#nullable enable

​

using System;

using System.Globalization;

using System.Linq;

using System.Threading;

​

public class Program

{

    public static void Main()

    {

        var en =  CultureInfo.GetCultureInfo("en-US");

        var fr =  CultureInfo.GetCultureInfo("fr-fr");

        Thread.CurrentThread.CurrentUICulture = en;

​

        Console.WriteLine("Hello World".SwapCase());        // hELLO wORLD

        Console.WriteLine("Hello World".IsAlphanumeric());  // False

        Console.WriteLine("123456".IsAlphanumeric());       // True

        Console.WriteLine("123a456".IsAlphanumeric('a'));   // True

        Console.WriteLine("123b456".IsAlphanumeric('a'));   // False

        Console.WriteLine("Test".Center(10, '.'));          // ...Test...

        Console.WriteLine("Test".Center(15, '.'));          // .....Test......

        Console.WriteLine("Test".Center(2, '.'));           // Test

        Console.WriteLine("this is a test".ToTitleCase());  // This Is A Test

        Console.WriteLine("this is a test".IsTitleCase());  // False

        Console.WriteLine("This Is A Test".IsTitleCase());  // True

        Console.WriteLine("12ab3.45".ValueCount('a'));      // 2

        Console.WriteLine("23ab4.56".GetDigits());          // 23456

        Console.WriteLine("34ab5.67".GetDigits(true));      // 345.67

        Console.WriteLine("45ab6.78".GetDigits(true, en));  // 456.78

        Console.WriteLine("56ab7,89".GetDigits(true, en));  // 56789

​

        Console.WriteLine("67ab8.90".GetDigits(true, fr));  // 67890

        Console.WriteLine("782ab9,01".GetDigits(true, fr)); // 7829,01

        Console.WriteLine("89ab0.12".GetDouble());          // 890.12

        Console.WriteLine("90ab1.23".GetUInt());            // 90123

​

        Console.WriteLine("01ab2,34".GetDouble(en));        // 1234

        Console.WriteLine("01ab2,34".GetDouble(fr));        // 12.34

    }

}

​

public static class StringProcessing

{

    public static string SwapCase(this string value)

        => string.Join(string.Empty, value.Select(c => char.IsUpper(c) ? char.ToLower(c) : char.ToUpper(c)));

​

    public static bool IsAlphanumeric(this string value, params char[] ignoreChars)

        => value.All(c => char.IsDigit(c) || ignoreChars.Contains(c));

​

    public static int ValueCount(this string value, char count)

        => value.Where(c => c == count).Count();

​

    public static string Center(this string value, int totalLength, char padChar = ' ')

        => value.PadLeft(((totalLength - value.Length) / 2) + value.Length, padChar).PadRight(totalLength, padChar);

​

    public static string ToTitleCase(this string value)

        => string.Join(' ', value.Split().Select(word => char.ToUpper(word[0]) + word[1..].ToLower()));

​

    public static bool IsTitleCase(this string value)

        => value.Split().All(word => char.IsUpper(word[0]) && word[1..].All(char.IsLower));

​

    public static string GetDigits(this string value, bool allowDecimalSeparator = false, CultureInfo? culture = null)

        => string.Join(string.Empty, value.Where(c => char.IsDigit(c) || (allowDecimalSeparator && IsDecimalSeparator(c, culture))));

​

    public static double GetDouble(this string value, CultureInfo? culture = null)

        => double.Parse(GetDigits(value, true, GetCulture(culture)), GetCulture(culture));

​

    public static uint GetUInt(this string value, CultureInfo? culture = null)

        => uint.Parse(GetDigits(value, false, GetCulture(culture)), GetCulture(culture));

​

    private static bool IsDecimalSeparator(char value, CultureInfo? culture = null)

        => GetCulture(culture).NumberFormat.NumberDecimalSeparator.Equals(value.ToString());

​

    private static CultureInfo GetCulture(CultureInfo? culture = null)

        => culture ?? CultureInfo.CurrentUICulture;

}