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

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple do-while loop

What is the output of this C# code snippet?

C Sharp (C#)

int count = 0;
do
{
    Console.Write(count + " ");
    count++;
} while (count < 3);

A 0 1 2

B 1 2 3

C 0 1 2 3

D No output

💡 Hint

Remember, do-while executes the loop body before checking the condition.

The loop starts with count = 0, prints it, then increments. It repeats while count < 3, so it prints 0, 1, and 2.

❓ Predict Output

intermediate

Do-while loop with condition false initially

What will this C# code print?

C Sharp (C#)

int x = 5;
do
{
    Console.WriteLine("Inside loop");
    x++;
} while (x < 5);

A Inside loop

B No output

C

Inside loop
Inside loop

D Compilation error

💡 Hint

Do-while runs the loop body at least once even if the condition is false.

Even though x is 5 and condition x < 5 is false, the loop body runs once before checking condition.

🔧 Debug

advanced

Identify the infinite loop in do-while

Which option causes an infinite loop when run?

C Sharp (C#)

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

A

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

B

int i = 0;
do { Console.Write(i + " "); i += 2; } while (i < 3);

C

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

D

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

💡 Hint

Check if the loop variable changes inside the loop body.

Option D never changes i inside the loop, so condition i < 3 is always true, causing infinite loop.

❓ Predict Output

advanced

Value of variable after do-while loop

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

C Sharp (C#)

int sum = 0;
int n = 1;
do
{
    sum += n;
    n++;
} while (n <= 5);

A 10

B 15

C 5

D 0

💡 Hint

Sum numbers from 1 to 5 inclusive.

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

🧠 Conceptual

expert

Do-while loop execution guarantee

Which statement best describes the execution behavior of a do-while loop in C#?

A The loop body executes zero or more times depending on the condition.

B The loop body executes only if the condition is true at the start.

C The loop body executes at least once before the condition is checked.

D The loop body executes exactly once regardless of the condition.

💡 Hint

Think about how do-while differs from while loop.

Do-while loops always run the body once before checking the condition.