While loop execution model in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple while loop

What is the output of this C# code snippet?

C Sharp (C#)

int i = 0;
while (i < 3)
{
    Console.Write(i);
    i++;
}

A 012

B 123

C 0 1 2

D 0123

💡 Hint

Remember the loop runs while i is less than 3 and increments i each time.

The loop starts with i=0 and prints i before incrementing. It prints 0, then 1, then 2, then stops because i becomes 3.

❓ Predict Output

intermediate

While loop with break statement

What will be printed by this C# code?

C Sharp (C#)

int count = 0;
while (count < 5)
{
    if (count == 3) break;
    Console.Write(count);
    count++;
}

A 01234

B 0123

C 012

D 123

💡 Hint

The break stops the loop when count equals 3.

The loop prints 0, 1, 2 and then breaks when count is 3, so 3 and 4 are not printed.

🔧 Debug

advanced

Identify the infinite loop

Which option causes an infinite loop when run?

C Sharp (C#)

int x = 0;
while (x < 5)
{
    Console.Write(x);
    // missing increment
}

A

int x = 0;
while (x < 5)
{
    Console.Write(x);
}

B

int x = 0;
while (x < 5)
{
    Console.Write(x);
    x++;
}

C

int x = 0;
while (x < 5)
{
    x++;
    Console.Write(x);
}

D

int x = 0;
while (x <= 5)
{
    Console.Write(x);
    x++;
}

💡 Hint

Check if the loop variable changes inside the loop.

Option A never increments x, so x stays 0 and the condition x < 5 is always true, causing an infinite loop.

❓ Predict Output

advanced

While loop with nested condition

What is the output of this code?

C Sharp (C#)

int i = 0;
while (i < 5)
{
    if (i % 2 == 0)
        Console.Write(i);
    i++;
}

A 246

B 135

C 01234

D 024

💡 Hint

Only print i when it is even.

The loop prints i only when i is even (0, 2, 4). Odd numbers are skipped.

❓ Predict Output

expert

While loop with complex condition and post-loop value

What is the value of variable 'result' after this code runs?

C Sharp (C#)

int i = 1;
int result = 0;
while (i < 10)
{
    if (i % 3 == 0)
        result += i;
    i += 2;
}

A 21

B 12

C 15

D 18

💡 Hint

Add i to result only if i is divisible by 3, increment i by 2 each time.

i takes values 1,3,5,7,9. Only 3 and 9 are divisible by 3. Sum is 3 + 9 = 12.