# C While Loop MCQ Questions and Answers

## 1. What is the primary characteristic of a 'while' loop in C?

a) The loop executes at least once
b) The condition is checked at the end of the loop
c) The loop may not execute at all if the condition is false initially
d) The loop executes an indefinite number of times

c) The loop may not execute at all if the condition is false initially

### Explanation:

A 'while' loop in C checks the condition before the loop body is executed. If the condition is false initially, the loop body does not execute at all.

## 2. How does a 'do...while' loop differ from a 'while' loop in C?

a) The 'do...while' loop checks the condition at the beginning
b) The 'do...while' loop executes at least once regardless of the condition
c) The 'do...while' loop cannot use a break statement
d) The 'do...while' loop is faster than the 'while' loop

b) The 'do...while' loop executes at least once regardless of the condition

### Explanation:

The 'do...while' loop in C checks the condition after the loop body has executed, ensuring that the loop body is executed at least once.

## 3. What is the correct syntax for a 'while' loop in C?

a) while condition { statements; }
b) while (condition) { statements; }
c) while (condition) statements;
d) Both b) and c) are correct

d) Both b) and c) are correct

### Explanation:

The correct syntax for a 'while' loop includes the 'while' keyword followed by the condition in parentheses and the loop body either in braces or as a single statement.

## 4. What is the correct syntax for a 'do...while' loop in C?

a) do { statements; } while (condition);
b) do (condition) { statements; };
c) do { statements; } until (condition);
d) do while (condition) { statements; };

a) do { statements; } while (condition);

### Explanation:

The 'do...while' loop begins with 'do', followed by the loop body in braces, and ends with 'while' and the condition in parentheses, followed by a semicolon.

## 5. Which type of loop is ideal when the number of iterations is not known in advance?

a) For loop
b) While loop
c) Do/while loop
d) Both b) and c) are suitable

d) Both b) and c) are suitable

### Explanation:

While and do/while loops are ideal for situations where the number of iterations is not predetermined, as they depend on a condition rather than a counter.

## 6. In a 'while' loop, if the condition never becomes false, what happens?

a) The loop exits after a certain number of iterations
b) The loop continues indefinitely, creating an infinite loop
c) The loop skips to the next section of code
d) An error is thrown by the compiler

b) The loop continues indefinitely, creating an infinite loop

### Explanation:

If the condition in a 'while' loop never becomes false, the loop will continue to execute indefinitely, resulting in an infinite loop.

## 7. What will the following C code snippet print?

``````int i = 0;
while (i < 3) {
printf("%d", i);
i++;
}``````
a) 012
b) 123
c) 0123
d) An infinite number of 0s

a) 012

### Explanation:

The loop prints the values of 'i' from 0 to 2 and then exits when 'i' becomes 3, resulting in the output "012".

## 8. Which of the following is a valid 'do...while' loop in C?

a) do { statements; } while condition;
b) do { statements; } while (condition)
c) do (condition) { statements; } while;
d) do { statements; } while (condition);

d) do { statements; } while (condition);

### Explanation:

A valid 'do...while' loop in C must end with a semicolon after the condition enclosed in parentheses.

## 9. How can you exit a 'while' loop prematurely in C?

a) Using the 'stop' statement
b) Using the 'exit' statement
c) Using the 'break' statement
d) By setting the condition to false

c) Using the 'break' statement

### Explanation:

The 'break' statement is used to exit a loop prematurely, immediately stopping the loop and moving to the next statement after the loop.

## 10. What is the role of the 'continue' statement in a 'while' loop in C?

a) To exit the loop
b) To skip the current iteration and proceed to the next iteration
c) To pause the loop temporarily
d) To restart the loop from the beginning

b) To skip the current iteration and proceed to the next iteration

### Explanation:

The 'continue' statement skips the remaining statements in the current loop iteration and proceeds with the next iteration of the loop.

## 11. What is the minimum number of times a 'do...while' loop is guaranteed to execute?

a) 0 times
b) 1 time
c) 2 times
d) Depends on the condition

b) 1 time

### Explanation:

A 'do...while' loop is guaranteed to execute at least once, regardless of the condition, as the condition is checked after the first execution.

## 12. Which of the following is an infinite loop in C?

a) while (1) { }
b) while (0) { }
c) do { } while (0);
d) for (;;) { }

a) while (1) { }

### Explanation:

'while (1)' creates an infinite loop because the condition '1' (which is always true) never becomes false.

## 13. What happens if the condition in a 'while' loop is always true?

a) The loop executes a fixed number of times
b) The loop executes only once
c) The loop executes indefinitely
d) The program terminates

c) The loop executes indefinitely

### Explanation:

If the condition in a 'while' loop is always true, the loop will continue to execute indefinitely, creating an infinite loop.

## 14. Can a 'while' loop be used to iterate over an array in C?

a) Yes, using an index variable
b) No, 'while' loops cannot be used with arrays
c) Only if the array has a known fixed size
d) Only in combination with a 'for' loop

a) Yes, using an index variable

### Explanation:

A 'while' loop can iterate over an array by using an index variable to access each element in turn.

## 15. In a 'do...while' loop, where should the increment/decrement statement typically be placed?

a) Before the loop body
b) At the beginning of the loop body
c) At the end of the loop body
d) After the loop condition