Labelled break and continue in Go - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of labelled break in nested loops

What is the output of this Go program using a labelled break?

Go

package main
import "fmt"
func main() {
OuterLoop:
for i := 1; i <= 3; i++ {
    for j := 1; j <= 3; j++ {
        if i*j > 3 {
            break OuterLoop
        }
        fmt.Printf("%d,%d ", i, j)
    }
}
}

A 1,1 1,2 2,1

B 1,1 1,2 1,3 2,1

C 1,1 1,2 2,1 2,2

D 1,1 1,2 1,3 2,1 2,2

💡 Hint

Remember that labelled break exits the outer loop immediately.

The inner loop prints pairs until i*j > 3. When i=2 and j=2, 2*2=4 > 3, so break OuterLoop stops all loops. So output stops after printing 1,1 1,2 1,3 2,1.

❓ Predict Output

intermediate

Output of labelled continue in nested loops

What is the output of this Go program using a labelled continue?

Go

package main
import "fmt"
func main() {
Outer:
for i := 1; i <= 3; i++ {
    for j := 1; j <= 3; j++ {
        if i == j {
            continue Outer
        }
        fmt.Printf("%d,%d ", i, j)
    }
}
}

A 2,1 3,1 3,2

B 1,2 1,3 2,1 2,3 3,1

C 1,2 1,3 2,1 2,3 3,1 3,2 3,3

D 1,2 1,3 2,1 2,3 3,1 3,2

💡 Hint

Labelled continue skips to the next iteration of the outer loop, skipping remaining inner loop iterations.

When i == j, continue Outer skips remaining inner loop iterations and proceeds to the next outer loop iteration (i++). For i=1: skips at j=1 (no output). i=2: prints 2,1, skips at j=2. i=3: prints 3,1 3,2, skips at j=3. Output: 2,1 3,1 3,2

🔧 Debug

advanced

Identify the error with labelled break usage

What error does this Go code produce?

Go

package main
func main() {
    for i := 0; i < 3; i++ {
        if i == 1 {
            break Outer
        }
    }
}

A no error, program runs fine

B runtime panic: label not found

C compile error: undefined label Outer

D compile error: break statement not in loop or switch

💡 Hint

Labels must be declared before use.

The label Outer is not declared anywhere, so the compiler reports undefined label error.

❓ Predict Output

advanced

Effect of labelled continue on outer loop variable

What is the output of this Go program?

Go

package main
import "fmt"
func main() {
Outer:
for i := 1; i <= 2; i++ {
    for j := 1; j <= 3; j++ {
        if j == 2 {
            continue Outer
        }
        fmt.Printf("%d,%d ", i, j)
    }
}
}

A 1,1 2,1 2,3

B 1,1 2,1 2,2 2,3

C 1,1 1,3 2,1 2,3

D 1,1 2,1

💡 Hint

Labelled continue skips to next iteration of outer loop immediately.

When j == 2, continue Outer skips the rest of inner loop and increments i. So only j=1 prints for each i.

🧠 Conceptual

expert

Understanding labelled break and continue behavior

Which statement about labelled break and continue in Go is TRUE?

A Labelled break exits the loop with the matching label; labelled continue skips to the next iteration of the labelled loop.

B Labelled break and continue can only be used with for loops, not switch statements.

C Labelled break skips the current iteration of the labelled loop; labelled continue exits the labelled loop entirely.

D Labelled continue can be used without a label to skip the current iteration of the innermost loop.

💡 Hint

Think about what break and continue do normally and how labels change their target.

Labelled break exits the loop with the label; labelled continue skips to the next iteration of that labelled loop. They can be used with for and switch. Unlabelled continue skips current iteration of innermost loop.