Quiz on Relational and Logical Operator in C

Quiz on Relational and Logical operator in C | Relational operators are used to check given condition or expression is true or false. The Combination of some operands and constants with relational operators is called a relational expression.

If the relation is true then the value of the relational expression is 1 and if the relation is false then the value of the expression is 0. In C language (with relational operator), every non-zero value is 1 i.e. true.

C language supports three logical operators:- AND (&&), OR(||) and NOT(!). An expression which combines two or more relational expressions is termed as logical expression. Like the simple relational expressions, a logical expression also yields a value of true (1) or false(0).

Recommended Reading:- Operators in C

Relational and Logical operator Quiz in C

Find the output of the programs given in Quiz on Relational and Logical operator in C?

Q1) Find the output of the given C program.

#include<stdio.h>
int main()
{
  int x, y, z;
  x = 9 > 8 > 7;
  y = 9 > 8 > 0;
  z = 9 > 8 > 1;
  printf("%d %d %d", x, y, z);
  return 0;
}

a) 0 0 1
b) 0 1 0
c) 1 0 0
d) 0 1 1


Ans:- b) 0 1 0

For >, execution starts from left to right. In statement x = 9>8>7; first 9>8 will be evaluated and the result is 1. Now, x = 1>7; so, result will be 0. Similarly, y and z will be calculated.


Q2) Find the output of the given C program.

#include<stdio.h>
int main()
{
  int a=-1, b=1, c, d;
  c = !a && b;
  d = !a || b;
  printf("%d %d %d %d",a,b,c,d);
  return 0;
}

a) -1 1 1 0
b) -1 1 0 0
c) -1 1 1 1
d) -1 1 0 1


Ans:- d) -1 1 0 1


Q3) Find the output of the given C program.

#include<stdio.h>
int main()
{
  printf("%d ",5>2 && 1<2);
  printf("%d ", 4>5 || 2<1);
  printf("%d ",!(2>3));
  return 0;
}

a) 0 1 0
b) 0 1 1
c) 1 0 0
d) 1 0 1


Ans:- d) 1 0 1


Q4) Find the output of the given C program.

#include<stdio.h>
int main()
{
  int a;
  a = 'a' > 'A';
  printf("%d",a);
  return 0;
}

a) Garbage Value
b) 0
c) 1


Ans:- c) 1

The decimal value of ‘a’ and ‘A’ is 97 and 65 respectively. 97 > 65 gives true(1).


Q5) Find the output of the given C program.

#include<stdio.h>
int main()
{
  int x=0, y=0;
  printf("%d ", x++ && ++y);
  printf("%d %d\t",x,y);
  
  x = 0, y=1;
  printf("%d ", ++x || ++y);
  printf("%d %d",x,y);
  return 0;
}

a) 0 1 0 1 1 2
b) 0 1 1 1 1 1
c) 0 1 0 1 1 1
d) 0 1 1 1 1 2


Ans:- c) 0 1 0 1 1 1

For logical AND (&&) operator, if the left operand yields a false (0) value, then the compiler does not evaluate the right operand and directly gives result false (0). For logical OR ( || ) operator, if the left operand yields a true (1) value, then the compiler does not evaluate the right operand and directly gives result 1 (true).


Q6) Find the output of the given C program.

#include<stdio.h>
int main()
{
  printf("%d ", -9 && 9);
  printf("%d", -9 || 9);
  return 0;
}

a) 0 0
b) 0 1
c) 1 1
d) 1 0


Ans:- c) 1 1

In C non-zero value treated as true (1). So, we can write -9 && 9 as 1 && 1, which yeilds 1. Similarly, 1 || 1 produces 1.


Q7) Find the output of the given C program.

#include< stdio.h>
int main()
{
  int x, y, z;
  x = 9;
  y = 10;
  z = x == y;
  printf("%d", z);
  return 0;
}

a) None of these
b) Garbage Value
c) 0
d) 1


Ans:- c) 0

9 is not equal to 10.


Q8) Find the output of the given C program.

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

a) 1
b) Garbage Value
c) 0


Ans:- c) 0

Any non-zero value can be treated as true so, !(true) && true can be wriiten as false && ture, which produces false(0).


Q9) Find the output of the given C program.

#include<stdio.h>
int main()
{
  int i=10;
  i= !i > 14;
  printf("%d",i);
  return 0;
}

a) 0
b) 1
c) Garbage Value


Ans:- a) 0

Comparison of constant ‘14’ with boolean expression is always false.


Q10) Find the output of the given C program.

#include<stdio.h>
int main()
{
  int x= 90;
  printf("%d %d %d", x>50, x=5, x>10);
  return 0;
}

a) 0 0 0
b) 0 1 1
c) 0 5 1
d) 0 18 1


Ans:- c) 0 5 1

The expression is evaluated from right to left. First, expression x>10 will be calculated. 90>10 so the result is 1. Now, x=5 is an assignment expression, not a relational expression. Here the value of 5 will print by printf() and the value of x updated to 5. Third expression x> 10 gives 0 or false because 5<10.


Q11) Find the output of the given C program.

#include<stdio.h>
int main()
{
  int a;
  a = !8;
  printf("%d",a);
  return 0;
}

a) Garbage Value
b) 0
c) 1


Ans:- b) 0

Any non-zero value can be treated as true so, !(true) gives false(0).


Q12) Find the output of the given C program.

#include<stdio.h>
int main()
{
  int a,b,c;
  a = b = 10;
  c = a == b;
  printf("%d %d %d",a,b,c);
  return 0;
}

a) 10 10 10
b) 10 10 1
c) 1 1 1
d) 10 10 0


Ans:- a) 10 10 10

a=b=10 so, value of a and b becomes 10. c= a==b; 10==10 gives 1, so value of c becomes 1.


Q13) Find the output of the given C program.

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

a) 1 0
b) 0 5
c) 1 5
d) 0 0


Ans:- a) 1 0

a==b gives 0 because 9 is not equal to 5. a=b gives 5 because the value of b is 5.


Q14) Find the output of the given C program.

#include<stdio.h>
int main()
{
  int x=55, y=20, a;
  a = (x == 55 || y>20);
  printf("%d ", a);
  return 0;
}

a) 1
b) Garbage Value
c) 0


Ans:- a) 1

x==55 gives 1 because 55 is equal to 55. We are working with logical OR (||) operator and its left operand gives 1 so, final result 1 will stored in variable a.

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