Multiple Choice Questions and Answers for Increment and Decrement Operators in C Language

Online C test focuses on “Increment and Decrement Operators”. One shall practice these test questions to improve their C programming skills needed for various interviews (campus interviews, walkin interviews, company interviews), placements, entrance exams and other competitive exams.

Here is a listing of online C test questions on “Increment and Decrement Operators” along with answers, explanations and/or solutions:

1. What is the difference between the following 2 codes?

1.     #include  //Program 1

2.     int main()

3.     {

4.         int d, a = 1, b = 2;

5.         d =  a++ + ++b;

6.         printf("%d %d %d", d, a, b);

7.     }

1.     #include  //Program 2

2.     int main()

3.     {

4.         int d, a = 1, b = 2;

5.         d =  a++ +++b;

6.         printf("%d %d %d", d, a, b);

7.     }

a) No difference as space doesn’t make any difference, values of a, b, d are same in both the case
b) Space does make a difference, values of a, b, d are different
c) Program 1 has syntax error, program 2 is not
d) Program 2 has syntax error, program 1 is not

Answer:d

2. What is the output of this C code?

1.     #include 

2.     int main()

3.     {

4.         int a = 1, b = 1, c;

5.         c = a++ + b;

6.         printf("%d, %d", a, b);

7.     }

a) a = 1, b = 1
b) a = 2, b = 1
c) a = 1, b = 2
d) a = 2, b = 2

Answer:b

3. What is the output of this C code?

1.     #include 

2.     int main()

3.     {

4.         int a = 1, b = 1, d = 1;

5.         printf("%d, %d, %d", ++a + ++a+a++, a++ + ++b, ++d + d++ + a++);

6.     }

a) 15, 4, 5
b) 9, 6, 9
c) 9, 3, 5
d) Undefined (Compiler Dependent)
View Answer

Answer:d

4. For which of the following, “PI++;” code will fail?
a) #define PI 3.14
b) char *PI = “A”;
c) float PI = 3.14;
d) None of the Mentioned

Answer:a

5. What is the output of this C code?

1.     #include 

2.     int main()

3.     {

4.         int a = 10, b = 10;

5.         if (a = 5)

6.         b--;

7.         printf("%d, %d", a, b--);

8.     }

a) a = 10, b = 9
b) a = 10, b = 8
c) a = 5, b = 9
d) a = 5, b = 8

Answer:c

6. What is the output of this C code?

1.     #include 

2.     int main()

3.     {

4.         int i = 0;

5.         int j = i++ + i;

6.         printf("%d\n", j);

7.     }

a) 0
b) 1
c) 2
d) Compile time error

Answer:a

7. What is the output of this C code?

1.     #include 

2.     int main()

3.     {

4.         int i = 2;

5.         int j = ++i + i;

6.         printf("%d\n", j);

7.     }

a) 6
b) 5
c) 4
d) Compile time error

Answer:a

8. Comment on the output of this C code?

1.     #include 

2.     int main()

3.     {

4.         int i = 2;

5.         int i = i++ + i;

6.         printf("%d\n", i);

7.     }

a) = operator is not a sequence point
b) ++ operator may return value with or without side effects
c) it can be evaluated as (i++)+i or i+(++i)
d) Both a and b

Answer:a

9. What is the output of this C code?

1.     #include 

2.     int main()

3.     {

4.         int i = 0;

5.         int x = i++, y = ++i;

6.         printf("%d % d\n", x, y);

7.         return 0;

8.     }

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

Answer:a 

10. What is the output of this C code?

1.     #include 

2.     int main()

3.     {

4.         int i = 10;

5.         int *p = &i;

6.         printf("%d\n", *p++);

7.     }

a) 10
b) 11
c) Garbage value
d) Address of i

Answer:a 

11. What is the output of this C code?

1.     #include 

2.     void main()

3.     {

4.         int x = 97;

5.         int y = sizeof(x++);

6.         printf("X is %d", x);

7.     }

a) X is 97
b) X is 98
c) X is 99
d) Run time error

Answer:a 

12. What is the output of this C code?

1.     #include 

2.     void main()

3.     {

4.         int x = 4, y, z;

5.         y = --x;

6.         z = x--;

7.         printf("%d%d%d", x,  y, z);

8.     }

a) 3 2 3
b) 2 3 3
c) 3 2 2
d) 2 3 4

Answer:b 

13. What is the output of this C code?

1.     #include 

2.     void main()

3.     {

4.         int x = 4;

5.         int *p = &x;

6.         int *k = p++;

7.         int r = p - k;

8.         printf("%d", r);

9.     }

a) 4
b) 8
c) 1
d) Run time error

Answer:c 

14. What is the output of this C code?

1.  #include 

2.     void main()

3.     {

4.         int a = 5, b = -7, c = 0, d;

5.         d = ++a && ++b || ++c;

6.         printf("\n%d%d%d%d", a,  b, c, d);

7.     }

a) 6 -6 0 0
b) 6 -5 0 1
c) -6 -6 0 1
d) 6 -6 0 1

Answer:d 

15. What is the output of this C code?

1.  #include 

2.     void main()

3.     {

4.         int a = -5;

5.         int k = (a++, ++a);

6.         printf("%d\n", k);

7.     }

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

Answer:d