-

mystring base64tobinary(mystring source)
{ 
  int i;
  int index;
  char base64[64] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  char *tmp;
  char *chunk;
  for (i = 0; i < source.length; i++)
  { 
    tmp = strchr(base64, source.text[i]);
    index = (int) (tmp - base64);
    chunk = dectobinary(index);
    printf("%s\n", chunk);
  }
}

char* dectobinary(int source)
{ 
  char result[7];
  result[0] = '\0';
  int i, k;
  for (i = 5; i >= 0; i--)
  { 
    k = source >> i;

    if (k & 1)
      strcat(result, "1");
    else
      strcat(result, "0");
  }
  return result;
}