The judgment and conversion of the type are the 2 operators of IS and as. Specific differences and usage are as follows
IS is the judgment of the type. Returns True and false. Returns True if an object is of a type or its parent type, otherwise it returns false. In addition, the IS operator never throws an exception. The code is as follows:
System.Boolean B1 = (O is System.Object);//b1 true
System.Boolean B2 = (O is Employee);//b2 False if the object reference is null, the IS operator always returns false because no object can check its type, just like the code below
If (O is Employee) {
Employee E = (employee) O;
Use e in the IF statement
in the above code, the CLR actually checks the object type two times: The is operation first checks whether the object referenced by O is compatible with the employee type. If compatible, the CLR checks whether O is an employee reference in the IF statement when it performs the conversion. This programming paradigm is very common, and C # provides a new type-checking, conversion method. As operator, he can improve performance while simplifying the code. The code is as follows:
Employee E = o as Employee;
if (E! = null)
{
Use e in the IF statement
This as operation improves performance even if it is equivalent to the above code, and only 1 types are checked. Returns a non-null reference if the type is the same, or returns a null reference.
The difference between C # is and as
