Infinite loops in Go - Step-by-Step Execution

Concept Flow - Infinite loops

Start

↓

Check loop condition

↓

Condition true?

No→Exit loop

Yes↓

Execute loop body

↓

Update variables (optional)

↓

Check loop condition

The loop keeps running as long as the condition is true. If the condition never becomes false, the loop runs forever, causing an infinite loop.

Execution Sample

Go

package main
import "fmt"
func main() {
  for {
    fmt.Println("Looping forever")
  }
}

This Go program runs an infinite loop printing "Looping forever" endlessly.

Execution Table

Step	Loop Condition	Condition Result	Action	Output
1	for {}	Always true	Print "Looping forever"	Looping forever
2	for {}	Always true	Print "Looping forever"	Looping forever
3	for {}	Always true	Print "Looping forever"	Looping forever
...	for {}	Always true	Print "Looping forever"	Looping forever
∞	for {}	Always true	Print "Looping forever"	Looping forever

💡 No exit: loop condition is always true, so the loop never stops.

Variable Tracker

Variable	Start	After 1	After 2	After 3	...final
No variables	N/A	N/A	N/A	N/A	N/A

Key Moments - 2 Insights

Why does this loop never stop?

Because the loop condition is empty and always true (for {}), so the program never reaches an exit point as shown in every step of the execution_table.

Is there any variable changing to stop the loop?

No, there are no variables or conditions changing inside the loop, so nothing can make the loop stop, as confirmed by the variable_tracker showing no variables.

Visual Quiz - 3 Questions

Look at the execution table, what is the condition result at step 3?

A False

B Depends on variable

C Always true

D Unknown

💡 Hint

Check the 'Condition Result' column at step 3 in the execution_table.

At which step does the loop exit according to the execution table?

A Step 3

B Never

C Step 1

D Step 10

💡 Hint

Look at the exit_note and see if any step shows the loop stopping.

If we add a break statement inside the loop after printing, how would the execution table change?

A Loop would stop after step 1

B Loop would still run forever

C Loop would stop after step 3

D Loop would run twice then stop

💡 Hint

Adding break exits the loop immediately after first iteration, so check step 1 action and output.

Concept Snapshot

Infinite loops in Go:
- Use 'for {}' for an endless loop
- No condition means always true
- Loop runs forever unless broken
- Can cause program to hang
- Use break to exit loop manually

Full Transcript

This example shows an infinite loop in Go using 'for {}'. The loop condition is always true because it is empty, so the loop never stops. Each step prints "Looping forever" endlessly. There are no variables changing to stop the loop. Beginners often wonder why the loop never ends; it's because the condition never becomes false. Adding a break statement inside the loop can stop it. This trace helps visualize how the loop runs step by step without exit.

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