I've a really strange problem, in some part of my code I compare two
strings (through object), and while I *know* that they equal each
other, and in the watch window they do equal each other, then the
comparision return false.
See here for details: http://www.ayende.com/Blog/PermaLink...c876a6acb.aspx 11  2472 
Ayende Rahien wrote: I've a really strange problem, in some part of my code I compare two
strings (through object), and while I *know* that they equal each
other, and in the watch window they do equal each other, then the
comparision return false.
See here for details:
http://www.ayende.com/Blog/PermaLink...34f-bfe0-39ac8
76a6acb.aspx
The problem is that "strings" are neither reference types nor value types!
They are handled in a special way...
In your case you are comparing object references which might be different!
Either use string.Compare( a, b) or a.CompareTo(b) or a.Equals(b)
--
Greetings
Jochen
My blog about Win32 and .NET http://blog.kalmbachnet.de/
The code that is failing is the
if( o == test) ?
well o and test are both typed as object so you are using the System.Object == operator which hands off to System.Object.R eferenceEquals. In other words, the comparison will onyl succeed if o and test are teh same physical object
Regards
Richard Blewett - DevelopMentor http://staff.develop.com/richardb/weblog
nntp://news.microsoft. com/microsoft.publi c.dotnet.langua ges.csharp/<29************ *************@p osting.google.c om>
I've a really strange problem, in some part of my code I compare two
strings (through object), and while I *know* that they equal each
other, and in the watch window they do equal each other, then the
comparision return false.
See here for details: http://www.ayende.com/Blog/PermaLink...c876a6acb.aspx
---
Incoming mail is certified Virus Free.
Checked by AVG anti-virus system ( http://www.grisoft.com).
Version: 6.0.771 / Virus Database: 518 - Release Date: 28/09/2004
[microsoft.publi c.dotnet.langua ges.csharp]
Umm, strings are reference types. They are immutable which results in some value like behavior but they are definitely reference types (i.e. allocated on the managed heap, referred to vai a 32 bit reference and are garbage collected.
Regards
Richard Blewett - DevelopMentor http://staff.develop.com/richardb/weblog
nntp://news.microsoft. com/microsoft.publi c.dotnet.langua ges.csharp/<Xn************ *************** *******@207.46. 248.16>
Ayende Rahien wrote: I've a really strange problem, in some part of my code I compare two
strings (through object), and while I *know* that they equal each
other, and in the watch window they do equal each other, then the
comparision return false.
See here for details:
http://www.ayende.com/Blog/PermaLink...34f-bfe0-39ac8
76a6acb.aspx
The problem is that "strings" are neither reference types nor value types!
They are handled in a special way...
In your case you are comparing object references which might be different!
Either use string.Compare( a, b) or a.CompareTo(b) or a.Equals(b)
--
Greetings
Jochen
My blog about Win32 and .NET http://blog.kalmbachnet.de/
---
Incoming mail is certified Virus Free.
Checked by AVG anti-virus system ( http://www.grisoft.com).
Version: 6.0.771 / Virus Database: 518 - Release Date: 28/09/2004
[microsoft.publi c.dotnet.langua ges.csharp]
Jochen Kalmbach <no************ ********@holzma .de> wrote: Ayende Rahien wrote:
I've a really strange problem, in some part of my code I compare two
strings (through object), and while I *know* that they equal each
other, and in the watch window they do equal each other, then the
comparision return false.
See here for details:
http://www.ayende.com/Blog/PermaLink...34f-bfe0-39ac8
76a6acb.aspx
The problem is that "strings" are neither reference types nor value types!
They are handled in a special way...
That's not true. String is a reference type which overrides operator==.
In what way do you believe they're not reference types?
--
Jon Skeet - <sk***@pobox.co m> http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
Jon Skeet [C# MVP] wrote: > http://www.ayende.com/Blog/PermaLink...0-434f-bfe0-39
> ac8 76a6acb.aspx
The problem is that "strings" are neither reference types nor value
types! They are handled in a special way...
That's not true. String is a reference type which overrides
operator==.
In what way do you believe they're not reference types?
As Richard explains:
They are immutable which results in some value like behavior but they are
definitely reference types.
--
Greetings
Jochen
My blog about Win32 and .NET http://blog.kalmbachnet.de/
Try here for a full sample, this should *never* happen. http://www.ayende.com/Blog/PermaLink...f4d261dc0.aspx
"Richard Blewett [DevelopMentor]" wrote: The code that is failing is the
if( o == test) ?
well o and test are both typed as object so you are using the System.Object == operator which hands off to System.Object.R eferenceEquals. In other words, the comparison will onyl succeed if o and test are teh same physical object
Regards
Richard Blewett - DevelopMentor
http://staff.develop.com/richardb/weblog
nntp://news.microsoft. com/microsoft.publi c.dotnet.langua ges.csharp/<29************ *************@p osting.google.c om>
I've a really strange problem, in some part of my code I compare two
strings (through object), and while I *know* that they equal each
other, and in the watch window they do equal each other, then the
comparision return false.
See here for details:
http://www.ayende.com/Blog/PermaLink...c876a6acb.aspx
---
Incoming mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.771 / Virus Database: 518 - Release Date: 28/09/2004
[microsoft.publi c.dotnet.langua ges.csharp]
Ummm - thats where I went to find the if( o == test) piece of code. What do you mean by "this should never happen"? If you have two System.Object references compared by using the == operator then it will erform a reference check as I said becasue operator overloads are not virtual.
Regards
Richard Blewett - DevelopMentor http://staff.develop.com/richardb/weblog
nntp://news.microsoft. com/microsoft.publi c.dotnet.langua ges.csharp/<5B************ *************** *******@microso ft.com>
Try here for a full sample, this should *never* happen. http://www.ayende.com/Blog/PermaLink...f4d261dc0.aspx
"Richard Blewett [DevelopMentor]" wrote: The code that is failing is the
if( o == test) ?
well o and test are both typed as object so you are using the System.Object == operator which hands off to System.Object.R eferenceEquals. In other words, the comparison will onyl succeed if o and test are teh same physical object
Regards
Richard Blewett - DevelopMentor
http://staff.develop.com/richardb/weblog
Jochen Kalmbach <no************ ********@holzma .de> wrote: The problem is that "strings" are neither reference types nor value
types! They are handled in a special way...
That's not true. String is a reference type which overrides
operator==.
In what way do you believe they're not reference types?
As Richard explains:
They are immutable which results in some value like behavior but they are
definitely reference types.
Right. There's nothing particularly special about string being
immutable though - it's perfectly easy to write your own immutable
reference types, and it's often a good idea.
--
Jon Skeet - <sk***@pobox.co m> http://www.pobox.com/~skeet
If replying to the group, please do not mail me too This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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I've a really strange problem, in some part of my code I compare two
strings (through object), and while I *know* that they equal each
other, and in the watch window they do equal each other, then the
comparision return false.
See here for details:
http://www.ayende.com/Blog/PermaLink,guid,f5aa1a11-1710-434f-bfe0-39ac876a6acb.aspx
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--
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Visit Brain Trove ( http://www.BrainTrove.com )
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