Question

1. Declare two int: x and y

Declare two pointers p and q capable of pointing to int

Make p point to y

Make q point to x

Assign 3 and 6 to x and y without mentioning x and y

Redirect p to point to the same location q points to (two ways)

Make q point to y

Swap the values of x and y without mentioning x and y

2. Declare two int: x and y

Declare two pointers p and q capable of pointing to int

Make p point to x

Make q point to y

Assign 3 to x and the same value plus one to y without mentioning y

Swap p and q

Make q point to y

Swap the values of p and q point to.

3, Declare three int: x,y and z

Declare two pointers p,q and r capable of pointing to int

Make p point to y.

Make q point to x.

Make r point to z.

Assign 5, 10 and 20 to x, y and z respectively without mentioning x ,y and z

Swap the values of x,y and z without mentioning x , y and z in the following way: x gets the value of z, y gets the previous value of x and z gets the previous value of y.

4. Dynamically allocate memory for two integers.

Swap their values.

5. Please, write a loop to print an array a with pointers. You can use a variable “size” for array size

6. write a loop to print an array a with pointers backwards. You can use a variable “size” for array size.

Please write the code in C

Answer 1

1.

Code:

#include<stdio.h>
int main()
{
   int x,y,*p,*q,temp;
   /*Declaring the variables*/
   p=&y;/*p points to y*/
   q=&x;/*q points to x*/
   *p=6;/*y=6*/
   *q=3;/*x=3*/
   temp=p;
   p=q;
   q=temp;
   /*changing the pointers*/
   printf("*p=%d\n",*p);
   printf("*q=%d",*q);
   /*Printing the poiters*/
  
}

Output:

2.

Code:

#include<stdio.h>
int main()
{
   int x,y,*p,*q,temp;
   /*Declaring the variables*/
   p=&x;/*p points to x*/
   q=&y;/*q points to y*/
   *p=3;/*x=3*/
   *q=*p+1;/*y=x+1*/
   temp=p;
   p=q;
   q=temp;
   /*interchanging the pointer references*/
   printf("*p=%d\n",*p);
   printf("*q=%d",*q);
   /*Printintg the values*/      
}

Output:

3.

Code:

#include<stdio.h>
int main()
{
   int x,y,z,*p,*q,*r,temp,temp1;/*Declarig the variables*/
   p=&y;/*p points to y*/
   q=&x;/*q points to x*/
   r=&z;/*r points to z*/
   *q=5;/*x=5*/
   *p=10;/*y=10*/
   *r=20;/*z=20*/
   temp=*q;
   *q=*r;/*x get the z value*/
   temp1=*p;
   *p=temp;/*y get the x previous value*/
   *r=temp1;/*z get the y value*/
   printf("x=%d\ny=%d\nz=%d",x,y,z);
   /*Printing x y z */  
}

Output:

4.

Code:

#include<stdio.h>
int main()
{
   int *a=(int*) malloc(sizeof(int));
   int *b=(int*) malloc(sizeof(int));
   /*Dynamically alocaing 2 integers*/
   int temp;
   *a=5;
   *b=10;
   /*assigning values*/
   temp=*a;
   *a=*b;
   *b=temp;
   /*swapping*/
   printf("*a=%d \n*b=%d",*a,*b);
   /*printing the *a and *b*/  
}

Output:

5.

Code:

#include<stdio.h>
main()
{
   int a[5]={1,2,3,4,5};
   int i,size=5;
   /*Declaring the vriables*/
   printf("Priting the array: ");
   for(i=0;i<size;i++)
   {
       printf("%d ",*(a+i));
       /*Printing the array*/
   }
   printf("\nPrinting elements in backword direction: ");
   for(i=size-1;i>=0;i--)
   {
       printf("%d ",*(a+i));
       /*printing in reverse order*/
   }
}

Output: