C Program to print a string in reverse using a pointer

#include <stdio.h>
int main()
{
    char str1[50];
    char revstr[50];
    char *stptr = str1;
    char *rvptr = revstr;
    int i=-1;
 		
    printf(" Input a string : ");
    scanf("%s",str1);
    while(*stptr)
    {
     stptr++;
     i++;
    }
    while(i>=0)
    {
     stptr--;
     *rvptr = *stptr;
     rvptr++;
     --i;
    }
    *rvptr='\0';
    printf(" Reverse of the string is : %s\n\n",revstr);
    return 0;
}