I want “(int)null” to return me 0

Question

How can i get 0 as integer value from (int)null.

EDIT 1: I want to create a function that will return me default values for null representa

Answer 1

A generic method that returns a cast instance of an object or the default value could be implemented as follows:

static T Cast<T>(object value) {
    if (value is T)
        return (T)value;
    else
        return default(T);
}

This way, using a valid value will yield the value itself:

int value = Cast<int>(4); //value = 4

and a null value will get the default:

int value = Cast<int>(null); //value = 0

Notice that since the method takes object as an argument, this will cause boxing when used with struct objects (like int).

Answer 2

You can use the default keyword to get the default value of any data type:

int x = default(int);        //  == 0
string y = default(string);  //  == null
// etc.

This works with generic parameters as well:

Bar<T> Foo<T>() {
    return new Bar<T>(default(T));
}

---

In case you have a variable of type object that may contain null or a value of type int, you can use nullable types and the ?? operator to convert it safely to an integer:

int a = 42;
object z = a;
int b = (int?)z ?? 0;        //  == 42
int c = (int?)null ?? 0;     //  == 0