Break and continue behavior in Swift

Introduction

Break and continue help control loops by stopping or skipping parts of the loop. They make your code easier to manage.

Stop a loop early when you find what you need, like searching for a name in a list.

Skip certain items in a loop, like ignoring empty strings when processing text.

Exit a loop when an error happens to avoid wrong results.

Skip processing for some numbers, like ignoring even numbers when counting odds.

Syntax

Swift

for item in collection {
    if conditionToStop {
        break
    }
    if conditionToSkip {
        continue
    }
    // other code
}

break stops the whole loop immediately.

continue skips the rest of the current loop cycle and moves to the next one.

Examples

This loop prints numbers until it reaches 3, then stops completely.

Swift

for number in 1...5 {
    if number == 3 {
        break
    }
    print(number)
}

This loop skips printing 3 but continues printing other numbers.

Swift

for number in 1...5 {
    if number == 3 {
        continue
    }
    print(number)
}

Sample Program

This program loops through numbers 1 to 5. It skips even numbers and stops completely when it finds 4.

Swift

let numbers = [1, 2, 3, 4, 5]

for number in numbers {
    if number == 4 {
        print("Found 4, stopping loop.")
        break
    }
    if number % 2 == 0 {
        print("Skipping even number: \(number)")
        continue
    }
    print("Processing number: \(number)")
}

Important Notes

Use break to exit loops early when you no longer need to continue.

Use continue to skip only the current loop cycle but keep looping.

Both help make loops more efficient and easier to read.

Summary

break stops the entire loop immediately.

continue skips the rest of the current loop cycle and moves to the next.

Use them to control loop flow clearly and simply.

Practice

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

easy

A. Restarts the loop from the beginning.

B. Skips the current iteration and continues with the next one.

C. Pauses the loop until a condition is met.

D. Stops the entire loop immediately and exits it.

Solution

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

   The break statement immediately stops the loop and exits it, no matter where it is in the loop.

2. Step 2: Compare with other options

   continue skips to the next iteration, but break stops the loop entirely. Restarting or pausing the loop is not the behavior of break.

3. Final Answer:

   Stops the entire loop immediately and exits it. -> Option D

4. Quick Check:

   break stops loop [OK]

Hint: Break means stop the loop completely [OK]

Common Mistakes:

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

2. Which of the following is the correct syntax to skip the current iteration in a Swift for loop?

easy

A. skip

B. continue

C. break

D. stop

Solution

1. Step 1: Identify the keyword to skip iteration

   In Swift, continue is used to skip the rest of the current loop iteration and move to the next one.

2. Step 2: Verify other options

   break stops the loop, skip and stop are not valid Swift keywords for loops.

3. Final Answer:

   continue -> Option B

4. Quick Check:

   Skip iteration = continue [OK]

Hint: Use continue to skip current loop step [OK]

Common Mistakes:

• Using break instead of continue
• Using non-existent keywords like skip or stop
• Confusing continue with break

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

for i in 1...5 {
    if i == 3 {
        break
    }
    print(i)
}

medium

A. 1 2

B. No output

C. 3 4 5

D. 1 2 3 4 5

Solution

1. Step 1: Analyze the loop and break condition

   The loop runs from 1 to 5. When i equals 3, break stops the loop immediately.

2. Step 2: Determine printed values before break

   Values 1 and 2 are printed before reaching 3. At 3, loop stops, so 3, 4, 5 are not printed.

3. Final Answer:

   1 2 -> Option A

4. Quick Check:

   Break stops at 3, prints before it [OK]

Hint: Break stops loop before printing 3 [OK]

Common Mistakes:

• Assuming break skips only current iteration
• Thinking all numbers print
• Confusing break with continue

4. Find the error in this Swift code snippet:

for i in 1...5 {
    if i == 3 {
        continue
    }
    if i == 6 {
        break
    }
    print(i)
}

medium

A. break should come before continue in the code.

B. continue cannot be used inside a for loop.

C. The loop will never break because i never reaches 6.

D. The range 1...5 is invalid.

Solution

1. Step 1: Check the loop range and conditions

   The loop runs from 1 to 5, so i will never be 6.

2. Step 2: Analyze the break condition

   Since i == 6 never occurs, the break statement will never execute, so the loop runs fully except skipping 3 due to continue.

3. Final Answer:

   The loop will never break because i never reaches 6. -> Option C

4. Quick Check:

   Break condition unreachable [OK]

Hint: Check if break condition can ever be true [OK]

Common Mistakes:

• Thinking continue is invalid in for loops
• Assuming break runs before continue always
• Not checking loop range carefully

5. You want to print all numbers from 1 to 10 except 5 and stop printing after 8. Which code snippet correctly uses break and continue in Swift?

hard

A. for i in 1...10 {
if i == 5 { continue }
if i > 8 { break }
print(i)
}

B. for i in 1...10 {
if i == 5 { break }
if i > 8 { continue }
print(i)
}

C. for i in 1...10 {
if i == 5 { continue }
if i > 7 { continue }
print(i)
}

D. for i in 1...10 {
if i == 5 { break }
if i > 8 { break }
print(i)
}

Solution

1. Step 1: Understand requirements

   Skip printing 5 (use continue) and stop printing after 8 (use break when > 8).

2. Step 2: Check each option

   for i in 1...10 { if i == 5 { continue } if i > 8 { break } print(i) } uses continue to skip 5 and break to stop after 8, matching requirements exactly.

3. Final Answer:

   for i in 1...10 { if i == 5 { continue } if i > 8 { break } print(i) } -> Option A

4. Quick Check:

   Continue skips 5, break stops loop after 8 [OK]

Hint: Continue skips, break stops loop [OK]

Common Mistakes:

• Using break to skip 5 instead of continue
• Using continue to stop loop after 8
• Mixing order of break and continue incorrectly