Break statement in Go - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the break statement do in Go?

The break statement immediately stops the execution of the nearest enclosing loop or switch statement and exits it.

beginner

In which Go control structures can you use the break statement?

You can use break inside for loops and switch statements to exit them early.

intermediate

What happens if you use break inside a nested loop?

The break statement only exits the innermost loop where it is used, not all outer loops.

advanced

How can you use break with labels in Go?

You can label loops and use break with the label name to exit an outer loop from inside an inner loop.

beginner

Example: What will this code print?

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

It will print:
1
2
Because when i becomes 3, the break stops the loop immediately.

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

A Does nothing special

B Stops the loop immediately and exits it

C Restarts the loop from the beginning

D Skips the current iteration and continues

The break statement stops the loop immediately and exits it.

Can break be used to exit a switch statement in Go?

A Yes, it exits the switch

B No, it only works in loops

C Only if the switch is inside a loop

D Only with labels

In Go, break can be used to exit a switch statement early.

What happens if you use break inside an inner loop nested in an outer loop?

A Only the inner loop stops

B Both loops stop

C Only the outer loop stops

D No loops stop

The break stops only the innermost loop where it is used.

How do you break out of an outer loop from inside an inner loop in Go?

A You cannot break outer loops

B Use <code>continue</code> with a label

C Use <code>return</code>

D Use <code>break</code> with a label

You label the outer loop and use break with that label to exit it.

What will this code print?

for i := 0; i < 3; i++ {
  for j := 0; j < 3; j++ {
    if j == 1 {
      break
    }
    fmt.Print(j)
  }
  fmt.Println(i)
}

A 0 0 1 2

B 0 0 0

C 00 01 02

D 0 1 2

The inner loop prints 0 then breaks when j == 1, then the outer loop prints i. So output is 001 012.

Explain how the break statement works in Go loops and switches.

Think about how to stop a repeating action early.

Describe how to use labels with break to exit outer loops in Go.

Labels help break out of nested loops.

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