Break statement in Go - Step-by-Step Execution

Concept Flow - Break statement

Start Loop

↓

Check Condition

Yes↓

Execute Loop Body

↓

Check Break Condition

↓

Break Loop

↓

End Loop

The loop starts and runs while the condition is true. Inside, if the break condition is met, the loop stops immediately.

Execution Sample

Go

package main
import "fmt"
func main() {
  for i := 1; i <= 5; i++ {
    if i == 3 {
      break
    }
    fmt.Println(i)
  }
}

This code prints numbers 1 and 2, then stops the loop when i equals 3 using break.

Execution Table

Iteration	i	Condition i <= 5	Break Condition i == 3	Action	Output
1	1	true	false	Print 1	1
2	2	true	false	Print 2	2
3	3	true	true	Break loop
4	-	Loop exited	-	-	-

💡 Loop stops at iteration 3 because break condition i == 3 is true.

Variable Tracker

Variable	Start	After 1	After 2	After 3 (break)	Final
i	-	1	2	3	3

Key Moments - 2 Insights

Why does the loop stop printing after i equals 3 even though the loop condition i <= 5 is true?

Because the break statement runs when i == 3 (see execution_table row 3), it immediately exits the loop before printing.

Does the break statement skip only the current iteration or the entire loop?

The break statement stops the entire loop immediately, not just skipping one iteration (see execution_table row 3 action).

Visual Quiz - 3 Questions

Look at the execution table, what is the value of i when the break statement is executed?

A 1

B 2

C 3

D 4

💡 Hint

Check the 'Break Condition i == 3' column in row 3 of the execution_table.

At which iteration does the loop stop running?

A After iteration 2

B At iteration 3

C At iteration 4

D After iteration 5

💡 Hint

Look at the 'Action' column in the execution_table where it says 'Break loop'.

If the break condition was changed to i == 4, what would be the last number printed?

A 4

B 5

C 3

D 2

💡 Hint

Think about when the break would stop the loop and what numbers print before that (see variable_tracker and execution_table).

Concept Snapshot

Break statement in Go:
- Used inside loops to stop the loop immediately.
- Syntax: break
- When break runs, loop exits even if condition is true.
- Useful to stop early based on a condition.
- Example: if i == 3 { break } stops loop when i is 3.

Full Transcript

This visual execution shows how the break statement works in a Go for loop. The loop runs from i = 1 to 5. Each iteration prints i unless i equals 3. When i is 3, the break statement runs and stops the loop immediately. This means the loop does not continue to 4 or 5. The variable i changes from 1 to 3, and the loop exits at 3. The key moment is understanding that break stops the whole loop, not just one iteration. The quiz questions help check your understanding of when and why the loop stops.

Practice

1. What does the break statement do inside a loop in Go?

easy

A. It pauses the loop for a moment and then continues.

B. It skips the current iteration and moves to the next one.

C. It immediately stops the loop and continues after it.

D. It restarts the loop from the beginning.

Solution

1. Step 1: Understand the role of break in loops

   The break statement is used to exit a loop immediately, stopping any further iterations.

2. Step 2: Compare with other loop controls

   Unlike continue which skips to the next iteration, break stops the loop entirely and moves on.

3. Final Answer:

   It immediately stops the loop and continues after it. -> Option C

4. Quick Check:

   Break stops loop = It immediately stops the loop and continues after it. [OK]

Hint: Break stops loop immediately, no more repeats [OK]

Common Mistakes:

• Confusing break with continue
• Thinking break pauses the loop
• Assuming break restarts the loop

2. Which of the following is the correct syntax to use break inside a for loop in Go?

easy

A. for i := 0; i < 5; i++ { if i == 3 { exit } }

B. for i := 0; i < 5; i++ { if i == 3 { stop } }

C. for i := 0; i < 5; i++ { if i == 3 { continue } }

D. for i := 0; i < 5; i++ { if i == 3 { break } }

Solution

1. Step 1: Identify the correct keyword for stopping a loop

   In Go, break is the keyword used to exit a loop early.

2. Step 2: Check syntax correctness

   for i := 0; i < 5; i++ { if i == 3 { break } } uses break correctly inside an if statement within the for loop.

3. Final Answer:

   for i := 0; i < 5; i++ { if i == 3 { break } } -> Option D

4. Quick Check:

   Correct break syntax = for i := 0; i < 5; i++ { if i == 3 { break } } [OK]

Hint: Use 'break' keyword exactly to stop loops [OK]

Common Mistakes:

• Using 'stop' or 'exit' instead of 'break'
• Confusing 'continue' with 'break'
• Missing curly braces around break

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

for i := 1; i <= 5; i++ {
    if i == 3 {
        break
    }
    fmt.Print(i, " ")
}

medium

A. 1 2 3 4 5

B. 1 2

C. 3 4 5

D. 1 2 3

Solution

1. Step 1: Trace the loop iterations

   The loop starts at i=1 and prints i. When i=3, the break stops the loop immediately.

2. Step 2: Determine printed values before break

   Values printed before break are 1 and 2, then loop stops before printing 3.

3. Final Answer:

   1 2 -> Option B

4. Quick Check:

   Break at 3 stops loop = 1 2 [OK]

Hint: Break stops before printing 3, so only 1 and 2 print [OK]

Common Mistakes:

• Including 3 in output
• Printing all numbers ignoring break
• Confusing break with continue

4. Find the error in this Go code snippet using break:

for i := 0; i < 5; i++ {
    if i == 2 {
        break 2
    }
    fmt.Println(i)
}

medium

A. Using break with a number is invalid in Go.

B. The loop condition is wrong.

C. fmt.Println is not imported.

D. The break statement should be continue.

Solution

1. Step 1: Understand break usage in Go

   Go's break does not accept a number to break multiple loops; it only breaks the closest loop.

2. Step 2: Identify invalid syntax

   Using break 2 causes a syntax error because Go does not support labeled breaks with numbers.

3. Final Answer:

   Using break with a number is invalid in Go. -> Option A

4. Quick Check:

   Break with number invalid = Using break with a number is invalid in Go. [OK]

Hint: Go break never takes a number, only plain break [OK]

Common Mistakes:

• Trying to break multiple loops with a number
• Confusing Go with other languages like JavaScript
• Ignoring syntax errors from break usage

5. Given nested loops, how can you use break to exit only the inner loop in Go?

for i := 1; i <= 3; i++ {
    for j := 1; j <= 3; j++ {
        if j == 2 {
            break
        }
        fmt.Printf("%d,%d ", i, j)
    }
}

What will be the output?

hard

A. 1,1 2,1 3,1

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

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

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

Solution

1. Step 1: Understand break in nested loops

   The break inside the inner loop stops only that inner loop when j == 2.

2. Step 2: Trace output for each iteration

   For each i, inner loop prints when j=1, then breaks at j=2, so output is pairs with j=1 only.

3. Final Answer:

   1,1 2,1 3,1 -> Option A

4. Quick Check:

   Break stops inner loop only = 1,1 2,1 3,1 [OK]

Hint: Break stops only closest loop, inner loop ends early [OK]

Common Mistakes:

• Thinking break exits both loops
• Expecting all j values printed
• Confusing break with continue