typeof: how to get type from string

You can use Type.GetType() to get a type from its string name. So you can do:

Type DateType = Type.GetType("System.DateTime");

You can't just use "DateTime" since that's not the type's name. If you do this and the name is wrong (it doesn't exist) then it'll throw an exception. So you'll need a try/catch around this.

You can get the proper type name for any given object by doing:

string TypeName = SomeObject.GetType().FullName;

If you need to use vague or incomplete names, then you're going to have a fun time messing around with reflection. Not impossible, but certainly a pain.

try
{
    // Get the type of a specified class.
    Type myType1 = Type.GetType("System.DateTime");
    Console.WriteLine("The full name is {myType1.FullName}.");

    // Since NoneSuch does not exist in this assembly, GetType throws a TypeLoadException.
    Type myType2 = Type.GetType("NoneSuch", true);
    Console.WriteLine("The full name is {myType2.FullName}.");
}
catch(TypeLoadException e)
{
    Console.WriteLine(e.Message);
}
catch(Exception e)
{
    Console.WriteLine(e.Message);
}

See Type.GetType(string) on MSDN