using System;

using System.Linq;

​

public static class StringExtensions

{

    /// <summary>

    /// Converts a string to PascalCase

    /// </summary>

    /// <remarks>Does not modify the original string</remarks>

​

    /// <param name="str">String to convert</param>

​

    public static string ToPascalCase(this string str){

        // Replace all non-letter and non-digits with an underscore and lowercase the rest.

        string sample = string.Join("", str?.Select(c => Char.IsLetterOrDigit(c) ? c.ToString().ToLower() : "_").ToArray());

        // Split the resulting string by underscore

        // Select first character, uppercase it and concatenate with the rest of the string

        var arr = sample?

            .Split(new []{'_'}, StringSplitOptions.RemoveEmptyEntries)

            .Select(s => $"{s.Substring(0, 1).ToUpper()}{s.Substring(1)}");

        // Join the resulting collection

        sample = string.Join("", arr);

        return sample;

    }

}

public class Program

{

    public static void Main()

    {

        Console.WriteLine("WARD_VS_VITAL_SIGNS".ToPascalCase()); // WardVsVitalSigns

        Console.WriteLine("Who am I?".ToPascalCase()); // WhoAmI

        Console.WriteLine("I ate before you got here".ToPascalCase()); // IAteBeforeYouGotHere

        Console.WriteLine("Hello|Who|Am|I?".ToPascalCase()); // HelloWhoAmI

        Console.WriteLine("Live long and prosper".ToPascalCase()); // LiveLongAndProsper

        Console.WriteLine("Lorem ipsum dolor sit amet, consectetur adipiscing elit.".ToPascalCase()); // LoremIpsumDolorSitAmetConsecteturAdipiscingElit

    }

}