c# string capital first letter extension method
public static class StringExtensions
{
public static string FirstCharToUpper(this string input) =>
input switch
{
null => throw new ArgumentNullException(nameof(input)),
"" => throw new ArgumentException($"{nameof(input)} cannot be empty", nameof(input)),
_ => input.First().ToString().ToUpper() + input.Substring(1)
};
}