int remove_duplicates(char *str)
{
   int char_check=0;
   int i,j;
   char ch;

   if(str == NULL)
     return 0;

   /* check from 1st character in the string */
   while(str[char_check]) {
      
      ch = str[char_check];
      
      i = j = char_check + 1;

      /* logic to remove the repeated character */
      while(str[i]) {
         if(str[i] != ch) {
             str[j] = str[i];
             j++; 
         }
         i++; 
      }
      str[j]='\0';

      char_check++;
   }
   printf("String after removing duplicates : %s\n",str);
   return 1;
}

#include <stdio.h>

main(int argc, char **argv)
{
  int i;
  char *source = argv[1];
  char *dest;
  char *temp;

  unsigned int bitmap[8] = {0,0,0,0,0,0,0,0};
  unsigned char c;
  unsigned int mask;

  dest = (char*)malloc(strlen(source));
  temp = dest;

  printf("before %s\n", source); 
  i=0;
  while(source[i])
  {
    c = source[i];
    mask = 1 << (c % 32);

    if ((bitmap[c/32] & mask) == 0) 
    {
      *temp++ = source[i];
      bitmap[c/32] |= mask;
    }
    i++;
  }

  *temp = '\0'; 
    
  printf("after %s\n", dest); 
}