Best way to convert Pascal Case to a sentence

Question

public static string ToSentenceCase(this string str)
{
    return Regex.Replace(str, "[a-z][A-Z]", m => m.Value[0] + " " + char.ToLower(m.Value[1]));
}

In versions of visual studio after 2015, you can do

public static string ToSentenceCase(this string str)
{
    return Regex.Replace(str, "[a-z][A-Z]", m => $"{m.Value[0]} {char.ToLower(m.Value[1])}");
}

Based on: Converting Pascal case to sentences using regular expression

I will prefer to use Humanizer for this. Humanizer is a Portable Class Library that meets all your .NET needs for manipulating and displaying strings, enums, dates, times, timespans, numbers and quantities.

Short Answer

"AwaitingFeedback".Humanize() => Awaiting feedback

Long and Descriptive Answer

Humanizer can do a lot more work other examples are:

"PascalCaseInputStringIsTurnedIntoSentence".Humanize() => "Pascal case input string is turned into sentence"
"Underscored_input_string_is_turned_into_sentence".Humanize() => "Underscored input string is turned into sentence"
"Can_return_title_Case".Humanize(LetterCasing.Title) => "Can Return Title Case"
"CanReturnLowerCase".Humanize(LetterCasing.LowerCase) => "can return lower case"

Complete code is :

using Humanizer;
using static System.Console;

namespace HumanizerConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            WriteLine("AwaitingFeedback".Humanize());
            WriteLine("PascalCaseInputStringIsTurnedIntoSentence".Humanize());
            WriteLine("Underscored_input_string_is_turned_into_sentence".Humanize());
            WriteLine("Can_return_title_Case".Humanize(LetterCasing.Title));
            WriteLine("CanReturnLowerCase".Humanize(LetterCasing.LowerCase));
        }
    }
}

Output

Awaiting feedback

Pascal case input string is turned into sentence

Underscored input string is turned into sentence Can Return Title Case

can return lower case

If you prefer to write your own C# code you can achieve this by writing some C# code stuff as answered by others already.

Here you go...

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CamelCaseToString
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(CamelCaseToString("ThisIsYourMasterCallingYou"));   
        }

        private static string CamelCaseToString(string str)
        {
            if (str == null || str.Length == 0)
                return null;

            StringBuilder retVal = new StringBuilder(32);

            retVal.Append(char.ToUpper(str[0]));
            for (int i = 1; i < str.Length; i++ )
            {
                if (char.IsLower(str[i]))
                {
                    retVal.Append(str[i]);
                }
                else
                {
                    retVal.Append(" ");
                    retVal.Append(char.ToLower(str[i]));
                }
            }

            return retVal.ToString();
        }
    }
}

This works for me:

Regex.Replace(strIn, "([A-Z]{1,2}|[0-9]+)", " $1").TrimStart()

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

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

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

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