While loop in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple while loop

What is the output of this Ruby code?

Ruby

i = 1
while i <= 3
  puts i
  i += 1
end

A

0
1
2
3

B

1
2

C

1
2
3
4

D

1
2
3

💡 Hint

Remember the loop runs while the condition is true.

The loop starts with i = 1 and prints i while i is less than or equal to 3. It prints 1, 2, and 3 each on a new line.

🧠 Conceptual

intermediate

Understanding loop exit condition

What will be the value of variable count after this code runs?

Ruby

count = 0
while count < 5
  count += 2
end

A 6

B 5

C 4

D Infinite loop

💡 Hint

Think about when the loop stops and the last increment.

The loop increments count by 2 starting from 0: 0 -> 2 -> 4 -> 6. When count becomes 6, the condition count < 5 is false, so the loop stops. The final value is 6.

🔧 Debug

advanced

Identify the error in this while loop

What error will this Ruby code produce when run?

Ruby

i = 0
while i < 3
  puts i
  i = i - 1
end

A Infinite loop

B SyntaxError

C TypeError

D No output

💡 Hint

Look at how the variable changes inside the loop.

The variable i starts at 0 and decreases by 1 each time. Since i < 3 is always true, the loop never ends, causing an infinite loop.

📝 Syntax

advanced

Which code snippet correctly uses a while loop?

Select the option that is syntactically correct Ruby code using a while loop to print numbers 1 to 3.

A

i = 1
while i <= 3:
  puts i
  i += 1

B

i = 1
while (i <= 3) {
  puts i
  i += 1
}

C

i = 1
while i <= 3
  puts i
  i += 1
end

D

i = 1
while i <= 3
  puts i
  i++
end

💡 Hint

Remember Ruby syntax for loops does not use ++ or braces.

Option C uses correct Ruby syntax. Option C uses i++ which is invalid in Ruby. Option C uses braces which are not used with while in Ruby. Option C uses a colon which is invalid syntax in Ruby.

🚀 Application

expert

Calculate sum using while loop

What is the value of sum after running this Ruby code?

Ruby

sum = 0
num = 1
while num <= 5
  sum += num
  num += 1
end

A 5

B 15

C 10

D 20

💡 Hint

Sum numbers from 1 to 5.

The loop adds numbers 1 through 5 to sum: 1+2+3+4+5 = 15.