C# Object Type Comparison

Question

How can I compare the types of two objects declared as type.

I want to know if two objects are of the same type or from the same base class.

Any help is appreciated.

e.g.

private bool AreSame(Type a, Type b) {  } 

Answer 1

Say a and b are the two objects. If you want to see if a and b are in the same inheritance hierarchy, then use Type.IsAssignableFrom:

var t = a.GetType(); var u = b.GetType();  if (t.IsAssignableFrom(u) || u.IsAssignableFrom(t)) {   // x.IsAssignableFrom(y) returns true if:   //   (1) x and y are the same type   //   (2) x and y are in the same inheritance hierarchy   //   (3) y is implemented by x   //   (4) y is a generic type parameter and one of its constraints is x } 

If you want to check if one is a base class of the other, then try Type.IsSubclassOf.

If you know the specific base class, then just use the is keyword:

if (a is T && b is T) {   // Objects are both of type T. } 

Otherwise, you'll have to walk the inheritance hierarchy directly.

Answer 2

There's a bit of a problem with this idea, though, as every object (and, indeed, every type) DOES have a common base class, Object. What you need to define is how far up the chain of inheritance you want to go (whether it's they're either the same or they have the same immediate parent, or one is the immediate parent of the other, etc.) and do your checks that way. IsAssignableFrom is useful for determining if types are compatible with one another, but won't fully establish if they have the same parent (if that's what you're after).

If your strict criteria is that the function should return true if...

• The types are identical
• One type is the parent (immediate or otherwise) of the other
• The two types have the same immediate parent

You could use

private bool AreSame(Type a, Type b)  {     if(a == b) return true; // Either both are null or they are the same type      if(a == null || b == null) return false;       if(a.IsSubclassOf(b) || b.IsSubclassOf(a)) return true; // One inherits from the other      return a.BaseType == b.BaseType; // They have the same immediate parent }