c# - Extension method is not working,If method in nonstatic class? -

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• why extension methods allowed in non-nested, non-generic static class? 3 answers

just read extension methods.i created static method inside static class working fine.

    static class extensionmethods     {         public static string splitfirstname(this string strname)         {             return strname.split(" ".tochararray())[0];         }      } 

but if create static method inside nonstatic class not working.

    class nonstaticcls     {       public static string splitfirstname(this string strname)       {         return strname.split(" ".tochararray())[0];       }     } 

please tell why not working in nonstatic class.

please tell why not working in nonstatic class.

because that's how extension methods specified. must declared in non-nested, non-generic class.

from section 10.6.9 of c# 5 specification:

when first parameter of method includes modifier, method said extension method. extension methods can declared in non-generic, non-nested static classes. first parameter of extension method can have no modifiers other this, , parameter type cannot pointer type.

why want declare in non-static class? trying achieve can't achieved equally using static class? (i can just imagine possibilities, they're not things i've ever wanted in extension methods myself...)