C Program to Read integers into an array and Reversing them using Pointers

Write a C program using pointers to read in an array of integers and print its elements in reverse order.

#include<stdio.h>
#include<conio.h>
#define MAX 30

void main()
{
int size,i,arr[MAX];
int *ptr;
clrscr();

ptr=&arr[0];

printf("Enter the size of array : ");
scanf("%d",&size);

printf("nEnter %d integers into array:n",size);
   for(i=0;i<size;i++)
   {
   scanf("%d",ptr);
   ptr++;
   }

ptr=&arr[size-1];

printf("nElements of array in reverse order are:n");

 for(i=size-1;i>=0;i--)
   {
   printf("nElement%d is %d :",i,*ptr);
   ptr--;
   }

getch();
}

Output :

Enter the size of array : 5
Enter 5 integers into array : 11 22 33 44 55
Elements of array in reverse order are :
Element 4 is : 55
Element 4 is : 44
Element 4 is : 33
Element 4 is : 22
Element 4 is : 11

Program to read integers into an array and reversing them using pointers Explanation :

1. We have declared one pointer variable and one array.

int size,i,arr[MAX];
int *ptr;

2. Address of first element of array is stored inside pointer variable.

ptr=&arr[0];

3. Accept Size of an Array.

printf("Enter the size of array : ");
scanf("%d",&size);

4. Now we have accepted element one by one using for loop and scanf statement .

printf("nEnter %d integers into array:n",size);
   for(i=0;i<size;i++)
   {
   scanf("%d",ptr);
   ptr++;
   }

5. Increment pointer variable so that it will then point to next element of array.
6. After accepting all elements store address of last element inside pointer variable.

ptr=&arr[size-1];

7. Again using reverse for loop and printf statement print an array.

for(i=size-1;i>=0;i--)
   {
   printf("nElement%d is %d :",i,*ptr);
   ptr--;
   }