What is a mutable type?

[Simon Woods]

Hi

I wonder if someone could explain the above to me. The examples I've
seen seem to indicate that it is effectively a read-only class, but I'm
sure that's being over simplistic. But what is the significance of them?

Thanks

Simon

 

[Guest]

mutable: capable or subject to change

I think you are thinking of immutable. Strings are immutable.

 

[Guest]

Forgot about 'what is the signicance'.

Most things are mutable, its the immutable things that have to be handled
differently.

Sub Main()
Dim s1 As String = "123"
Dim s2 As String = s1
Console.WriteLine("{0}", (s1 Is s2))
s1 = s1 & "45"
Console.WriteLine("{0}", (s1 Is s2))
Console.ReadLine()
End Sub
The output is
True
False
So when you attemped to change s1, a brand new string object was created
with value "12345" and s1 points to it.