C Programming Questions and Answers on Register Variables for Freshers

1. What is the output of this C code?

1.     #include 

2.     int main()

3.     {

4.         register int i = 10;

5.         int *p = &i;

6.         *p = 11;

7.         printf("%d %d\n", i, *p);

8.     }

a) Depends on whether i is actually stored in machine register
b) 10 10
c) 11 11
d) Compile time error

Answer: d

2. register keyword mandates compiler to place it in machine register.

a) true
b) false
c) Depends on the standard
d) None of the mentioned

Answer: b

3. What is the output of this C code?

1.     #include 

2.     int main()

3.     {

4.         register static int i = 10;

5.         i = 11;

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

7.     }

a) 10
b) Compile time error
c) Undefined behaviour
d) 11

Answer: b

4. What is the output of this C code?

1.     #include 

2.     int main()

3.     {

4.         register auto int i = 10;

5.         i = 11;

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

7.     }

a) 10
b) Compile time error
c) Undefined behaviour
d) 11

Answer: b

5. What is the output of this C code?

1.     #include 

2.     int main()

3.     {

4.         register const int i = 10;

5.         i = 11;

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

7.     }

a) 10
b) Compile time error
c) Undefined behaviour
d) 11

Answer: b

6. Register storage class can be specified to global variables

a) true
b) false
c) Depends on the compiler
d) Depends on the standard

Answer: b

7. Which among the following is wrong for “register int a;” ?

a) Compiler generally ignores the request.
b) You cannot take the address of this variable
c) Access time to a is critical
d) None of the mentioned

Answer: d

8. What is the output of this C code?

1.     #include 

2.     void main()

3.     {

4.         register int x = 5;

5.         m();

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

7.     }

8.     void m()

9.     {

10.         x++;

11.     }

a) 6
b) 5
c) Junk value
d) Compile time error

Answer: d

9. When compiler accepts the request to use the variable as a register?

a) It is stored in CPU
b) It is stored in cache memory
c) It is stored in main memory
d) It is stored in secondary memory

Answer: a

10. Which data type can be stored in register?

a) int
b) long
c) float
d) all of the mentioned

Answer: d

11. Which of the following operation is not possible in a register variable?

a) Reading the value into a register variable
b) Copy the value from a memory variable
c) Global declaration of register variable
d) All of the mentioned

Answer: d

12. Which among the following is the correct syntax to declare a static variable register?

a) static register a;
b) register static a;
c) Both static register a; and register static a;
d) We cannot use static and register together

Answer: d

13. Register variables reside in

a) stack
b) registers
c) heap
d) main memory

Answer: b

14. What is the output of this C code?

1.     #include 

2.     void main()

3.     {

4.         register int x = 0;

5.         if (x < 2)

6.         {

7.             x++;

8.             main();

9.         }

10.     }

a) Segmentation fault
b) main is called twice
c) main is called once
d) main is called thrice

Answer: a

15. What is the output of this C code?

1.     #include 

2.     void main()

3.     {

4.         register int x;

5.         printf("%d", x);

6.     }

a) 0
b) Junk value
c) Compile time error
d) Noting

Answer: b

16. What is the output of this C code?

1.     #include 

2.     register int x;

3.     void main()

4.     {

5.         printf("%d", x);

6.     }

a) Varies
b) 0
c) Junk value
d) Compile time error

Answer: d