < 3; i++
        fmt.Println(i)
}

A Syntax error: missing semicolon after for statement

B Runtime error: index out of range

C No error, prints 0 1 2

D Syntax error: missing braces {} around loop body

💡 Hint

Check if the loop body is properly enclosed.

In Go, the for loop body must be inside braces {}. Without them, the code causes a syntax error.

🚀 Application

expert

Count how many times a loop runs

How many times does this loop run?

Go

package main
import "fmt"
func main() {
    count := 0
    for i := 10; i > 0; i -= 3 {
        count++
    }
    fmt.Println(count)
}

A 4

B 6

C 5

D 3

💡 Hint

Start at 10 and subtract 3 each time until i is no longer greater than 0.

The loop runs while i > 0: i=10,7,4,1 then stops when i= -2. So it runs 4 times.