#include <iostream>
using namespace std;

void reverse_r(char* s, int a, int b) {
  if (a < b) {
    char tmp = s[a];
    s[a] = s[b];
    s[b] = tmp;
    reverse_r(s, a+1, b-1);
  }
}

void reverse(char s[]) {
  int a = 0;
  int b = strlen(s) - 1;
  reverse_r(s, a, b);
}

int main(int argc, char *argv[])
{
  char myname[] = "karab";

  cout << "Before: " << myname << endl;
  reverse(myname);
  cout << "After: " << myname << endl;

  return 0;
}