Viva Questions on Loops with Model Answers
1. What is a loop in C programming? Why do we use it?
Answer:
A loop is a control structure in C that repeatedly executes a block of code until a specified condition is true. We use loops to avoid writing repetitive code and to perform iterative tasks efficiently.2. Explain the difference between while, do…while, and for loops in C.
Answer:
- while loop: Condition is checked first, then the body executes. (Entry-controlled loop)
- do…while loop: Body executes first, then condition is checked. (Exit-controlled loop, runs at least once)
- for loop: Used when initialization, condition, and increment/decrement are all in one line. Best for fixed iterations.
3. What happens if the loop condition is never satisfied in a while loop?
Answer:
If the condition is false at the beginning, the while loop body will never execute even once.
4. Can a for loop run infinitely? Give an example.
Answer:
Yes. If the loop condition is always true or missing, the loop runs infinitely.
Example:
for(;;) {
printf("Infinite loop\n");
}
5. What is the difference between break and continue statements inside loops?
Answer:
• break: Immediately exits the loop and transfers control outside.
• continue: Skips the current iteration and jumps to the next iteration of the loop.
6. What is an infinite loop? Write a simple example in C.
Answer:
An infinite loop is a loop that never terminates because the condition always remains true.
Example:
while(1) {
printf("Hello\n");
}
7. How is the initialization, condition, and increment part of a for loop optional? Give an example.
Answer:
All three parts in a for loop are optional. If omitted, they must be handled inside the loop body.
Example:
int i = 1;
for(; ; ) {
if(i > 5) break;
printf("%d ", i);
i++;
}
8. What is the output of the following code?
int i = 1;
while(i <= 5){
printf("%d ", i);
i++;
}
Answer:
Output:
1 2 3 4 5
9. Write a C program to print numbers from 1 to 10 using a do…while loop.
Answer:
#include <stdio.h>
int main() {
int i = 1;
do {
printf("%d ", i);
i++;
} while(i <= 10);
return 0;
}
10. Explain nested loops with an example (e.g., printing a multiplication table).
Answer:
A nested loop is a loop inside another loop.
Example-Multiplication table:
for(int i = 1; i <= 3; i++) {
for(int j = 1; j <= 3; j++) {
printf("%d ", i * j);
}
printf("\n");
}
Output:
1 2 3
2 4 6
3 6 9
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