How to make a Generic Type Cast function [duplicate]

Answer 1

Something like this?

public static T ConvertValue<T>(string value)
{
    return (T)Convert.ChangeType(value, typeof(T));
}

You can then use it like this:

int val = ConvertValue<int>("42");

Edit:

You can even do this more generic and not rely on a string parameter provided the type U implements IConvertible - this means you have to specify two type parameters though:

public static T ConvertValue<T,U>(U value) where U : IConvertible
{
    return (T)Convert.ChangeType(value, typeof(T));
}

I considered catching the InvalidCastException exception that might be raised by Convert.ChangeType() - but what would you return in this case? default(T)? It seems more appropriate having the caller deal with the exception.

Answer 2

ConvertValue( System.Object o ), then you can branch out by o.GetType() result and up-cast o to the types to work with the value.

Answer 3

While probably not as clean looking as the IConvertible approach, you could always use the straightforward checking typeof(T) to return a T:

public static T ReturnType<T>(string stringValue)
{
    if (typeof(T) == typeof(int))
        return (T)(object)1;
    else if (typeof(T) == typeof(FooBar))
        return (T)(object)new FooBar(stringValue);
    else
        return default(T);
}

public class FooBar
{
    public FooBar(string something)
    {}
}