#include <stdio.h>

#include <conio.h>

#include <string.h>

void main()

{

char *str;

int i,len;

//not using any temp variable and assume we can use only string array and length

printf("Enter String : ");

scanf("%s",str);

len=strlen(str)-1;

for(i=0;i<strlen(str)/2;i++)

{

str[i]+=str[len];

str[len]=str[i]-str[len];

str[i]=str[i]-str[len--];

}

printf("Reverse String is : %s",str);

getch();

}