Structures, Unions, Enums problems
- 1. A union cannot be nested in a structure
Options- A. True
- B. False Discuss
Correct Answer: False
- 2. Bit fields CANNOT be used in union.
Options- A. True
- B. False Discuss
Correct Answer: False
Explanation:
The following is the example program to explain "using bit fields inside an union".
#include<stdio.h>
union Point
{
unsigned int x:4;
unsigned int y:4;
int res;
};
int main()
{
union Point pt;
pt.x = 2;
pt.y = 3;
pt.res = pt.y;
printf("\n The value of res = %d" , pt.res);
return 0;
}
// Output: The value of res = 3
- 3. one of elements of a structure can be a pointer to the same structure.
Options- A. True
- B. False Discuss
Correct Answer: True
- 4. A structure can contain similar or dissimilar elements
Options- A. True
- B. False Discuss
Correct Answer: True
- 5. It is not possible to create an array of pointer to structures.
Options- A. True
- B. False Discuss
Correct Answer: False
- 6. If a char is 1 byte wide, an integer is 2 bytes wide and a long integer is 4 bytes wide then will the following structure always occupy 7 bytes?
struct ex { char ch; int i; long int a; };
Options- A. Yes
- B. No Discuss
Correct Answer: No
Explanation:
A compiler may leave holes in structures by padding the first char in the structure with another byte just to ensures that the integer that follows is stored at an location. Also, there might be 2extra bytes after the integer to ensure that the long integer is stored at an address, which is multiple of 4. Such alignment is done by machines to improve the efficiency of accessing values.
- 7. Can we have an array of bit fields?
Options- A. Yes
- B. No Discuss
Correct Answer: No
- 8. size of union is size of the longest element in the union
Options- A. Yes
- B. No Discuss
Correct Answer: Yes
- 9. Can a structure can point to itself?
Options- A. Yes
- B. No Discuss
Correct Answer: Yes
Explanation:
A structure pointing to itself is called self-referential structures.
- 10. If the following structure is written to a file using fwrite(), can fread() read it back successfully?
struct emp { char *n; int age; }; struct emp e={"CuriousTab", 15}; FILE *fp; fwrite(&e, sizeof(e), 1, fp);
Options- A. Yes
- B. No Discuss
Correct Answer: No
Explanation:
Since the structure contain a
char pointer while writing the structure to the disk using
fwrite() only the value stored in pointer
n will get written. so
fread() fails to read.
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