Equals and "==" operator

  • Thread starter Thread starter #Hai
  • Start date Start date
H

#Hai

Hi,
What is the difference between Object.Equals and "==" operator ?
When we use CollectionBase.List.Remove(object), which methods is used to
compare objects ?

Thanks
 
For interest, there are also performance differences between instance and
static(shared) methods for Equals and the == operator when comparing
strings.
 
Hi Anthony!

Can you tell me more about the performance differences. Which way is
fastest?

TIA,

Markus
 
Furthermore, not all languages support operator overloading. So, if one
wants to write language independent code she/he should not rely on operator
overloading. For c# convenince the operators might be overloaded and the
virtual method might be used internally.

B/rgds
100

Jon Skeet said:
[What does this have to do with Windows forms, by the way? Please limit
your post to relevant groups - preferrably only one!]

#Hai said:
What is the difference between Object.Equals and "==" operator ?
Click to expand...

Operators are not applied polymorphically, methods are. For instance:

string x = "hello";
string y = new string (x.ToCharArray());

object a=x;
object b=y;

x==y; // True, because String== is applied
a==b; // False, because Object== is applied, which asserts reference
// identity

x.Equals(y); // True, because String.Equals override Object.Equals
a.Equals(b); // True, because methods are invoked polymorphically
When we use CollectionBase.List.Remove(object), which methods is used to
compare objects ?
Click to expand...

Almost certainly Equals - it's the only way that makes sense, really,
given that CollectionBase only knows about Objects, so to remove
entries you'd have to have the exact reference if it used ==.
Click to expand...
 
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