Loop execution flow in Go - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of nested loops with continue

What is the output of this Go program?

Go

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

A 11 12 13 21 22 23 31 32 33

B 11 13 22 23 31 33

C 12 13 22 23 32 33

D 11 13 21 23 31 33

💡 Hint

Remember that continue skips the rest of the current loop iteration.

The inner loop skips printing when j == 2. So for each i, it prints j=1 and j=3 only.

❓ Predict Output

intermediate

Loop with break inside if condition

What will this Go program print?

Go

package main
import "fmt"
func main() {
    for i := 0; i < 5; i++ {
        if i == 3 {
            break
        }
        fmt.Print(i)
    }
}

A 0123

B 012

C 01234

D 123

💡 Hint

Break exits the loop immediately when the condition is met.

The loop prints numbers starting from 0. When i == 3, it breaks out of the loop, so it prints 0,1,2 only.

❓ Predict Output

advanced

Output of loop with labeled break

What is the output of this Go program?

Go

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

A 11 12 21

B 11 12 21 22 23

C 11 12 21 22

D 11 12 13 21 22 23 31 32 33

💡 Hint

The labeled break exits the outer loop when the condition is true.

When i*j > 3, the program breaks out of the outer loop completely. The last printed pair is 22 before breaking.

❓ Predict Output

advanced

Loop with post statement modifying loop variable

What will this Go program print?

Go

package main
import "fmt"
func main() {
    for i := 0; i < 5; i++ {
        fmt.Print(i)
        i++
    }
}

A 024

B 01234

C 135

D 0134

💡 Hint

Notice that i++ is called inside the loop body and also in the for statement.

The loop increments i twice each iteration: once in the body and once in the for statement. So it prints 0, 2, 4.

🧠 Conceptual

expert

Number of iterations in complex loop

Consider this Go code snippet. How many times will the inner loop's body execute?

for i := 1; i <= 4; i++ {
    for j := i; j <= 4; j++ {
        // loop body
    }
}

A 10

B 16

C 6

D 4

💡 Hint

Count the number of pairs (i,j) where j >= i and both go up to 4.

For i=1, j=1..4 (4 times); i=2, j=2..4 (3 times); i=3, j=3..4 (2 times); i=4, j=4..4 (1 time). Total = 4+3+2+1 = 10.