Today's entry for the "kill it with fire" list

Gary Wheeler

bool flags[2];
//...
if ( (flags[0] == true) ||
(flags[1] == true) )
{
//...
if ( (flags[0] == TRUE) ||
(flags[1] == TRUE) )
{
}
}

X| I just found this in some code I have to extend to support a new feature. I wonder if Mike Rowe[^] knows C++...

Software Zen: delete this;

phil o

One can never be too sure :)

noop()

raddevus

Check them in the outer...then checks them in the inner??? :wtf:

Sheer Poetry

He's checkin' his flags, he's checkin' them twice. He knows if them flags have been naughty or nice!

Gary Wheeler

Yes, and the flags aren't changed anywhere inside the intervening 'logic'. Not only does he compare a bool to true, he also compares it to the Windows-defined TRUE as well, which is not really the same thing.

Software Zen: delete this;

Ron Anders

:-D

Bernhard Hiller

Oh no, that can be not only valid, but also necessary... Can you be sure that there's not some strange #define somewhere changing the meaning of TRUE or true? And when the flags array is a member of the class (instead of locally declared in a function), its values can be changed from where ever in a different thread. Just make sure you cope with such threats. :-D

Oh sanctissimi Wilhelmus, Theodorus, et Fredericus!

Gary Wheeler

Bernhard Hiller wrote:

#define somewhere changing the meaning of TRUE or true?

Even more reason to break out the flamethrower... :laugh:

Software Zen: delete this;

DJ van Wyk

What if, 15 years down the line, someone inserts code between the two different checks that changes the value of TRUE? You have to make absolutely sure that it is still true when the really important piece of code hits. I suggest you add a few inline ifs so that there will never be any doubt.

My plan is to live forever ... so far so good

Member 9167057

Hey, I recently removed code toying with the global BoolStr variable because some table-internal-to-the-program had to use yes/no instead of true/false which as easily readable but doesn't require meddling with globals.

englebart

just add this code before the first if statement:

if (flags[0] == TRUE) flags[0] = true;
if (flags[1] == TRUE) flags[1] = true;
if (flags[0] == FALSE) flags[0] = false;
if (flags[1] == FALSE) flags[1] = false;

Then you can trust !(not), && and || for the rest of the checks. Or better yet, with 2 Booleans, there are only four possible states, so normalize and then turn it into a switch statement with 0-3.

if (flags\[0\] == TRUE) flags\[0\] = true;
if (flags\[1\] == TRUE) flags\[1\] = true;
if (flags\[0\] == FALSE) flags\[0\] = false;
if (flags\[1\] == FALSE) flags\[1\] = false;
int state;
if (flags\[0\]) 
    state = 1
else 
    state = 0;
if (flags\[1\]) state += 2;
switch (state) {case 0-3:...}

Gary Wheeler

My gastrointestinal tract just inverted itself... X|

Software Zen: delete this;

Paulo_JCG

Is it possible we're talking about Quantum bool ????

Paulo Gomes Measuring programming progress by lines of code is like measuring aircraft building progress by weight. —Bill Gates Everything should be made as simple as possible, but not simpler. —Albert Einstein

Gary Wheeler

Only this[^] knows.

Software Zen: delete this;

S Mercurio

Maybe it's an existential program looking for the meaning of truth and it couldn't get a hold of Stephen Colbert.

englebart

Even worse: If the //... code that initializes the flags array really assigns those values into it, then it looks like the original code does not even consider these cases: x == true && y == TRUE. 2 variables with 4 possible values each means there should be 16 possible states. Normalizing the values reduces it to 2 variables with 2 possible values which gives 4 states. If true vs TRUE produce different outcomes, then God bless you and convert the "bools" into an enum. Consider creating a multidimensional array where the indexes are your "flags" and you initialize each array element to be the correct answer for that combination of states.

DSewhuk

might get corrupted to equal, say 42. Code that didn't explicitly check consistently for "==true" would take the wrong path. if(flags[x]) would be true, if(flags[x]==true) would be false. Then you also get the VB true, which is -1!

Nathan Minier

To quote my "favorite comment":

#define TRUE FALSE
//Happy debugging suckers

"Never attribute to malice that which can be explained by stupidity." - Hanlon's Razor

Super Lloyd

what if var TRUE = false; hey!? I betcha didn't think of it, did ya?! :omg: ;P

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Gary Wheeler

This is C++, fortunately.

Software Zen: delete this;

Super Lloyd

well, you know #undef TRUE #define TRUE 0

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