Output of following program? C #include <stdio.h> int main() { int *ptr; int x; ptr = &x; *ptr = 0; printf(" x = %d ", x); printf(" *ptr = %d ", *ptr); *ptr += 5; printf(" x = %d ", x); printf(" *ptr = %d ", *ptr); (*ptr)++; printf(" x = %d ", x); printf(" *ptr = %d ", *ptr); return 0; }

x = 0 *ptr = 0 x = 5 *ptr = 5 x = 6 *ptr = 6

x = garbage value *ptr = 0 x = garbage value *ptr = 5 x = garbage value *ptr = 6

x = 0 *ptr = 0 x = 5 *ptr = 5 x = garbage value *ptr = garbage value

x = 0 *ptr = 0 x = 0 *ptr = 0 x = 0 *ptr = 0

Consider a compiler where int takes 4 bytes, char takes 1 byte and pointer takes 4 bytes. C #include <stdio.h> int main() { int arri[] = {1, 2 ,3}; int *ptri = arri; char arrc[] = {1, 2 ,3}; char *ptrc = arrc; printf("sizeof arri[] = %d ", sizeof(arri)); printf("sizeof ptri = %d ", sizeof(ptri)); printf("sizeof arrc[] = %d ", sizeof(arrc)); printf("sizeof ptrc = %d ", sizeof(ptrc)); return 0; }

sizeof arri[] = 12 sizeof ptri = 4 sizeof arrc[] = 3 sizeof ptrc = 4

sizeof arri[] = 3 sizeof ptri = 4 sizeof arrc[] = 3 sizeof ptrc = 4

sizeof arri[] = 12 sizeof ptri = 4 sizeof arrc[] = 3 sizeof ptrc = 1

sizeof arri[] = 3 sizeof ptri = 4 sizeof arrc[] = 3 sizeof ptrc = 1

C #include<stdio.h> int main() { int arr[] = {10, 20, 30, 40, 50, 60}; int *ptr1 = arr; int *ptr2 = arr + 5; printf("Number of elements between two pointer are: %d.", (ptr2 - ptr1)); printf("Number of bytes between two pointers are: %d", (char*)ptr2 - (char*) ptr1); return 0; } Assume that an int variable takes 4 bytes and a char variable takes 1 byte

Number of elements between two pointer are: 5. Number of bytes between two pointers are: 20

Number of elements between two pointer are: 20. Number of bytes between two pointers are: 20

Number of elements between two pointer are: 5. Number of bytes between two pointers are: 5

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Question 1

What is the output of following program?

# include <stdio.h>
void fun(int x)
{
    x = 30;
}

int main()
{
  int y = 20;
  fun(y);
  printf("%d", y);
  return 0;
}

30
20
Compiler Error
Runtime Error

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Question 2

Output of following program?

# include <stdio.h>
void fun(int *ptr)
{
    *ptr = 30;
}

int main()
{
  int y = 20;
  fun(&y);
  printf("%d", y);

  return 0;
}

20
30
Compiler Error
Runtime Error

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Question 3

Output of following program?

#include <stdio.h>

int main()
{
    int *ptr;
    int x;

    ptr = &x;
    *ptr = 0;

    printf(" x = %d\\n", x);
    printf(" *ptr = %d\\n", *ptr);

    *ptr += 5;
    printf(" x  = %d\\n", x);
    printf(" *ptr = %d\\n", *ptr);

    (*ptr)++;
    printf(" x = %d\\n", x);
    printf(" *ptr = %d\\n", *ptr);

    return 0;
}

x = 0
*ptr = 0
x = 5
*ptr = 5
x = 6
*ptr = 6
x = garbage value
*ptr = 0
x = garbage value
*ptr = 5
x = garbage value
*ptr = 6
x = 0
*ptr = 0
x = 5
*ptr = 5
x = garbage value
*ptr = garbage value
x = 0
*ptr = 0
x = 0
*ptr = 0
x = 0
*ptr = 0

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Question 4

Consider a compiler where int takes 4 bytes, char takes 1 byte and pointer takes 4 bytes.

#include <stdio.h>

int main()
{
    int arri[] = {1, 2 ,3};
    int *ptri = arri;

    char arrc[] = {1, 2 ,3};
    char *ptrc = arrc;

    printf("sizeof arri[] = %d ", sizeof(arri));
    printf("sizeof ptri = %d ", sizeof(ptri));

    printf("sizeof arrc[] = %d ", sizeof(arrc));
    printf("sizeof ptrc = %d ", sizeof(ptrc));

    return 0;
}

sizeof arri[] = 3 sizeof ptri = 4 sizeof arrc[] = 3 sizeof ptrc = 4
sizeof arri[] = 12 sizeof ptri = 4 sizeof arrc[] = 3 sizeof ptrc = 1
sizeof arri[] = 3 sizeof ptri = 4 sizeof arrc[] = 3 sizeof ptrc = 1
sizeof arri[] = 12 sizeof ptri = 4 sizeof arrc[] = 3 sizeof ptrc = 4

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Question 5

Assume that float takes 4 bytes, predict the output of following program.

#include <stdio.h>

int main()
{
    float arr[5] = {12.5, 10.0, 13.5, 90.5, 0.5};
    float *ptr1 = &arr[0];
    float *ptr2 = ptr1 + 3;

    printf("%f ", *ptr2);
    printf("%d", ptr2 - ptr1);

   return 0;
}

90.500000 3
90.500000 12
10.000000 12
0.500000 3

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Question 6

#include<stdio.h>
int main()
{
    int arr[] = {10, 20, 30, 40, 50, 60};
    int *ptr1 = arr;
    int *ptr2 = arr + 5;
    printf("Number of elements between two pointer are: %d.", 
                                (ptr2 - ptr1));
    printf("Number of bytes between two pointers are: %d",  
                              (char*)ptr2 - (char*) ptr1);
    return 0;
}

Assume that an int variable takes 4 bytes and a char variable takes 1 byte

Number of elements between two pointer are: 5. Number of bytes between two pointers are: 20
Number of elements between two pointer are: 20. Number of bytes between two pointers are: 20
Number of elements between two pointer are: 5. Number of bytes between two pointers are: 5
Compiler Error
Runtime Error

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Question 7

#include<stdio.h> 
int main() 
{ 
   int a; 
   char *x; 
   x = (char *) &a; 
   a = 512; 
   x[0] = 1; 
   x[1] = 2; 
   printf("%d\\n",a);   
   return 0; 
}

What is the output of above program?

Machine dependent
513
258
Compiler Error

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Question 8

int main()
{
 char *ptr = "GeeksQuiz";
 printf("%c", *&*&*ptr);
 return 0;
}

Compiler Error
Garbage Value
Runtime Error
G

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Question 9

#include<stdio.h>
void fun(int arr[])
{
  int i;
  int arr_size = sizeof(arr)/sizeof(arr[0]);
  for (i = 0; i < arr_size; i++)
      printf("%d ", arr[i]);
}

int main()
{
  int i;
  int arr[4] = {10, 20 ,30, 40};
  fun(arr);
  return 0;
}

10 20 30 40
Machine Dependent
10 20
Northing

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Question 10

The reason for using pointers in a C program is

Pointers allow different functions to share and modify their local variables.
To pass large structures so that complete copy of the structure can be avoided.
Pointers enable complex “linked" data structures like linked lists and binary trees.
All of the above

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