c# String扩展 让你在PadLeft和PadRight时不再受单双字节问题困扰

  using System.Text.RegularExpressions;
  public static class StringExtensions
  {
    /// <summary>
    /// 按单字节字符串向左填充长度
    /// </summary>
    /// <param name="input"></param>
    /// <param name="length"></param>
    /// <param name="paddingChar"></param>
    /// <returns></returns>
    public static string PadLeftWhileDouble(this string input, int length, char paddingChar = '\0')
    {
      var singleLength = GetSingleLength(input);
      return input.PadLeft(length - singleLength + input.Length, paddingChar); 
    }
    private static int GetSingleLength(string input)
    {
      if (string.IsNullOrEmpty(input))
      {
        throw new ArgumentNullException();
      }
      return Regex.Replace(input, @"[^\x00-\xff]", "aa").Length;//计算得到该字符串对应单字节字符串的长度
    }
    /// <summary>
    /// 按单字节字符串向右填充长度
    /// </summary>
    /// <param name="input"></param>
    /// <param name="length"></param>
    /// <param name="paddingChar"></param>
    /// <returns></returns>
    public static string PadRightWhileDouble(this string input, int length, char paddingChar = '\0')
    {
      var singleLength = GetSingleLength(input);
      return input.PadRight(length - singleLength + input.Length, paddingChar);
    }
  }

      Console.WriteLine("123测试测试".PadRightWhileDouble(25) + "1");
      Console.WriteLine("123测试测试".PadRightWhileDouble(25, 'A') + "1");
      Console.WriteLine("1231212".PadRightWhileDouble(25) + "1");
      Console.WriteLine("1231212".PadRightWhileDouble(25, 'A') + "1");
      Console.WriteLine("123测试测试".PadLeftWhileDouble(25) + "1");
      Console.WriteLine("123测试测试".PadLeftWhileDouble(25, 'A') + "1");
      Console.WriteLine("1231212".PadLeftWhileDouble(25) + "1");
      Console.WriteLine("1231212".PadLeftWhileDouble(25, 'A') + "1");

for(int i=1;i<=4;i++)
{
 Console.WriteLine(string.Empty.PadLeft(i,'*'));
}