Switch case and generics checking

Question

I want to write a function that format int and decimal differently into string

I have this code:

and I want to rewrite it to generics:

    public static string FormatAsIntWithCommaSeperator(int value)     {         if (value == 0 || (value > -1 && value < 1))             return "0";         return String.Format("{0:#,###,###}", value);     }      public static string FormatAsDecimalWithCommaSeperator(decimal value)     {         return String.Format("{0:#,###,###.##}", value);     }       public static string FormatWithCommaSeperator<T>(T value) where T : struct     {         string formattedString = string.Empty;          if (typeof(T) == typeof(int))         {             if ((int)value == 0 || (value > -1 && value < 1))             return "0";              formattedString = String.Format("{0:#,###,###}", value);         }          //some code...     }      /// <summary>     /// If the number is an int - returned format is without decimal digits     /// </summary>     /// <param name="value"></param>     /// <returns></returns>     public static string FormatNumberTwoDecimalDigitOrInt(decimal value)     {         return (value == (int)value) ? FormatAsIntWithCommaSeperator(Convert.ToInt32(value)) : FormatAsDecimalWithCommaSeperator(value);     } 

How can i use T in the function body?

What syntax should I use?

Answer 1

You can use the TypeCode enum for switch:

switch (Type.GetTypeCode(typeof(T))) {     case TypeCode.Int32:        ...        break;     case TypeCode.Decimal:        ...        break; } 

Since C# 7.0 you can use pattern matching:

switch (obj) {     case int i:        ...        break;     case decimal d:        ...        break;     case UserDefinedType u:        ...        break; } 

Beginning with C# 8.0 you can use switch expressions:

string result = obj switch {     int i => $"Integer {i}",     decimal d => $"Decimal {d}",     UserDefinedType u => "User defined {u}",     _ => "unexpected type" };