Quiz on Increment and Decrement Operators in C

Quiz on Increment and Decrement Operators in C | Increment and decrement operators are also known as unary operators’ because they operate on a single operand. The increment operator (++) adds 1 to its operand and decrement operator (--) subtracts one.

OperatorMeaning
++Increment Operator
– –Decrement Operator

Syntax:-
++variable; // pre-increment operator
variable++; //post-increment operator
--variable; // pre-decrement operator
variable--; //post-decrement operator

Recommended Reading:- Operators in C

C Quiz on Increment and Decrement

Q1) What will be the output of below C program?

#include<stdio.h>
int main()
{
  int x, y;
  x = 5;
  y = x++ / 2;
  printf("%d", y);
  return 0;
}

a) 3
b) Compile-time error
c) None of these
d) 2


Ans:- d) 2

The given expression is:- y=x++ / 2; x++ so post-increment, y=5/2=2. Hence, x=6 and y=2.


Q2) What will be the output of below C program?

#include<stdio.h>
int main()
{
  int a=4,b,c;
  b = --a;
  c = a--;
  printf("%d %d %d",a,b,c);
  return 0;
}

a) 3 3 2
b) 2 3 2
c) 3 2 2
d) 2 3 3


Ans:- d) 2 3 3

The first expression is b=–a; so, a becomes 3 (a=3) and b=3. Now, c=a–; so, c=3 and a=2. Finally, a=2, b=3 and c=3.


Q3) What will be the output of below C program?

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

a) 6
b) 5
c) Compile-time error
d) 7


Ans:- c) Compile-time error

Compile time error: lvalue required as increment operand


Q4) What will be the output of below C program?

#include<stdio.h>
int main()
{
  int a=3, b=9;
  printf("%d ", ++(a*b+1));
  return 0;
}

a) Compile-time error
b) 29
c) 28
d) None of these


Ans:- a) Compile-time error

Error: lvalue required as increment operand; The operand of increment and decrement operators must be a variable, not a constant or expression.


Q5) What will be the output of below C program?

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

a) 21 10 10
b) Compile-time error
c) 21 10 11
d) 21 11 11


Ans:- b) Compile-time error

Compile time error: lvalue required as increment operand
c=a+++++b;
^~


Q6) What will be the output of below C program?

#include<stdio.h>
int main()
{
  int a=2,b=1,c=0;
  c = a +++ b;
  printf("%d %d %d",a,b,c);
  return 0;
}

a) 3 1 3
b) Compile-time error
c) 2 2 4
d) None of these


Ans:- a) 3 1 3

The expression c=a+++b; is treated as c=(a++)+b; so, a=3, b=1, c=3


Q7) What will be the output of below C program?

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

a) 5 4 4
b) 5 5 4
c) 5 4 3
d) 5 5 5


Ans:- b) 5 5 4


Q8) What will be the output of below C program?

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

a) Compile-time error
b) 10
c) 12
d) 11


Ans:- a) Compile-time error

Compile time error: lvalue required as increment operand
b=++++a;
^~


Q9) What will be the output of below C program?

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

a) 9 -9 -9 9
b) 10 9 9 9
c) 10 -9 -9 8
d) 10 9 9 8


Ans:- a) 9 -9 -9 9

These are not increment or decrement operators.


Q10) What will be the output of below C program?

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

a) 5 5
b) 6 6
c) 6 5
d) 5 6


Ans:- c) 6 5

x=5 and y=x++; from y=x++, it is postfix increment so first value of x copies to variable y and now the value of x incremented by 1. Hence y=5 and x=6.

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