While loop in Swift - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple while loop

What is the output of the following Swift code?

Swift

var count = 3
while count > 0 {
    print(count)
    count -= 1
}

A

3
2
1

B

1
2
3

C

0
1
2
3

D

3
2
1
0

💡 Hint

Remember the loop runs while count is greater than zero and decreases count each time.

The loop starts with count = 3 and prints it, then decreases count by 1. It continues until count is no longer greater than 0, so it prints 3, 2, and 1.

❓ Predict Output

intermediate

While loop with break statement

What will be printed by this Swift code?

Swift

var i = 1
while i <= 5 {
    if i == 3 {
        break
    }
    print(i)
    i += 1
}

A

1
2

B

1
2
3

C

1
2
3
4
5

D

3
4
5

💡 Hint

The break statement stops the loop immediately when i equals 3.

The loop prints i starting from 1. When i becomes 3, the break stops the loop before printing 3, so only 1 and 2 are printed.

❓ Predict Output

advanced

While loop with continue statement

What is the output of this Swift code snippet?

Swift

var n = 0
while n < 5 {
    n += 1
    if n == 3 {
        continue
    }
    print(n)
}

A

1
2
3
4

B

1
2
3
4
5

C

2
3
4
5

D

1
2
4
5

💡 Hint

The continue skips printing when n equals 3.

The loop increments n first. When n is 3, continue skips the print statement, so 3 is not printed. All other numbers from 1 to 5 except 3 are printed.

🧠 Conceptual

advanced

Understanding while loop condition

What happens if the condition in a Swift while loop is initially false?

A The loop body runs once before checking the condition.

B The loop body never runs.

C The loop runs infinitely.

D The loop runs twice.

💡 Hint

Think about when the condition is checked in a while loop.

A while loop checks the condition before running the loop body. If the condition is false at the start, the loop body does not run at all.

❓ Predict Output

expert

Counting iterations in a while loop

What is the value of variable 'count' after running this Swift code?

Swift

var count = 0
var x = 10
while x > 0 {
    if x % 3 == 0 {
        x -= 2
    } else {
        x -= 1
    }
    count += 1
}

A 9

B 8

C 7

D 10

💡 Hint

Track how x changes each loop and count how many times the loop runs.

Starting from x=10, the loop decreases x by 1 if x is not divisible by 3, or by 2 if it is. Counting iterations until x <= 0 gives 7.