Bug of the day

[gervacleto]

Me too. I didn't see the semicolon until I review it two or three times. So maybe it is not a trap but a genuine bug. Some times you check your code 10 times and do not see this kind of bugs. :-\

You may forget having good days, just because you are remembering the past or thinking too much about the future. Live now and enjoy the moment!!

[Fabio Franco]

Tell me about it. I'm specially vulnerable to problems that are right in front of my face. I do this too often: :doh: Maybe it's my short span of attention.

To alcohol! The cause of, and solution to, all of life's problems - Homer Simpson ---- Our heads are round so our thoughts can change direction - Francis Picabia

[gervacleto]

This errors can be present in C like language. The last only in C# This one is usual (very)

if(Something)
One();
two();
...

Of course only One() is inside the if(), but it seems that the other two instructions are inside also. I did fall in this bug many times until I decided to enclose into curly braces any if() or loop with one or more instructions. It could increase the number of lines, but, for sure, decrease the bugs. Other one:

bool MyBoolValue = true;

if(MyBoolValue = false){
... SomeStuff ...
}

Maybe the compiler throws a warning, but this statement is valid. Surely is not what you want to do because you have omitted one equal sign:

if(MyBoolValue == false)...

I have no solution to this one, but to check again :sigh: Of course the comparison is not necessary, because MyBoolValue is true or false per se. ;)

if(MyBoolValue)...

for(int i = 0; i < MyArray.GetUpperBound(0); i++){
SomeStuff....
}

You must remember that GetUpperBound(0) does not start in '0' but in '1', because is the number of elements not the dimensions of the array so it must be:

for(int i = 0; i <= MyArray.GetUpperBound(0); i++)

I will try to remember more "Mistakes" that are common for me, but for sure here are more qualified people to show you many more.

You may forget having good days, just because you are remembering the past or thinking too much about the future. Live now and enjoy the moment!!

[Pablo Aliskevicius]

I usually prefer:

if (42 == ComputeSomeThing(x)) {
//...
}

This one avoids the = against == pit. Another thing I do: my IDE is configured to show operators (like '(){};,+-=...') in color, so they are a bit harder to miss (like the original example). There are two other tools that can help with this: compiler warnings, and static code analysis. JM2B,

Pablo. "Accident: An inevitable occurrence due to the action of immutable natural laws." (Ambrose Bierce, circa 1899).

[Fabio Franco]

gervacleto wrote:

if(Something) One(); two(); ...

This can also happen in C#, but auto indent of Visual Studio makes you less likely to fall in this trap.

gervacleto wrote:

if(MyBoolValue = false){

This happened to me several times and the warning saved. I always pay attention to warnings.

gervacleto wrote:

if(MyBoolValue)

I do not consider this a bug, it is actualy a coding style. I do it myself.

gervacleto wrote:

for(int i = 0; i <= MyArray.GetUpperBound(0); i++)

Never used this construct, so I wouldn't know. But will keep my mind to it in case I run into this. Thanks!

To alcohol! The cause of, and solution to, all of life's problems - Homer Simpson ---- Our heads are round so our thoughts can change direction - Francis Picabia

[Lost User]

Quote:

If an if-statement occupies more than one line, it gets braced.

Maybe I'm naïve, but I thought everybody did that! :)

[Gary Wheeler]

I've worked with people who did this:

if condition
DoSomething();
else
{
DoOtherThing1();
DoOtherThing2();
}

or

if condition
{
DoSomething1();
DoSomething2();
}
else
DoOtherThing();

Both of which give me the creeping heebie-jeebies.

Software Zen: delete this;

[MainFrameMan_ALIVE_AND_WELL]

the semi-colon on the end of the conditional, the block will always execute. DoSomething is in its own little world and will always execute. C# will just raise a warning on the conditional but will not compile with the DoSomeThing becuse it is not a method or an assignment. But, what if it is not C# compiler, then there could be compilers that would allow this and it would be worthless code, i still use Crimson, NotePad, etc to write code. Either to many semi colons or not enough !!

[StatementTerminator]

Gary Wheeler wrote:

if condition then DoThing1(); DoThing2(); DoThing3(); MainStuff();

Yeah that's one of my all-time favorites. It usually starts out like:

if(_condition_) 
    DoThing1();

And then someone comes along later and adds DoThing2(), and the compiler silently chuckles to itself and lets the code do a lot of Thing2. Personally, I like to always use curly braces to block off code for that very reason, even if it's only one statement. If I see something like that with one statement, I'll add the braces so it's clear when someone comes along and changes it. Putting it all on one line works fine as well, but I like to always create a code block because it makes it easier to add statements later. And really, what's the point of keeping it on one line? But I know a lot of programmers have an irrational fear of vertical space :)

[RafagaX]

I bet that in DoSomeThing there is logic to handle the strange case when the if condition is not firing properly. :rolleyes:

CEO at: - Rafaga Systems - Para Facturas - Modern Components for the moment...

[StatementTerminator]

Pablo Aliskevicius wrote:

This one avoids the = against == pit.

LOL, that one kills me, because I'm constantly switching back and forth between C# and VB :((

[KP Lee]

anton_l wrote:

It seems that problem is in semicolon after "if" statement.

It seems that's the reason he posted it! :laugh:

[Lutoslaw]

Klaus-Werner Konrad wrote:

Wich compiler?

FTFY: Witch compiler Actually, in this case the C# produces three useless wormings: both for the "while(...);" (an empty statment), "x=y" (an assigment instead of a comparison) and the "*" (an "unsafe" code), does it?

Greetings - Jacek

[Thomas Daniels]

No, it doesn't. But that's just the bug: it doesn't compile! [EDIT] I'm sorry, I didn't see the semicolon after the if statement. That's the bug! :doh:

The quick red ProgramFOX jumps right over the Lazy<Dog>. My latest article: Understand how bitwise operators work (C# and VB.NET examples) My group: C# Programmers Group

[Klaus Werner Konrad]

Thanks for the correction. My example was - as a reply to the mention of C, of course a C code snippet, and is the full working function body for strcpy(). Of course, it's unsafe - but lightning fast :-)

[BobJanova]

They're not useless warnings, they're warning you that you did something unintended. Actually this wouldn't compile at all in C#, even with unsafe mode turned on, because the result type isn't boolean. It's a classic and well known piece of C code, and I think you only got a warning for the empty loop body (and if you did if(a = 3) by accident you were just screwed, hence writing if(3 == a) instead which is an error if you screw it up).

[BobJanova]

Just in case you didn't get the joke there, he's making a funny about the compiler being witchcraft. The word you meant to use is 'which'.

[Lutoslaw]

Right. :thumbsup:

Greetings - Jacek

[Adam David Hill]

Ooh, nasty! Couldn't see it at first.

Check out my latest article: Celerity: How it was all done. A complete how-to on our sensor-driven head-tracking virtual reality tunnel game in C#.

[Marc Clifton]

Delphi4ever wrote:

if(SomeThing == SomeOtherThing);

I remember years ago spending a few hours debugging why (in C++):

for (int i=0; i<10; i++);
DoSomething();

where DoSomething executed only once. I only had to learn that lesson once! :rolleyes: Marc

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