While Loop MCQ in C

While loop in C is a pre-test loop where the expression is evaluated then only statements are executed. It uses a test expression to control the loop. Before every iteration of the loop, the test expression is evaluated.

• While loop in C
• Do-while loop in C
• While vs do-while
• For loop in C

Q1) Choose the correct syntax of the while loop in C?

a)

while()
{
    if(condition)
    {
        //statement(s)
    }
}

b)

while(condition);
{
    //statement(s)
}

c)

while(condition)
{
    //statement(s);
}

d)

{
    //statements
}while(condition)

View Answer

Answer:- c)

while(condition)
{
//statement(s);
}

Q2) What is the output of the given below program?

#include<stdio.h>
int main()
{
  int i=1;
  while(1)
  {
    printf("N");
    i++;
    if(i==5) break;
  }
  return 0;
}

a) N
b) NNNN
c) NNNNN
d) Compile-time error

View Answer

Answer:- b) NNNN

Since the condition contains “1” it means the condition will always be true. But inside the while loop, if statements check the value of “i”. When the value of “i” becomes 5, the “break” statement loop will be terminated.

Q3) Find the output of the given program?

#include<stdio.h>
int main()
{
  int i = 0;
  while(0)
  {
    printf("N");
    i++;
    if(i==5) break;
  }
  return 0;
}

a) NNNN
b) NNNNN
c) Compiled Successfully, No Output
d) Compile-time error

View Answer

Answer:- c) Compiled Successfully, No Output

The condition of the while loop is “0” which means false. Therefore statements inside while loop never got a chance to execute.

Q4) What is the output of the given below program?

#include<stdio.h>
int main()
{
  while(1)
  {
    printf("N");
    i++;
    if(i==3) break;
  }
  return 0;
}

a) N
b) NN
c) NNN
d) Compiled Successfully, No Output
e) Compile-time error

View Answer

Answer:- e) Compile-time error

The variable “i” is not declared before it’s used.

Q5) What is the output of the given below program?

#include<stdio.h>
int main()
{
  while(true)
  {
    printf("Know Program");
    break;
  }
  return 0;
}

a) Know Program
b) Compiled Successfully, No Output
c) Know Program is printed an infinite number of times.
d) Compile-time error

View Answer

Answer:- d) Compile-time error

Here, “true” is an identifier, and it is not declared before it’s used.

Q6) Find the output of the given program?

#include<stdio.h>
int main()
{
  int a = 3;
  while(a == 3)
  {
    printf("Know Program");
    break;
  }
  return 0;
}

a) Know Program
b) Compiled Successfully, No Output
c) Know Program is printed infinite times.
d) Compile-time error

View Answer

Answer:- a) Know Program

The value of “a” is 3 therefore the condition becomes true. On the first iteration, the “break” statement was executed which terminated the loop.

Q7) What is the output of the given below program?

#include<stdio.h>
int main()
{
  int a = 3;
  while(a = 5)
  {
    printf("Hello ");
    break;
  }
  printf("Know Program ");
  return 0;
}

a) Hello
b) Know Program
c) Hello Know Program
d) Compile-time error

View Answer

Answer:- c) Hello Know Program

In the while condition, the value of a is assigned to 5 therefore condition will be always true. But in while block, “break” statement is called therefore on first iteration itself loop execution is completed. The remaining lines of code after the while loop will be executed.

Q8) Find the output of the given program?

#include<stdio.h>
int main()
{
  int a = 3;
  while(a >= 5)
  {
    printf("Hello ");
    break;
  }
  printf("Know Program ");
  return 0;
}

a) Hello
b) Know Program
c) Hello Know Program
d) Compile-time error

View Answer

Answer:- b) Know Program

The while loop condition a >= 5, 3 >= 5 becomes false. Therefore while loop never got a chance to execute. But remaining lines of code after the while loop will be executed.

Q9) Find the output of the given program?

#include<stdio.h>
int main()
{
  int a = 5;
  while(a <= 9)
  {
    printf("%d", a);
    a++;
  }
  return 0;
}

a) 5
b) 5678
c) 56789
d) Compile-time error

View Answer

Answer:- c) 56789

Q10) What is the output of the given below program?

#include<stdio.h>
int main()
{
  int a = 5;
  while(a <= 9)
  {
    printf("%d", a);
    a++;
    break;
  }
  return 0;
}

a) 5
b) 5678
c) 56789
d) Compile-time error

View Answer

Answer:- a) 5

Q11) Find the output of the given program?

#include<stdio.h>
int main()
{
  int a = 0;
  while(++a)
  {
    printf("Know Program ");
  }
  return 0;
}

a) Know Program
b) Compiled Successfully, No Output
c) Know Program is printed infinite times.
d) Compile-time error

View Answer

Answer:- c) Know Program is printed infinite times.

Due to condition “++a”, the value of a will be always incremented by 1 and it will be always > 0. Hence it becomes an infinite loop.

Q12) Find the output of the given program?

#include<stdio.h>
int main()
{
  int a = 0;
  while(a)
  {
    printf("Know Program ");
    a++;
  }
  return 0;
}

a) Know Program
b) Compiled Successfully, No Output
c) Know Program is printed infinite times.
d) Compile-time error

View Answer

Answer:- b) Compiled Successfully, No Output

Since the condition of “a” is 0 which represents false. Hence while loop will never get a chance to execute.

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