Infinite loops in Go - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an infinite loop that prints "Hello" repeatedly.

Go

package main

import "fmt"

func main() {
    for [1] {
        fmt.Println("Hello")
    }
}

Drag options to blanks, or click blank then click option'

Atrue

Bfalse

Ci < 5

Di == 0

Attempts:

3 left

💡 Hint

Common Mistakes

Using a condition that becomes false eventually, so the loop stops.

Using false which never runs the loop.

Using true in the for loop condition creates an infinite loop in Go.

2fill in blank

medium

Complete the code to create an infinite loop using the classic for loop syntax.

Go

package main

import "fmt"

func main() {
    for [1] {
        fmt.Println("Looping forever")
    }
}

Drag options to blanks, or click blank then click option'

Ai := 0; i < 10; i++

Bi == 0

Ci < 5

D;;

Attempts:

3 left

💡 Hint

Common Mistakes

Putting a condition that eventually becomes false.

Using a normal for loop with limits.

In Go, a for loop with empty initialization, condition, and post statements (for ;;) runs infinitely.

3fill in blank

hard

Fix the error in the infinite loop code so it compiles and runs correctly.

Go

package main

import "fmt"

func main() {
    for [1] {
        fmt.Println("Running")
    }
}

Drag options to blanks, or click blank then click option'

A1 == 1

BTrue

Ctrue

Dfor

Attempts:

3 left

💡 Hint

Common Mistakes

Using uppercase True instead of lowercase true.

Putting for inside the loop condition.

Go uses lowercase true for boolean true. Using True causes a compile error.

4fill in blank

hard

Fill both blanks to create an infinite loop that prints numbers starting from 1.

Go

package main

import "fmt"

func main() {
    i := 1
    for [1] {
        fmt.Println(i)
        i[2]
    }
}

Drag options to blanks, or click blank then click option'

Atrue

B++

C+=

D--

Attempts:

3 left

💡 Hint

Common Mistakes

Using ++ which is a statement, not an expression.

Using -- which decreases the number.

The loop condition true makes the loop infinite. Using i += 1 increases i by 1 each time.

5fill in blank

hard

Fill all three blanks to create an infinite loop that prints "Go!" every second.

Go

package main

import (
    "fmt"
    "time"
)

func main() {
    for [1] {
        fmt.Println([2])
        time.Sleep([3])
    }
}

Drag options to blanks, or click blank then click option'

Atrue

B"Go!"

Ctime.Second

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using false which stops the loop immediately.

Forgetting to import time package.

Using a string without quotes.

The loop condition true makes it infinite. Printing "Go!" shows the message. time.Sleep(time.Second) pauses for one second each loop.

Practice

1. What does the following Go code do?

for { }

easy

A. Runs an infinite loop that never stops

B. Runs a loop 10 times

C. Runs a loop only once

D. Causes a syntax error

Solution

1. Step 1: Understand the loop syntax

   The code uses for { } which is Go's way to write an infinite loop without conditions.

2. Step 2: Analyze loop behavior

   Since there is no break or condition, the loop runs forever without stopping.

3. Final Answer:

   Runs an infinite loop that never stops -> Option A

4. Quick Check:

   for { } means infinite loop [OK]

Hint: for { } always means infinite loop in Go [OK]

Common Mistakes:

• Thinking it runs a fixed number of times
• Assuming it causes a syntax error
• Confusing with loops that have conditions

2. Which of the following is the correct syntax for an infinite loop in Go?

easy

A. for i := 0; i < 10; i++ { }

B. loop forever { }

C. for { }

D. while true { }

Solution

1. Step 1: Review Go loop syntax

   Go does not have a while or loop keyword; infinite loops use for { }.

2. Step 2: Identify correct infinite loop

   for { } uses for { }, which is the correct infinite loop syntax in Go.

3. Final Answer:

   for { } -> Option C

4. Quick Check:

   Go infinite loop syntax = for { } [OK]

Hint: Remember: Go uses for { } for infinite loops [OK]

Common Mistakes:

• Using while or loop keywords (not in Go)
• Confusing for loops with conditions as infinite
• Syntax errors from invalid keywords

3. What will be the output of this Go program?

package main
import "fmt"
func main() {
  count := 0
  for {
    if count == 3 {
      break
    }
    fmt.Println(count)
    count++
  }
}

medium

A. 0 1 2

B. 0 1 2 3

C. Infinite printing of numbers

D. No output

Solution

1. Step 1: Understand loop and break condition

   The loop runs infinitely but breaks when count equals 3.

2. Step 2: Trace output values

   It prints count values 0, 1, 2 then breaks before printing 3.

3. Final Answer:

   0 1 2 -> Option A

4. Quick Check:

   Loop breaks at count==3, prints 0 to 2 [OK]

Hint: Break stops infinite loop at condition [OK]

Common Mistakes:

• Expecting 3 to be printed
• Thinking loop runs forever
• Ignoring break statement

4. Identify the problem in this Go code that causes an infinite loop and fix it:

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

medium

A. Add break statement without increment

B. Change for to for { }

C. Remove the loop entirely

D. Add i++ inside the loop to increment i

Solution

1. Step 1: Identify loop condition and variable

   The loop runs while i < 5 but i is never changed inside the loop.

2. Step 2: Fix infinite loop by incrementing i

   Adding i++ inside the loop updates i, allowing the loop to end.

3. Final Answer:

   Add i++ inside the loop to increment i -> Option D

4. Quick Check:

   Increment loop variable to avoid infinite loop [OK]

Hint: Always update loop variable to prevent infinite loops [OK]

Common Mistakes:

• Forgetting to increment loop variable
• Adding break without changing i causes infinite loop
• Changing loop to infinite loop syntax accidentally

5. How can you safely implement an infinite loop in Go that stops after 5 seconds?

hard

A. Use for i := 0; i < 5; i++ { }

B. Use for { } with time.After and break when 5 seconds pass

C. Use while true with a timer

D. Use for { } without any break or condition

Solution

1. Step 1: Understand infinite loop with timeout

   Use for { } for infinite loop and time.After to wait 5 seconds.

2. Step 2: Break loop after 5 seconds

   Inside loop, check if 5 seconds passed and use break to stop loop safely.

3. Final Answer:

   Use for { } with time.After and break when 5 seconds pass -> Option B

4. Quick Check:

   Infinite loop + timer + break = safe stop [OK]

Hint: Combine for { } with timer and break to stop [OK]

Common Mistakes:

• Using invalid while syntax
• Not breaking loop causes infinite run
• Using fixed count loop instead of infinite