ToPascalCase

ToPascalCase.cs

using System;
using System.Diagnostics;
using System.Text;
					
public class NotThreadSafeHelper
{
	private static readonly StringBuilder _StringBuilderCached = new();
	
	// Not thread safe! Reuses a static buffer.
	public static string ToPascalCase(ReadOnlySpan<char> input)
	{
		ToPascalCase(input, _StringBuilderCached);
		return _StringBuilderCached.ToString();
	}
	
	public static void ToPascalCase(ReadOnlySpan<char> input, StringBuilder output)
	{
		output.Clear();
		
		int i = 0;
		if (input.Length == 0)
			return;

		{
			char ch = input[i];
			i++;

			if (ch >= 'a' && ch <= 'z')
				output.Append((char)(ch + 'A' - 'a'));
			else if (ch != ' ' && ch != '_' && ch != '-')
				output.Append(ch);
		}

		while (i != input.Length)
		{
			char ch = input[i];
			i++;

			if (ch == ' ' || ch == '_' || ch == '-')
			{
				if (i == input.Length)
					break;
				ch = input[i];
				if (ch >= 'a' && ch <= 'z')
				{
					output.Append((char)(ch + 'A' - 'a'));
					i++;
				}
			}
			else
			{
				output.Append(ch);
			}
		}
	}
	
	public static void Main()
	{
		Debug.Assert(ToPascalCase("abc") == "ABC");
		Debug.Assert(ToPascalCase("camelCase") == "CamelCase");
		Debug.Assert(ToPascalCase("aa-bb-cc") == "AaBbCc");
		Debug.Assert(ToPascalCase("hello_world") == "HelloWorld");
		Debug.Assert(ToPascalCase("123kf") == "123kf");
	}
}