Does anyone have a good Proper Case algorithm

Question

Does anyone have a trusted Proper Case or PCase algorithm (similar to a UCase or Upper)? I'm looking for something that takes a value such as "GEORGE BURDELL" or "george burdell" and turns it into "George Burdell".

I have a simple one that handles the simple cases. The ideal would be to have something that can handle things such as "O'REILLY" and turn it into "O'Reilly", but I know that is tougher.

I am mainly focused on the English language if that simplifies things.

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UPDATE: I'm using C# as the language, but I can convert from almost anything (assuming like functionality exists).

I agree that the McDonald's scneario is a tough one. I meant to mention that along with my O'Reilly example, but did not in the original post.

Answer 1

Unless I've misunderstood your question I don't think you need to roll your own, the TextInfo class can do it for you.

using System.Globalization;  CultureInfo.InvariantCulture.TextInfo.ToTitleCase("GeOrGE bUrdEll") 

Will return "George Burdell. And you can use your own culture if there's some special rules involved.

Update: Michael (in a comment to this answer) pointed out that this will not work if the input is all caps since the method will assume that it is an acronym. The naive workaround for this is to .ToLower() the text before submitting it to ToTitleCase.

Answer 2

@zwol: I'll post it as a separate reply.

Here's an example based on ljs's post.

void Main() {     List<string> names = new List<string>() {         "bill o'reilly",          "johannes diderik van der waals",          "mr. moseley-williams",          "Joe VanWyck",          "mcdonald's",          "william the third",          "hrh prince charles",          "h.r.m. queen elizabeth the third",         "william gates, iii",          "pope leo xii",         "a.k. jennings"     };          names.Select(name => name.ToProperCase()).Dump(); }  // http://stackoverflow.com/questions/32149/does-anyone-have-a-good-proper-case-algorithm public static class ProperCaseHelper {     public static string ToProperCase(this string input)     {         if (IsAllUpperOrAllLower(input))         {             // fix the ALL UPPERCASE or all lowercase names             return string.Join(" ", input.Split(' ').Select(word => wordToProperCase(word)));         }         else         {             // leave the CamelCase or Propercase names alone             return input;         }     }      public static bool IsAllUpperOrAllLower(this string input)     {         return (input.ToLower().Equals(input) || input.ToUpper().Equals(input));     }      private static string wordToProperCase(string word)     {         if (string.IsNullOrEmpty(word)) return word;          // Standard case         string ret = capitaliseFirstLetter(word);          // Special cases:         ret = properSuffix(ret, "'");   // D'Artagnon, D'Silva         ret = properSuffix(ret, ".");   // ???         ret = properSuffix(ret, "-");       // Oscar-Meyer-Weiner         ret = properSuffix(ret, "Mc", t => t.Length > 4);      // Scots         ret = properSuffix(ret, "Mac", t => t.Length > 5);     // Scots except Macey          // Special words:         ret = specialWords(ret, "van");     // Dick van Dyke         ret = specialWords(ret, "von");     // Baron von Bruin-Valt         ret = specialWords(ret, "de");         ret = specialWords(ret, "di");         ret = specialWords(ret, "da");      // Leonardo da Vinci, Eduardo da Silva         ret = specialWords(ret, "of");      // The Grand Old Duke of York         ret = specialWords(ret, "the");     // William the Conqueror         ret = specialWords(ret, "HRH");     // His/Her Royal Highness         ret = specialWords(ret, "HRM");     // His/Her Royal Majesty         ret = specialWords(ret, "H.R.H.");  // His/Her Royal Highness         ret = specialWords(ret, "H.R.M.");  // His/Her Royal Majesty          ret = dealWithRomanNumerals(ret);   // William Gates, III          return ret;     }      private static string properSuffix(string word, string prefix, Func<string, bool> condition = null)     {         if (string.IsNullOrEmpty(word)) return word;         if (condition != null && ! condition(word)) return word;                  string lowerWord = word.ToLower();         string lowerPrefix = prefix.ToLower();          if (!lowerWord.Contains(lowerPrefix)) return word;          int index = lowerWord.IndexOf(lowerPrefix);          // If the search string is at the end of the word ignore.         if (index + prefix.Length == word.Length) return word;          return word.Substring(0, index) + prefix +             capitaliseFirstLetter(word.Substring(index + prefix.Length));     }      private static string specialWords(string word, string specialWord)     {         if (word.Equals(specialWord, StringComparison.InvariantCultureIgnoreCase))         {             return specialWord;         }         else         {             return word;         }     }      private static string dealWithRomanNumerals(string word)     {         // Roman Numeral parser thanks to [djk](https://stackoverflow.com/users/785111/djk)         // Note that it excludes the Chinese last name Xi         return new Regex(@"\b(?!Xi\b)(X|XX|XXX|XL|L|LX|LXX|LXXX|XC|C)?(I|II|III|IV|V|VI|VII|VIII|IX)?\b", RegexOptions.IgnoreCase).Replace(word, match => match.Value.ToUpperInvariant());     }      private static string capitaliseFirstLetter(string word)     {         return char.ToUpper(word[0]) + word.Substring(1).ToLower();     }  }