Question

Using this question as the base is there an alogrithm or coding example to change some text to Pascal or Camel casing.

For example:

mynameisfred 

becomes

Camel: myNameIsFred Pascal: MyNameIsFred 

Answer 1

I found a thread with a bunch of Perl guys arguing the toss on this question over at http://www.perlmonks.org/?node_id=336331.

I hope this isn’t too much of a non-answer to the question, but I would say you have a bit of a problem in that it would be a very open-ended algorithm which could have a lot of ‘misses’ as well as hits. For example, say you inputted:-

camelCase('hithisisatest'); 

The output could be:-

'hiThisIsATest' 

Or:-

'hitHisIsATest' 

There’s no way the algorithm would know which to prefer. You could add some extra code to specify that you’d prefer more common words, but again misses would occur (Peter Norvig wrote a very small spelling corrector over at http://norvig.com/spell-correct.html which might help algorithm-wise, I wrote a C# implementation if C#’s your language).

I’d agree with Mark and say you’d be better off having an algorithm that takes a delimited input, i.e. this_is_a_test and converts that. That’d be simple to implement, i.e. in pseudocode:-

SetPhraseCase(phrase, CamelOrPascal):     if no delimiters      if camelCase       return lowerFirstLetter(phrase)      else       return capitaliseFirstLetter(phrase)     words = splitOnDelimiter(phrase)     if camelCase        ret = lowerFirstLetter(first word)       else       ret = capitaliseFirstLetter(first word)     for i in 2 to len(words): ret += capitaliseFirstLetter(words[i])     return ret  capitaliseFirstLetter(word):     if len(word) <= 1 return upper(word)     return upper(word[0]) + word[1..len(word)]  lowerFirstLetter(word):     if len(word) <= 1 return lower(word)     return lower(word[0]) + word[1..len(word)] 

You could also replace my capitaliseFirstLetter() function with a proper case algorithm if you so wished.

A C# implementation of the above described algorithm is as follows (complete console program with test harness):-

using System;  class Program {   static void Main(string[] args) {      var caseAlgorithm = new CaseAlgorithm('_');      while (true) {       string input = Console.ReadLine();        if (string.IsNullOrEmpty(input)) return;        Console.WriteLine('Input '{0}' in camel case: '{1}', pascal case: '{2}'',         input,         caseAlgorithm.SetPhraseCase(input, CaseAlgorithm.CaseMode.CamelCase),         caseAlgorithm.SetPhraseCase(input, CaseAlgorithm.CaseMode.PascalCase));     }   } }  public class CaseAlgorithm {    public enum CaseMode { PascalCase, CamelCase }    private char delimiterChar;    public CaseAlgorithm(char inDelimiterChar) {     delimiterChar = inDelimiterChar;   }    public string SetPhraseCase(string phrase, CaseMode caseMode) {      // You might want to do some sanity checks here like making sure     // there's no invalid characters, etc.      if (string.IsNullOrEmpty(phrase)) return phrase;      // .Split() will simply return a string[] of size 1 if no delimiter present so     // no need to explicitly check this.     var words = phrase.Split(delimiterChar);      // Set first word accordingly.     string ret = setWordCase(words[0], caseMode);      // If there are other words, set them all to pascal case.     if (words.Length > 1) {       for (int i = 1; i < words.Length; ++i)         ret += setWordCase(words[i], CaseMode.PascalCase);     }      return ret;   }    private string setWordCase(string word, CaseMode caseMode) {     switch (caseMode) {       case CaseMode.CamelCase:         return lowerFirstLetter(word);       case CaseMode.PascalCase:         return capitaliseFirstLetter(word);       default:         throw new NotImplementedException(           string.Format('Case mode '{0}' is not recognised.', caseMode.ToString()));     }   }    private string lowerFirstLetter(string word) {     return char.ToLower(word[0]) + word.Substring(1);   }    private string capitaliseFirstLetter(string word) {     return char.ToUpper(word[0]) + word.Substring(1);   } }