c# - Using Generics to Multiply Integers -

i have class called genericitem (first time using generics), suppose wanted multiply 2 items if of type integer, can see trying in method returncountermultiply, not allow me multiply them although trying convert them , checking if of type integer.

namespace components {     public class genericitem<t>     {         private t data;         private t counter;          public t data         {             { return data; }             set { data = value; }         }          public genericitem(){}         public genericitem(t _data)         {             data = _data;         }          public t returncountermultiply(t value)         {             int c = 0;             int d = 0;             if (counter.gettype() == typeof(int) && value.gettype() == typeof(int))             {               //cant multiply 2 of type t, why if converting int?.                return (t)convert.changetype(counter, typeof(int32)) * (t)convert.changetype(value, typeof(int32));             }             return value;         }      } } 

i appreciate explanation on this first time working on (this sample class understanding generics intro , generics classes, still having trouble understanding it.

you can this:

public class genericitem<t> {     private t data;      public t data     {         { return data; }         set { data = value; }     }      public genericitem(){}     public genericitem(t _data)     {         data = _data;     }      private dictionary<type, delegate> operations =         new dictionary<type, delegate>()         {             { typeof(int), (func<int, int, int>)((x, y) => x * y) },             { typeof(string), (func<string, string, string>)((x, y) => x + " " + y) },         };      public t returncountermultiply(t value)     {         if (operations.containskey(typeof(t)))         {             var operation = (func<t, t, t>)(operations[typeof(t)]);             return operation(data, value);         }         return value;     } } 

you need define, in dictionary, 1 operation per valid types you're going want use , works without converting of types (except cast func).

i had these test results:

var gii = new genericitem<int>(42); var xi = gii.returncountermultiply(2); // xi == 84  var gis = new genericitem<string>("foo"); var xs = gis.returncountermultiply("bar"); // xs == "foo bar"