#include <stdio.h>
#include <stdlib.h>

int string_length(char * my_string);


char * reverse_string(char * my_string)
{
  int length = string_length(my_string);
  char * result = (char *) malloc(sizeof(char) * (length + 1));

  int i;
  for (i = 0; i < length; i++)
  {
    int j = length - i - 1;
    result[i] = my_string[j];
  }

  result[length] = 0;
  return result;
}


int string_length(char * my_string)
{
  int counter = 0;
  while(1)
  {
    if (my_string[counter] != 0)
    {
      counter++;
    }
    else
    {
      break;
    }
  }

  return counter;
}


int main()
{
  char * input = (char *) malloc(sizeof(char) * 1000);
  printf("enter a string:\n");
  scanf("%s", input); 

  char * reverse = reverse_string(input);
  printf("input = %s\n", input);
  printf("reverse = %s\n", reverse);

  free(input);
  free(reverse);
}