Since Int32 is a value type why does it inherit .ToString()?

Question

These are the docs about .ToString() that has prompted this question. They state:

Because Object is the base class of all reference types in the .NET Framework, this behavior [.ToString()] is inherited by reference types that do not override the ToString method.

Yet further on it goes to state:

For example, the base types such as Char, Int32, and String provide ToString implementations

However Int32 is a struct and hence must be a value type.

So what's going on here? Does Int32 implement it's very own .ToString() which has nothing to do with Object?

Answer 1

Int32 is a struct and therefore a value type. But:

System.Object
   System.ValueType
      System.Int32

Int32 derives from System.ValueType and this itself derives from System.Object. Et voilà...

Answer 2

Yes, Int32 overrides ToString... although that's somewhat irrelevant here. All types inherit the members of object - you can always call ToString(), you can always call Equals etc. (ValueType overrides Equals and GetHashCode for you, although you should almost always override them further in structs to provide a more efficient implementation.)

Note that you can override the methods yourself very easily:

public struct Foo
{
    public override string ToString()
    {
        return "some dummy text";
    }
}

It's not clear which aspect is confusing you (there are quite a few different areas involved here). If you could clarify, we could address the specific issue.

Answer 3

Perhaps you confusion arises from not realizing that value types inherit from Object? Here is the inheritance graph of System.Object, System.ValueType, System.Int32 and MyNamespace.Customer which is supposed to be a class of you own making. I was lazy and didn't write all the public methods and interfaces of Int32.

ToString is declared in Object but is overriden both in ValueType and in Int32.