What is the difference between Convert.ToInt32 and (int)?

Question

The following code throws an compile-time error like

Cannot convert type \'string\' to \'int\'

string name = Session[\"name1\"].ToString();
int i = (         


        

Answer 1

To quote from this Eric Lippert article:

Cast means two contradictory things: "check to see if this object really is of this type, throw if it is not" and "this object is not of the given type; find me an equivalent value that belongs to the given type".

So what you were trying to do in 1.) is assert that yes a String is an Int. But that assertion fails since String is not an int.

The reason 2.) succeeds is because Convert.ToInt32() parses the string and returns an int. It can still fail, for example:

Convert.ToInt32("Hello");

Would result in an Argument exception.

To sum up, converting from a String to an Int is a framework concern, not something implicit in the .Net type system.