-

mystring binarytohex(mystring source)
{
  int i;
  char chunk[4];
  char hexchar;
  mystring result;
  result.text[0] = '\0';
  result.length = 0;

  for(i = 0; i < source.length; i++)
  {
    if (i > 0 && i % 4 == 0)
    {
      binaryquadtohexchar(chunk, &hexchar);
      result.text[result.length] = hexchar;
      result.text[result.length+1] = '\0';
      result.length = strlen(result.text);
      printf("%c\n", hexchar);
    }
    chunk[i % 4] = source.text[i];
    if (i == source.length-1)
    {
      binaryquadtohexchar(chunk, &hexchar);
      printf("%c\n", hexchar);
    }

  }

}

char binaryquadtohexchar(char * source, char *result)
{ 
  int i;
  char * hexquads[] = {
    "0000",
    "0001",
    "0010",
    "0011",
    "0100",
    "0101",
    "0110",
    "0111",
    "1000",
    "1001",
    "1010",
    "1011",
    "1100",
    "1101",
    "1110",
    "1111",
  };
  char hexchars[] = {
    '0',
    '1',
    '2',
    '3',
    '4',
    '5',
    '6',
    '7',
    '8',
    '9',
    'a',
    'b',
    'c',
    'd',
    'e',
    'f'
  };

  for (i = 0; i <= 15; i++)
  { 
    if (strcmp(source, hexquads[i]) == 0)
    {
      *result = hexchars[i];
    }
  }
}