For loop as while in Go - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a for loop used as while

What is the output of this Go program that uses a for loop as a while loop?

Go

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

A 0 1 2

B 123

C 012

D Error: syntax error

💡 Hint

Remember that the loop runs while the condition is true and increments i each time.

The loop starts with i=0 and runs while i<3. It prints i each time without spaces, so output is '012'.

❓ Predict Output

intermediate

Counting down with for loop as while

What does this Go code print?

Go

package main
import "fmt"
func main() {
    i := 3
    for i > 0 {
        fmt.Print(i)
        i--
    }
}

A 3 2 1

B 123

C Error: missing semicolon

D 321

💡 Hint

The loop decreases i from 3 down to 1, printing each value.

The loop prints i starting at 3 and decreases until i is 0 (not printed). Output is '321'.

🔧 Debug

advanced

Identify the error in for loop as while

What error does this Go code produce?

Go

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

A Syntax error: missing semicolon

B Infinite loop

C Compile error: undefined variable i

D No error, prints 0 1 2

💡 Hint

Check if the loop variable changes inside the loop.

The variable i is never incremented, so the condition i < 3 is always true, causing an infinite loop.

🧠 Conceptual

advanced

Understanding for loop as while syntax

Which of these Go for loops correctly acts like a while loop that runs while x is less than 5?

A for x < 5 { x++ }

B for x < 5; x++ {}

C for x := 0; x < 5; x++ {}

D for ; x < 5; { x++ }

💡 Hint

Remember the syntax for a for loop with only a condition in Go.

Option A uses a condition only and is valid syntax for a for loop acting as a while loop. Option A is invalid syntax. Option A is a classic for loop with init, condition, and post. Option A is invalid syntax.

🚀 Application

expert

Predict the final value after for loop as while

What is the value of variable sum after running this Go code?

Go

package main
import "fmt"
func main() {
    sum := 0
    i := 1
    for i <= 5 {
        sum += i
        i += 2
    }
    fmt.Println(sum)
}

A 9

B 12

C 15

D Error: invalid syntax

💡 Hint

Add 1, then 3, then 5 to sum.

The loop adds i to sum while i <= 5. i takes values 1, 3, 5. Sum is 1+3+5=9.