Best way to convert Pascal Case to a sentence

Question

What is the best way to convert from Pascal Case (upper Camel Case) to a sentence.

For example starting with

\"AwaitingFeedback\"

a

Answer 1

It is easy to do in JavaScript (or PHP, etc.) where you can define a function in the replace call:

var camel = "AwaitingFeedbackDearMaster";
var sentence = camel.replace(/([A-Z].)/g, function (c) { return ' ' + c.toLowerCase(); });
alert(sentence);

Although I haven't solved the initial cap problem... :-)

Now, for the Java solution:

String ToSentence(String camel)
{
  if (camel == null) return ""; // Or null...
  String[] words = camel.split("(?=[A-Z])");
  if (words == null) return "";
  if (words.length == 1) return words[0];
  StringBuilder sentence = new StringBuilder(camel.length());
  if (words[0].length() > 0) // Just in case of camelCase instead of CamelCase
  {
    sentence.append(words[0] + " " + words[1].toLowerCase());
  }
  else
  {
    sentence.append(words[1]);
  }
  for (int i = 2; i < words.length; i++)
  {
    sentence.append(" " + words[i].toLowerCase());
  }
  return sentence.toString();
}

System.out.println(ToSentence("AwaitingAFeedbackDearMaster"));
System.out.println(ToSentence(null));
System.out.println(ToSentence(""));
System.out.println(ToSentence("A"));
System.out.println(ToSentence("Aaagh!"));
System.out.println(ToSentence("stackoverflow"));
System.out.println(ToSentence("disableGPS"));
System.out.println(ToSentence("Ahh89Boo"));
System.out.println(ToSentence("ABC"));

Note the trick to split the sentence without loosing any character...

Answer 2

Here's a basic way of doing it that I came up with using Regex

public static string CamelCaseToSentence(this string value)
{
    var sb = new StringBuilder();
    var firstWord = true;

    foreach (var match in Regex.Matches(value, "([A-Z][a-z]+)|[0-9]+"))
    {
        if (firstWord)
        {
            sb.Append(match.ToString());
            firstWord = false;
        }
        else
        {
            sb.Append(" ");
            sb.Append(match.ToString().ToLower());
        }
    }

    return sb.ToString();
}

It will also split off numbers which I didn't specify but would be useful.

Answer 3

Found this in the MvcContrib source, doesn't seem to be mentioned here yet.

return Regex.Replace(input, "([A-Z])", " $1", RegexOptions.Compiled).Trim();

Answer 4

Pseudo-code:

NewString = "";
Loop through every char of the string (skip the first one)
   If char is upper-case ('A'-'Z')
     NewString = NewString + ' ' + lowercase(char)
   Else
     NewString = NewString + char

Better ways can perhaps be done by using regex or by string replacement routines (replace 'X' with ' x')

Answer 5

This is just like @SSTA, but is more efficient than calling TrimStart.

Regex.Replace("ThisIsMyCapsDelimitedString", "(\\B[A-Z])", " $1")

Answer 6

Found myself doing something similar, and I appreciate having a point-of-departure with this discussion. This is my solution, placed as an extension method to the string class in the context of a console application.

using System;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string piratese = "avastTharMatey";
            string ivyese = "CheerioPipPip";

            Console.WriteLine("{0}\n{1}\n", piratese.CamelCaseToString(), ivyese.CamelCaseToString());
            Console.WriteLine("For Pete\'s sake, man, hit ENTER!");
            string strExit = Console.ReadLine();
        }

    }

    public static class StringExtension
    {
        public static string CamelCaseToString(this string str)
        {
            StringBuilder retVal = new StringBuilder(32);

            if (!string.IsNullOrEmpty(str))
            {
                string strTrimmed = str.Trim();

                if (!string.IsNullOrEmpty(strTrimmed))
                {
                    retVal.Append(char.ToUpper(strTrimmed[0]));

                    if (strTrimmed.Length > 1)
                    {
                        for (int i = 1; i < strTrimmed.Length; i++)
                        {
                            if (char.IsUpper(strTrimmed[i])) retVal.Append(" ");

                            retVal.Append(char.ToLower(strTrimmed[i]));
                        }
                    }
                }
            }
            return retVal.ToString();
        }
    }
}