Pointer At Fixed Location

Reverse the content of array using pointer at fixed location

In this program,pointer ptr is used to save the content.Although actual array is not used but it saves n values.The pointer is kept at fixed location and counter i is incremented to save the values.For reversing these values,two extreme memory addresses are considered i.e. i and j.The values are swapped using while loop.Temporay variable t is used for swapping the two adjacent values.The pointer ptr is at fixed location and the counter i and j increments and decrements respectively while swapping the values.When the while loop terminates,the content of array gets reversed.

#include < stdio.h >
#include < conio.h > 
#include < alloc.h>
void main()
{
	int num,rem[20],*ptr;
	clrscr();
	printf("\nEnter number:");
	scanf("%d",&num);
	ptr=rem;
	while(num!=0)
	{
		*ptr=num%16;
		num=num/16;
		ptr++;
	}
	ptr--;
	while(ptr>=rem)
	{
		if(*ptr < 10)
			printf("%d",*ptr);
		else
			printf("%c",*ptr+55);
			ptr--;
	}
}