The Magician's String, what you see is not what you get.

[Nicolas Dorier]

static void Main(string[] args)
{
String str1 = "http://toto.com/";
String str2 = "http://toto.com‏/";
bool eq = str1 == str2;
Console.WriteLine(eq); //print false

str1 = "http://toto.com/";
str2 = "http://toto.com/";
eq = str1 == str2;
Console.WriteLine(eq); //print true

}

See for yourself, but copy the code, do not retype it. :) I lost hair on this one, bug on an actual project for one customer. But it is a nice trick to do to one of your most hated co worker if his computer is unlocked... Also works in configuration files. ;) This is pure evil though. [UPDATE] With some advice I found even more evil than that.

"а" == "a" //false

[Brisingr Aerowing]

Wow. That is evil! :evil_grin:

What do you get when you cross a joke with a rhetorical question?

[PIEBALDconsult]

Use better tools.

C:\>copy con x.cs
static void Main(string[] args)
{
String str1 = "http://toto.com/";
String str2 = "http://toto.com?/";
bool eq = str1 == str2;
Console.WriteLine(eq); //print false

    str1 = "http://toto.com/";
    str2 = "http://toto.com/";
    eq = str1 == str2;
    Console.WriteLine(eq); //print true

}^Z
1 file(s) copied.

P.S. This also reminds me of the time I helped a fellow student track down an error that turned out to be caused by a TAB where a sequence of SPACEs was expected.

[Guirec]

Have been reading this from right to left and left to right but could not see anything wrong with the code :-) Ca marche bien avec tutu et tata aussi!!!

[Nicolas Dorier]

Ironnically, the best tool that can show it to you is command line. Even notepad would not show. EDIT : TextPad seems to work

[Dave Kreskowiak]

Ohhhh that's evil! I love it! :laugh:

A guide to posting questions on CodeProject

Click this: Asking questions is a skill. Seriously, do it.
Dave Kreskowiak

[PIEBALDconsult]

Notepad will, with the correct typeface -- try Terminal.

[Nicolas Dorier]

I tried to change font, and encoding, nothing do. I even tried to copy the string in the command line, and don't get the ?. How did you do ?

[PIEBALDconsult]

On the command line I use "Raster fonts" 7x12. (Win 7)

[Nicolas Dorier]

I also have, I think the problem is that I am using "clink" as my command line program. However, on powershell, I get the missing char ! But Notepad, would not show me anything.

[PIEBALDconsult]

I expect it has to be a non-truetype typeface. I also see it with "Nifty Terminal".

[Nicolas Dorier]

Yes you are right on Terminal. It definitively shows me, I was trying other fonts. ;) Need to train myself about what font, truetype, and typeface means :)

[Xmen Real]

:thumbsup::thumbsup::thumbsup:

TVMU^P[[IGIOQHG^JSH`A#@`RFJ\c^JPL>;"[,*/|+&WLEZGc`AFXc!L %^]*IRXD#@GKCQ`R\^SF_WcHbORY87֦ʻ6ϣN8ȤBcRAV\Z^&SU~%CSWQ@#2 W_AD`EPABIKRDFVS)EVLQK)JKQUFK[M`UKs*$GwU#QDXBER@CBN% R0~53%eYrd8mt^7Z6]iTF+(EWfJ9zaK-i’TV.C\y<pŠjxsg-b$f4ia>

----------------------------------------------- 128 bit encrypted signature, crack if you can

[Rage]

So, for us mortals, care to explain what is going on here ?

~RaGE();

I think words like 'destiny' are a way of trying to find order where none exists. - Christian Graus Entropy isn't what it used to.

[Nicolas Dorier]

Magic. :) str2 is a string with an hidden character. If you copy my code, you copy the hidden character, so this bug follow you in whatever programming language. You can execute the code in debug mode, and see that str2 is length +1 str1. However, I have no idea how I ended up with this hidden character in my code. (the int value of this strange character is 0x200f)

[Wonde Tadesse]

Compileonline.com[^] will shows you the buggy char on String str2 . Interesting though. :)

Wonde Tadesse

[Nicolas Dorier]

did not know this tool ! good to know.

[Nicholas Marty]

Another thing that bit me before was an UTF-8 preamble or BOM with the bytes 0xEF, 0xBB, 0xBF that got copied from somewhere... :doh:

[Nicolas Dorier]

Already got it, if you create a text file with visual studio, it bites you.

[Freak30]

I once read a kind of ironic posting about what you could do to obscrure your code (and this way make yourself irreplacable). One of the topics was using similar letters from different alphabets in variable names. They used the example of the Cyrillic 'a' which looks just like the Latin 'a' but is seen as different by the compiler. I assume you could have reached a similar effect by using a Cyrillic 'r' instead of the Latin 'p' in the URL. :-D

The good thing about pessimism is, that you are always either right or pleasently surprised.