void swap_recs(void *record1, void *record2)
{
  //printf("hi\n");
  //record1=malloc(sizeof(Record));
  //record2=malloc(sizeof(Record));
  Record temp;
  temp.id = * (int *)(record1+0);
  strcpy(temp.name, (char *)(record1+sizeof(int)) );
  strcpy(temp.surname, (char *)(record1+sizeof(int) + 15*sizeof(char)) );
  strcpy(temp.city, (char *)(record1+15*sizeof(char) + 20*sizeof(char)) );

  * (int *)(record1+0) = * (int *)(record2+0);
  strcpy((char *)(record1+sizeof(int)), (char *)(record2+sizeof(int)) );
  strcpy((char *)(record1+sizeof(int) + 15*sizeof(char)), (char *)(record2+sizeof(int) + 15*sizeof(char)) );
  strcpy((char *)(record1+15*sizeof(char) + 20*sizeof(char)), (char *)(record2+15*sizeof(char) + 20*sizeof(char)));

  * (int *)(record2+0) = temp.id;
  strcpy( (char *)(record2+sizeof(int)), temp.name );
  strcpy((char *)(record2+sizeof(int) + 15*sizeof(char)), temp.surname );
  strcpy((char *)(record2+15*sizeof(char) + 20*sizeof(char)), temp.city );

  //printf("sygkrina %d %s me %d %s \n", temp.id,temp.name, (char *)(record2+sizeof(int)) );

}