Cast.Cast<int?> applied on generic enum collection results in invalid cast exception

Question

enum Gender { Male, Female }

var k = new[] { Gender.Male }.Cast().ToList().Cast().ToList(); //alright

var p = new[] { Gender.Male }.Cast<         


        

Answer 1

This is due to deferred execution. The latter statement actually tries to cast Gender.Male to int?. In contrast, the first statement actually performs the cast operation to an int and gets a List before deferring the execution to cast those to int?; clearly int to int? has an implicity conversion defined already.