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- Question
What will be the output of the program?
#include<stdio.h> #define FUN(i, j) i##j int main() { int va1=10; int va12=20; printf("%d\n", FUN(va1, 2)); return 0; }
Options- A. 10
- B. 20
- C. 1020
- D. 12
- Correct Answer
- 20
ExplanationThe following program will make you understand about ## (macro concatenation) operator clearly.#include<stdio.h> #define FUN(i, j) i##j int main() { int First = 10; int Second = 20; char FirstSecond[] = "CuriousTab"; printf("%s\n", FUN(First, Second) ); return 0; } Output: ------- CuriousTabThe preprocessor will replace FUN(First, Second) as FirstSecond.
Therefore, the printf("%s\n", FUN(First, Second) ); statement will become as printf("%s\n", FirstSecond );
Hence it prints CuriousTab as output.
Like the same, the line printf("%d\n", FUN(va1, 2)); given in the above question will become as printf("%d\n", va12 );.
Therefore, it prints 20 as output.
More questions
- 1. Bitwise & can be used to check if more than one bit in a number is on.
Options- A. True
- B. False Discuss
Correct Answer: True
- 2. The preprocessor can trap simple errors like missing declarations, nested comments or mismatch of braces.
Options- A. True
- B. False Discuss
Correct Answer: False
Explanation:
False, the preprocessor cannot trap the errors, it only replaces the macro with the given expression. But the compiler will detect errors.- 3. It is necessary that a header files should have a .h extension?
Options- A. Yes
- B. No Discuss
Correct Answer: No
Explanation:
No, the header files have any kind of extension.- 4. Bitwise | can be used to set multiple bits in number.
Options- A. Yes
- B. No Discuss
Correct Answer: Yes
- 5. Bitwise & can be used to check if a bit in number is set or not.
Options- A. True
- B. False Discuss
Correct Answer: True
- 6. A pointer union CANNOT be created
Options- A. Yes
- B. No Discuss
Correct Answer: No
- 7. What will be the output of the program?
#include<stdio.h> #include<stdlib.h> int main() { union test { int i; float f; char c; }; union test *t; t = (union test *)malloc(sizeof(union test)); t->f = 10.10f; printf("%f", t->f); return 0; }
Options- A. 10
- B. Garbage value
- C. 10.100000
- D. Error Discuss
Correct Answer: 10.100000
- 8. What will be the output of the program?
#include<stdio.h> int main() { int x=4, y, z; y = --x; z = x--; printf("%d, %d, %d\n", x, y, z); return 0; }
Options- A. 4, 3, 3
- B. 4, 3, 2
- C. 3, 3, 2
- D. 2, 3, 3 Discuss
Correct Answer: 2, 3, 3
Explanation:
Step 1: int x=4, y, z; here variable x, y, z are declared as an integer type and variable x is initialized to 4.
Step 2: y = --x; becomes y = 3; because (--x) is pre-decrement operator.
Step 3: z = x--; becomes z = 3;. In the next step variable x becomes 2, because (x--) is post-decrement operator.
Step 4: printf("%d, %d, %d\n", x, y, z); Hence it prints "2, 3, 3".
- 9. Functions cannot return a floating point number
Options- A. Yes
- B. No Discuss
Correct Answer: No
Explanation:
A function can return floating point value.Example:
#include <stdio.h> float sub(float, float); /* Function prototype */ int main() { float a = 4.5, b = 3.2, c; c = sub(a, b); printf("c = %f\n", c); return 0; } float sub(float a, float b) { return (a - b); }Output:
c = 1.300000- 10. What will be the output of the program?
#include<stdio.h> int main() { int a=100, b=200, c; c = (a == 100 || b > 200); printf("c=%d\n", c); return 0; }
Options- A. c=100
- B. c=200
- C. c=1
- D. c=300 Discuss
Correct Answer: c=1
Explanation:
Step 1: int a=100, b=200, c;
Step 2: c = (a == 100 || b > 200);
becomes c = (100 == 100 || 200 > 200);
becomes c = (TRUE || FALSE);
becomes c = (TRUE);(ie. c = 1)
Step 3: printf("c=%d\n", c); It prints the value of variable i=1
Hence the output of the program is '1'(one).
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