Pointer(C Program ) Questions and answers for exam Preparation

Question 1. Determine Output:
void main()
{
char far *farther, *farthest;
printf("%d..%d", sizeof(farther), sizeof(farthest));
}

4..2
2..2
4..4
2..4

Explanation:-

Answer: Option A. -> 4..2
The second pointer is of char type and not a far pointer.

Question 2. Determine Output:
main()
{
char *str1 = "abcd";
char str2[] = "abcd";
printf("%d %d %d", sizeof(str1), sizeof(str2), sizeof("abcd"));
}

2 5 5
2 4 4
8 5 5
2 4 5

Explanation:-

Answer: Option C. -> 8 5 5
In first sizeof, str1 is a character pointer so it gives you the size of the pointer variable. In second sizeof the name str2 indicates the name of the array whose size is 5 (including the 'null' termination character). The third sizeof is similar to the second one.

Question 3. Choose the best answer.
Prior to using a pointer variable

It should be declared.
It should be initialized.
It should be both declared and initialized.
None of these.

Explanation:-

Answer: Option C. -> It should be both declared and initialized.
Using a pointer variable, without initializing it, will be disastrous, as it will have a garbage value.

Question 4. Comment on the following pointer declaration?
int *ptr, p;

ptr is a pointer to integer, p is not.
ptr and p, both are pointers to integer.
ptr is pointer to integer, p may or may not be.
ptr and p both are not pointers to integer.

Explanation:-

Answer: Option A. -> ptr is a pointer to integer, p is not.

Question 5. What will be the output?
main()
{
char *p;
p = "Hello";
printf("%cn",*&*p);
}

Hello
H
Some address will be printed
None of these.

Explanation:-

Answer: Option B. -> H
* is a dereference operator & is a reference operator. They can be applied any number of times provided it is meaningful. Here p points to the first character in the string "Hello". *p dereferences it and so its value is H. Again & references it to an address and * dereferences it to the value H.

Question 6. What will be printed after compiling and running the following code?
main()
{
char *p;
printf("%d %d",sizeof(*p), sizeof(p));
}

1 1
1 2
2 1
2 2

Explanation:-

Answer: Option B. -> 1 2
The sizeof() operator gives the number of bytes taken by its operand. p is a character pointer, which needs one byte for storing its value (a character). Hence sizeof(*p) gives a value of 1. Since it needs two bytes to store the address of the character pointer sizeof(p) gives 2.

Question 7. Find the output of the following program.
void main()
{
char *msg = "hi";
printf(msg);
}

Explanation:-

Answer: Option A. -> hi

Question 8. Find the output of the following program.
void main()
{
int array[10];
int *i = &array[2], *j = &array[5];
int diff = j-i;
printf("%d", diff);
}

3
6
Garbage value
Error

Explanation:-

Answer: Option A. -> 3
When subtracting pointers you get the number of elements between those addresses, not the number of bytes.

Question 9. Which of the following is the correct way of declaring a float pointer:

float ptr;
float *ptr;
*float ptr;
None of the above

Explanation:-

Answer: Option B. -> float *ptr;

Question 10. What will be the output of the following program code?
#include
void main()
{
int i=3, *j, **k;
j = &i;
k = &j;
printf("%d%d%d", *j, **k, *(*k));
}

Explanation:-

Answer: Option C. -> 333