C# generic method with integer constraint refuses to cast from integer to the generic type

Question

If I have a generic method that is constrained to be type \'int\' then surely I should be able to cast an integer to the generic T type. For example...

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Answer 1

"Only class or interface could be specified as constraint." (c) ReSharper

int (Int32) is just a struct. You can constrain that T is a struct. but you can't use any struct as constraint.

the whole list of possible constraints you can find here - http://msdn.microsoft.com/en-us/library/d5x73970.aspx

UPD

and for Enum constraint see this question - Is there a workaround for generic type constraint of "special class" Enum in C# 3.0?

Answer 2

int (and all other numeric types, and enums) cannot be used as a generic constraint.

See

Generic C# Code and the Plus Operator

for further details and options.

For a discussion with Anders Hejlsberg, the creator of C#, about generics and type constraints see

http://www.artima.com/intv/generics.html

One can place a type constraint of struct like this:

public class Generic<T> where T : struct { }

Generic<int> gen = new Generic<int>();

Answer 3

Are you sure its compiling?

Here, it gives following error:

error CS0701: 'int' is not a valid constraint. A type used as a constraint must be an interface, a non-sealed class or a type parameter.