Modern C++ Programming with Test-Driven Development

2.17 Finishing Up

What about vowels? Rule #3 also states that otherwise-duplicate encodings separated by a vowel (not ​h​ or ​w​) get coded twice.

TEST_F(SoundexEncoding, DoesNotCombineDuplicateEncodingsSeparatedByVowels) {
   ASSERT_THAT(soundex.encode("Jbob"), Eq("J110"));
}

Once again we solve our challenge by declaring ​what​ we want to accomplish. We change the conditional expression in ​encodeLetter​ to append a digit only if it is not a duplicate ​or​ if the last letter is a vowel. This declaration drives a few corresponding changes.

void encodeTail(std::string& encoding, const std::string& word) const {
   for (auto i = 1u; i < word.length(); i++)
      if (!isComplete(encoding)) ...