The Daily WTF: Curious Perversions in Information Technology

2005-08-29 Reply Admin

res2:
itsSeed also appears to be a global... shame shame!

itsSeed is a member field. Here's your clue: this->itsSeed = time(NULL);

2005-08-29 Reply Admin

This won't work for very small or very large values. Also, I don't believe it will work as expected for negative values.

aikimark · 2005-08-29 Reply Admin

The "if (theMin >= theMax)" check will fail to prevent negative values as long as this condition isn't true, so negative parameter values can still create an infinite loop condition.

The anonymous poster used incorrect parameter values for their example. They should have used theMin:=-15 and theMax:=0.

christoofar · 2005-08-29 Reply Admin

Anonymous:
> year or so after she left

Women and Computer Science don't mix! ;-)

I've noticed that females involved in Software Engineering seem to be better at QA and understanding business requirements than many men. Dont most business decisions and requirements mimic the same reasoning behind impulse buys and lust for designer shoes (without the sticker price)?

John Smallberries · 2005-08-29 Reply Admin

christoofar:
Anonymous:
> year or so after she left

Women and Computer Science don't mix! ;-)

I've noticed that females involved in Software Engineering seem to be better at QA and understanding business requirements than many men. Dont most business decisions and requirements mimic the same reasoning behind impulse buys and lust for designer shoes (without the sticker price)?

I've known many men who impulsively made decisions to go with the latest "designer" software...and those had one hell of a sticker price.

dubwai · 2005-08-29 Reply Admin

md2perpe:
Anonymous:

> year or so after she left

Women and Computer Science don't mix! ;-)

The world's first programmer: http://en.wikipedia.org/wiki/Ada_Lovelace

While I disagree with the women and CS don't mix thing, it's pretty clear from historical records that Ada Lovelace never did anything but write some papers on how great Babbages machine would be when complete. It's not clear that she had any meaningful understanding of the machine. In short, she is famous for saying 'seriously, I'm actually a genius.'

ammoQ · 2005-08-29 Reply Admin

aikimark:
The "if (theMin >= theMax)" check will fail to prevent negative values as long as this condition isn't true, so negative parameter values can still create an infinite loop condition.

The anonymous poster used incorrect parameter values for their example. They should have used theMin:=-15 and theMax:=0.

aRange = theMax - theMin;

=

aRange = 0 - (-15);

=

aRange = 15;

sorry, no infinite loop this time ;-)

2005-08-29 Reply Admin

> > year or so after she left

> Women and Computer Science don't mix! ;-)

Hey! :@

(Admittedly, I can't quite this preview thing to work, but I doubt that it's because I'm a woman. Seriously, this comment form sucks)

III · 2005-08-29 Reply Admin

itsSeed is a member field. Here's your clue: this->itsSeed = time(NULL);

i'm pretty sure static class members (aka globals) can be referenced via "this->". however, the naming convention leads me to believe that it's an instance variable.

the wtf about that is that an instance variable is being used to keep track of whether a global (i.e. the prng seed) has been initialized.

2005-08-29 Reply Admin

Perhaps adding an entry to: http://brilliant.urbanup.com

emptyset · 2005-08-29 Reply Admin

dubwai:
While I disagree with the women and CS don't mix thing, it's pretty clear from historical records that Ada Lovelace never did anything but write some papers on how great Babbages machine would be when complete. It's not clear that she had any meaningful understanding of the machine. In short, she is famous for saying 'seriously, I'm actually a genius.'

having gone to great lengths to obtain a copy of an out of print biography on ada lovelace [0], i'll say there is plenty of evidence to suggest she was quite capable of understanding the machine. you have to consider the times, as well. being a self-taught mathematical hobbyist wasn't a common thing for women to take up back then - that she did pursue that route, and made interesting observations about algorithms ahead of church-turing's time, says a lot. her life towards the end was kind of depressing: she became addicted to morphine after using it to treat an illness, which probably didn't do much for her abilities.

[0] http://www.amazon.com/exec/obidos/ASIN/0875185983/thegreatideafind/104-3701586-1679962

stevekj · 2005-08-29 Reply Admin

EsotericMoniker:
Yeah I never got why some people think 'theNumber' is superior to 'number' or 'itsValue' is better than 'value'. The place that produced this was rife with that sort of needless (and useless) decoration.

This is a general problem. "Number" and "Value" are pretty useless variable names to begin with. I ran across a variable today called "myThis", which combines two of my favourite naming WTFs in one: "my" and "this"! Both of these are, of course, as semantically bankrupt as "Number" and "Value", and putting them together doesn't help one bit. Might as well call it "yourThat" for all the good the variable name does me as I read the code.

(I've never really liked using "this" to mean "current object", any more than I like Microsoft's "my" naming convention for desktop entities. Both are more of a hindrance to clear and logical thought than a help, particularly in conversations, which start to resemble Who's On First pretty quickly.)

Proper variable naming is at least as important as proper commenting, and for the same reason: the compiler doesn't care about either one, but people reading the code sure do! A misnamed variable is just as bad as a misleading comment. Neither is worthy of the label "professional".

dubwai · 2005-08-29 Reply Admin

emptyset:

dubwai:
While I disagree with the women and CS don't mix thing, it's pretty clear from historical records that Ada Lovelace never did anything but write some papers on how great Babbages machine would be when complete. It's not clear that she had any meaningful understanding of the machine. In short, she is famous for saying 'seriously, I'm actually a genius.'

having gone to great lengths to obtain a copy of an out of print biography on ada lovelace [0], i'll say there is plenty of evidence to suggest she was quite capable of understanding the machine. you have to consider the times, as well. being a self-taught mathematical hobbyist wasn't a common thing for women to take up back then - that she did pursue that route, and made interesting observations about algorithms ahead of church-turing's time, says a lot. her life towards the end was kind of depressing: she became addicted to morphine after using it to treat an illness, which probably didn't do much for her abilities.

[0] http://www.amazon.com/exec/obidos/ASIN/0875185983/thegreatideafind/104-3701586-1679962

I basing my statements on a book written by a researcher who was involved with completing a working reproduction of the never finished machine (they had to make some changes to the design to make it actually do anything.) What he found from her writings and Babbage's was that Ada Lovelace had produced next to nothing towards the project.

If you have a links to reproductions of her work, I'd be open to other views. All I can find is that she was able to imagine the uses of computers way before her time. This makes her a great anticipator but not a programmer.

In all reality, though, the first programmers were women. 'Computer' used to be a job description. It's what female mathematicians did before the programmable computer. When ENIAC was created, the programmers were the people who were most familiar with the alogrithms: the female computers.

ammoQ · 2005-08-29 Reply Admin

stevekj:

This is a general problem. "Number" and "Value" are pretty useless variable names to begin with. I ran across a variable today called "myThis", which combines two of my favourite naming WTFs in one: "my" and "this"! Both of these are, of course, as semantically bankrupt as "Number" and "Value", and putting them together doesn't help one bit. Might as well call it "yourThat" for all the good the variable name does me as I read the code.

(I've never really liked using "this" to mean "current object", any more than I like Microsoft's "my" naming convention for desktop entities. Both are more of a hindrance to clear and logical thought than a help, particularly in conversations, which start to resemble Who's On First pretty quickly.)

Proper variable naming is at least as important as proper commenting, and for the same reason: the compiler doesn't care about either one, but people reading the code sure do! A misnamed variable is just as bad as a misleading comment. Neither is worthy of the label "professional".

Prefixes like "my" are an easy solution for a conflict with reserved names, especially when it comes to variable names like "value" or "number". Today I tried to compile a very old program, which had a function "pow" that conflicted with a built-in function of the compiler; so I changed it to "mypow".

dhromed · 2005-08-29 Reply Admin

Today I tried to compile a very old program, which had a function "pow" that conflicted with a built-in function of the compiler; so I changed it to "mypow".

When given the choice between a 'semantically bankrupt' (must remember that one) and a verbose name, I opt for the latter.

I'd have named the function 'raiseToPower' or 'raisePow'. 'mypow' immediately causes me to think oh you can do better than that.

dhromed · 2005-08-29 Reply Admin

*when I'm seriously working, of course. If I need to quickly sketch a snippet, I'd probably have called it 'mypow'. Or 'powpow'. Or 'poof'.

ammoQ · 2005-08-29 Reply Admin

dhromed:
Today I tried to compile a very old program, which had a function "pow" that conflicted with a built-in function of the compiler; so I changed it to "mypow".

When given the choice between a 'semantically bankrupt' (must remember that one) and a verbose name, I opt for the latter.

I'd have named the function 'raiseToPower' or 'raisePow'. 'mypow' immediately causes me to think oh you can do better than that.

Actually it was just curious if the compile (freepascal) was able to compile the program (Turbo pascal). I'm not even sure if the "pow" function in this program really meant "raiseToPower".
Even if so, if that was a serious program, I would have had to check if it makes sense to take it out and use the built-in function. Anyway, the prefix "my" is a good indicator for "likely reinvented the wheel".

brazzy · 2005-08-29 Reply Admin

stevekj:

This is a general problem. "Number" and "Value" are pretty useless variable names to begin with.

Well, that depends on the context. For example, in the implementation of a hash table (or any kind of lookup functionality),
"value" has a well-defined technical meaning.

dhromed · 2005-08-29 Reply Admin

The hungarian version of that is "asjf_".

dhromed · 2005-08-29 Reply Admin

Drat, threads knit fast around here.

My previous post in reply to:

Anyway, the prefix "my" is a good indicator for "likely reinvented the wheel".

2005-08-29 Reply Admin

III:
>itsSeed is a member field. Here's your clue: this->itsSeed = time(NULL); i'm pretty sure static class members (aka globals) can be referenced via "this->". however, the naming convention leads me to believe that it's an instance variable. the wtf about that is that an instance variable is being used to keep track of whether a global (i.e. the prng seed) has been initialized.

I'll be damned. You're right. The folowing compiles without warnings or errors in VC7. Certainly doesn't feel right, though...statics don't belong to the instance...I hate C++. I really do.

#include <IOSTREAM>
struct StaticTest
{
static long field;
void printField()
{
std::cout << this->field << std::endl;
}
};

long StaticTest::field = 1;

int _tmain(int argc, const char** argv )
{
StaticTest test;
test.printField();
return 0;
}

ammoQ · 2005-08-29 Reply Admin

IIRC java allows that, too.

2005-08-29 Reply Admin

EsotericMoniker:
Yeah I never got why some people think 'theNumber' is superior to 'number' or 'itsValue' is better than 'value'. The place that produced this was rife with that sort of needless (and useless) decoration.

"number" and "value" might be keywords. Easier just to add letters rather than RTFM or hit Compile.

More likely, the author is saying all the statements in his or her mind as she writes them and finds something closer to proper english easier to work with.

mizhi · 2005-08-29 Reply Admin

christoofar:
Anonymous:
> year or so after she left

Women and Computer Science don't mix! ;-)

I've noticed that females involved in Software Engineering seem to be better at QA and understanding business requirements than many men. Dont most business decisions and requirements mimic the same reasoning behind impulse buys and lust for designer shoes (without the sticker price)?

And men wonder why women in technical fields say they have to deal with a ton of sexism.

Mike R · 2005-08-30 Reply Admin

dhromed:
Today I tried to compile a very old program, which had a function "pow" that conflicted with a built-in function of the compiler; so I changed it to "mypow".

When given the choice between a 'semantically bankrupt' (must remember that one) and a verbose name, I opt for the latter.

I'd have named the function 'raiseToPower' or 'raisePow'. 'mypow' immediately causes me to think oh you can do better than that.

Namespace means nothing.

I would have figured out what the function did, determined if it was developed by NIH syndrom, if so, use the already invented (and likely adequately debugged function) and dumped the dupe. Or, if It didn't suffer from NIH, and was a novel function, I would have given it a more descriptive name like:

MakePowSound, PreviousOctalWord, PushOtherWorld, PressOrangeWidget, etc.. (note these names depend on functionality)

or if my "Function to raise a number to a power" were a superefficient über-function, then I'd use hungarian notation and name it ufihPow.

brazzy · 2005-08-30 Reply Admin

ammoQ:
IIRC java allows that, too.

If you're talking about static fields being accessible through an instance, yes.

The unanimous opinion of comp.lang.java.programmer is that it's one of the language designers' biggest mistakes.

2005-08-30 Reply Admin

mizhi:
christoofar:
Anonymous:
> year or so after she left

Women and Computer Science don't mix! ;-)

I've noticed that females involved in Software Engineering seem to be better at QA and understanding business requirements than many men. Dont most business decisions and requirements mimic the same reasoning behind impulse buys and lust for designer shoes (without the sticker price)?

And men wonder why women in technical fields say they have to deal with a ton of sexism.

Wordy McFucking Word, as one of my good friends would say.

Personally, I've not experienced too much in the way of ignorant sexism in my professional life. Online, in fora like this one, is a whole different kettle of fish. It's quite pathetic and it's one of the reasons I've not posted here before, even though I've been a regular reader for a while.

Vicky

mizhi · 2005-08-30 Reply Admin

Anonymous:
mizhi:

And men wonder why women in technical fields say they have to deal with a ton of sexism.

Wordy McFucking Word, as one of my good friends would say.

Personally, I've not experienced too much in the way of ignorant sexism in my professional life. Online, in fora like this one, is a whole different kettle of fish. It's quite pathetic and it's one of the reasons I've not posted here before, even though I've been a regular reader for a while.

Anonymity gives people the balls to say things they would not otherwise say aloud.

emptyset · 2005-08-30 Reply Admin

Anonymous:

Wordy McFucking Word, as one of my good friends would say.

are you from the midwest?

Anonymous:

Personally, I've not experienced too much in the way of ignorant sexism in my professional life. Online, in fora like this one, is a whole different kettle of fish. It's quite pathetic and it's one of the reasons I've not posted here before, even though I've been a regular reader for a while.

that's good news. at my old workplace, i was told (by a female coworker) that women never got promoted. things like that can occur, but most of the harsh rules in place are a deterrent towards sexist attitudes. ah, that reminds me (classic):

Ian: Ah, shit. They are not gonna release the album...because they have decided that the cover is sexist.
Nigel: Well so what? What's wrong with being sexy? I mean there's no....
Ian: Sex-ist.
David: -ist, not sexy.

Vicky · 2005-08-30 Reply Admin

mizhi:
Anonymous:
mizhi:

And men wonder why women in technical fields say they have to deal with a ton of sexism.

Wordy McFucking Word, as one of my good friends would say.

Personally, I've not experienced too much in the way of ignorant sexism in my professional life. Online, in fora like this one, is a whole different kettle of fish. It's quite pathetic and it's one of the reasons I've not posted here before, even though I've been a regular reader for a while.

Anonymity gives people the balls to say things they would not otherwise say aloud.

Shrug. My main reason for not registering before was lack of time, rather than a desire for anonymity, but I've registered now, does that help? I'm not putting my email address up in my public profile if that's what you're getting at: I've done that before and ended up receiving all sorts of delightful things in my inbox.

Vicky

Vicky · 2005-08-30 Reply Admin

emptyset:
Anonymous:

Wordy McFucking Word, as one of my good friends would say.

are you from the midwest?

Nope, I'm in the UK. And my friend who says that a lot is Canadian!

Vicky

Vicky · 2005-08-30 Reply Admin

Vicky:
mizhi:
Anonymous:
mizhi:

And men wonder why women in technical fields say they have to deal with a ton of sexism.

Wordy McFucking Word, as one of my good friends would say.

Personally, I've not experienced too much in the way of ignorant sexism in my professional life. Online, in fora like this one, is a whole different kettle of fish. It's quite pathetic and it's one of the reasons I've not posted here before, even though I've been a regular reader for a while.

Anonymity gives people the balls to say things they would not otherwise say aloud.

Shrug. My main reason for not registering before was lack of time, rather than a desire for anonymity, but I've registered now, does that help? I'm not putting my email address up in my public profile if that's what you're getting at: I've done that before and ended up receiving all sorts of delightful things in my inbox.

Vicky

OK, I just realised that you might have been referring to the people who made the ignorant remarks in the first place, rather than me. If that's the case I apologise for snapping!

Vicky

mizhi · 2005-08-30 Reply Admin

Vicky:

Shrug. My main reason for not registering before was lack of time, rather than a desire for anonymity, but I've registered now, does that help? I'm not putting my email address up in my public profile if that's what you're getting at: I've done that before and ended up receiving all sorts of delightful things in my inbox.

Actually, I wasn't referring specifically to you. To people on the net in general. Even if a person is "registered" on a website, they might as well be a talent sea otter for all one can verify. [:)]

mizhi · 2005-08-30 Reply Admin

Vicky:

OK, I just realised that you might have been referring to the people who made the ignorant remarks in the first place, rather than me. If that's the case I apologise for snapping!

I've had more caustic things said to me over a misplaced period. No worries. [:)]

BigBoote66 · 2005-08-30 Reply Admin

Hi, this is the submitter of this WTF.

Just felt I'd clear up a few things:

1. You can't blame the naming convention (its/a/an/the) on The Genius, it was a naming convention long established by our organization and now followed for consistency. It's not the worst thing in the world, and, as others have pointed out, it does conveniently prevent a lot of name overloading problems with libraries & such.

2. We were mistaken about the crash opportunity - we assumed division by zero would result in an exception, but it does return Inf, even on Solaris. As if that were the least of the problems in this function.

3. In scanning the posts, it seems like everyone here has hit the high points of this particular function. I have to admit that the "reciprocal technique" of generating a random double was always my favorite part.

4. I've always compared this function to the quote by some famous sculptor (sorry, can't remember who) about how to carve an elephant: "Start with a rock, then chip away everything that doesn't look like an elephant."

4. Yes, she was a Mensa member.

-BbT

BigBoote66 · 2005-08-30 Reply Admin

One more thing - her name wasn't Paula Bean.

-BbT

Mike R · 2005-08-30 Reply Admin

BigBoote66:
Hi, this is the submitter of this WTF.

Just felt I'd clear up a few things:

Sure, this late in the game clarification is everything

1. You can't blame the naming convention (its/a/an/the) on The Genius, it was a naming convention long established by our organization and now followed for consistency. It's not the worst thing in the world, and, as others have pointed out, it does conveniently prevent a lot of name overloading problems with libraries & such.

If I were to work at an organisation that insisted upon unruly and useless warts as a naming convention, my resume would be posted everywhere. Hell, I'd even consider relocating to Elbonia. I can understand standardising on prefixing the name with its type, I can understand prefixing it with its scope, I can understand prefixing it like microsoft does in it's SDK, but I simply cannot fathom the stupidity of prefixing everything with the and its. itsIdiotic.

2. We were mistaken about the crash opportunity - we assumed division by zero would result in an exception, but it does return Inf, even on Solaris. As if that were the least of the problems in this function.

Depends on whether the hardware has that exception masked out (Floating-point divide by zero) it can be enabled, and at that point will be a crash opportunity. IIRC, there's a way to turn the exception on and off in the C standard library.

3. In scanning the posts, it seems like everyone here has hit the high points of this particular function. I have to admit that the "reciprocal technique" of generating a random double was always my favorite part.

Yep, when so many other techniques are totally obvious.

4. I've always compared this function to the quote by some famous sculptor (sorry, can't remember who) about how to carve an elephant: "Start with a rock, then chip away everything that doesn't look like an elephant."

More like throw spaghetti against the wall to see what sticks... seriously.

4. Yes, she was a Mensa member.

Good reason to never join Mensa.

Omnifarious · 2005-08-30 Reply Admin

Mike R:
And on a more serious note:

Where does this "genius" get off calling this thing a random number generator,

This whole train-wreck of a function could be summed as follows:

return rand()*(iMax-iMin)+iMin

No, that would be better than the function written because it would actually stand a chance of having an even distribution. This function doesn't have a prayer.

2005-08-30 Reply Admin

Anonymous:
This truely is a random function!, when run, it does something completely random; it either crash (divide by 0) [...]

No, it should ( C ) throw the double to an +inf value, from which the infinite loop would occur, since (+Inf - N --> +Inf) IIRC for double & floats.

I expect this was the source of the 100% CPU, and not a very very very small range.

-dave-

BigBoote66 · 2005-09-01 Reply Admin

Mike R:
If I were to work at an organisation that insisted upon unruly and useless warts as a naming convention, my resume would be posted everywhere. Hell, I'd even consider relocating to Elbonia. I can understand standardising on prefixing the name with its type, I can understand prefixing it with its scope, I can understand prefixing it like microsoft does in it's SDK, but I simply cannot fathom the stupidity of prefixing everything with the and its. itsIdiotic.

You probably missed some of the commentary above - the naming convention is scope based:

a/an - local variable
the - parameter
its - member data

I'm not sure what our convention is for globals, as I've never seen them in the code. The convention itself was inherited from the commercial product XVT (a cross-platform GUI library), which seemed as good as any to use by the original designers of the system, as it used XVT for many of its clients.

I can only dream of the programmer's paradise you must live in if following an odd but non-horrible naming convention is sufficient to drive you to looking for other employment.

-BbT

Maurits · 2005-09-01 Reply Admin

BigBoote66:
I'm not sure what our convention is for globals

TheOneAndOnly

2005-09-01 Reply Admin

Xepol:
You know, it might be time to make a serious effort to start getting "Brillant" entered in the wikis out there (encyclopedias, dictionaries - is there one?) Then the rest of the world would understand us when we use it in reference to stuff like this. And it makes such a great pejorative, we should share it with the world!

Actually it means "bright" or "shining" in French.

stevekj · 2005-09-07 Reply Admin

BigBoote66:

4. Yes, she was a Mensa member.

Good reason to never join Mensa.

Well, anyone who's studied high-IQ societies at all will immediately realize a few things:

1) IQ is difficult to measure accurately, sort of like programmer productivity - take it with a fair amount of salt;

2) Mensa contains a disproportionate number of people who like to brag about their intelligence, but who don't necessarily actually have a whole lot of it (at a 98th percentile cutoff, it means that if you can get through high school without cheating, you can probably join); and

3) There are lots of high-IQ societies above Mensa, most of which contain much lower proportions of braggarts.

I believe it was Groucho Marx who said "I would never join a club that would have me as a member".

2005-11-13 Reply Admin

Anonymous:
Mike R:
Mike R:
And on a more serious note:

Where does this "genius" get off calling this thing a random number generator,

This whole train-wreck of a function could be summed as follows:

return rand()*(iMax-iMin)+iMin

[:$] Heh.. replace rand with (float(rand())/float(RAND_MAX))

Thank you, I don't know why people are so terrified of a using little arithmetic now and then.

It seems that neither of the above posters used a little arithmetic either :)

That function doesn't even come close to generating a value from iMin to iMax. If you had iMin = 2 and iMax = 10 you'd be producing something from 2 to (RAND_MAX * 8), which is nothing close to a value between 2 and 8!

The real WTF here is how many people like to dump on other people when they themselves are clueless!

If you wanted to produce a psuedo-random value from A - B you'd do something like:

value = rand()% (iMax - iMin) + iMin; // The simple way that most average programmers would use.

Or better (to use the avoid only masking on the lower bits of the number generated):

double value = (double) rand()/ (double) ( (RAND_MAX + 1)/iMax ) ;

Mike R · 2005-11-15 Reply Admin

Anonymous:
Anonymous:
Mike R:
Mike R:
And on a more serious note:

Where does this "genius" get off calling this thing a random number generator,

This whole train-wreck of a function could be summed as follows:

return rand()*(iMax-iMin)+iMin

[:$] Heh.. replace rand with (float(rand())/float(RAND_MAX))

Thank you, I don't know why people are so terrified of a using little arithmetic now and then.

It seems that neither of the above posters used a little arithmetic either :)

That function doesn't even come close to generating a value from iMin to iMax. If you had iMin = 2 and iMax = 10 you'd be producing something from 2 to (RAND_MAX * 8), which is nothing close to a value between 2 and 8!

The real WTF here is how many people like to dump on other people when they themselves are clueless!

If you wanted to produce a psuedo-random value from A - B you'd do something like:

value = rand()% (iMax - iMin) + iMin; // The simple way that most average programmers would use.

Or better (to use the avoid only masking on the lower bits of the number generated):

double value = (double) rand()/ (double) ( (RAND_MAX + 1)/iMax ) ;

Are you dumb or just stupid?

The real WTF here is that you're even more clueless.

Here is my code, which I posted as an example. Quoted above. Please notice I said the rand() call needed to be replaced with a bit of code to normalise the number to the range from 0 to 1. I was hasty in my first reply and realised the mistake, and since the forum doesn't allow editing, I simply replied with the correction in the post.



int iMin = 5;

int iMax = 10;



float GetRand()

{

    return  (float(rand())/float(RAND_MAX))*(iMax-iMin)+iMin;

}



int main()

{

    printf("A listing of random numbers from %i through %i:\n\n", iMin, iMax);

    for(int n = 0; n < 100; n++)

    {

        printf("GetRand returns %f\n", GetRand());

    }

    return 0;

}

which outputs:



A listing of random numbers from 5 through 10:



GetRand returns 5.006256

GetRand returns 7.817927

GetRand returns 5.966521

GetRand returns 9.043703

GetRand returns 7.925047

GetRand returns 7.399365

GetRand returns 6.751457

GetRand returns 9.479812

GetRand returns 9.114200

GetRand returns 8.733024

GetRand returns 5.870540

GetRand returns 9.294717

GetRand returns 8.552507

GetRand returns 7.567675

GetRand returns 6.519974

GetRand returns 5.074923

GetRand returns 5.457015

GetRand returns 6.822260

GetRand returns 5.736564

GetRand returns 5.829493

GetRand returns 9.942625

GetRand returns 7.228462

GetRand returns 5.595416

GetRand returns 5.023347

GetRand returns 5.044557

GetRand returns 6.889401

GetRand returns 7.658315

GetRand returns 7.855922

GetRand returns 8.008820

GetRand returns 8.035829

GetRand returns 5.831172

GetRand returns 8.315226

GetRand returns 7.253945

GetRand returns 6.760613

GetRand returns 5.285195

GetRand returns 8.038423

GetRand returns 8.916593

GetRand returns 9.013031

GetRand returns 7.599414

GetRand returns 6.509751

GetRand returns 9.379864

GetRand returns 8.633381

GetRand returns 9.779504

GetRand returns 9.628590

GetRand returns 7.696768

GetRand returns 5.711692

GetRand returns 7.310404

GetRand returns 6.176641

GetRand returns 9.311197

GetRand returns 6.048006

GetRand returns 8.898282

GetRand returns 9.218268

GetRand returns 9.983978

GetRand returns 9.998474

GetRand returns 8.057497

GetRand returns 6.962188

GetRand returns 6.331065

GetRand returns 6.486404

GetRand returns 9.200720

GetRand returns 5.118717

GetRand returns 6.879330

GetRand returns 5.463118

GetRand returns 8.386029

GetRand returns 5.281075

GetRand returns 5.043947

GetRand returns 9.593951

GetRand returns 6.379437

GetRand returns 6.364483

GetRand returns 7.939543

GetRand returns 8.455916

GetRand returns 9.188055

GetRand returns 8.632466

GetRand returns 7.424696

GetRand returns 6.026795

GetRand returns 8.718680

GetRand returns 7.342296

GetRand returns 7.289804

GetRand returns 9.745781

GetRand returns 8.722190

GetRand returns 5.541398

GetRand returns 7.995239

GetRand returns 6.926176

GetRand returns 8.675039

GetRand returns 8.044832

GetRand returns 7.862026

GetRand returns 6.806696

GetRand returns 5.757775

GetRand returns 6.125523

GetRand returns 7.125767

GetRand returns 9.014405

GetRand returns 7.585528

GetRand returns 9.949950

GetRand returns 8.757744

GetRand returns 6.727805

GetRand returns 5.844905

GetRand returns 8.286538

GetRand returns 7.459487

GetRand returns 5.317698

GetRand returns 8.498795

GetRand returns 7.524033

Press any key to continue

Hmm.... Numbers from 5-10. Gee, Who'da thunk.



A listing of random numbers from 5 through 10:



GetRand returns 0.012515

GetRand returns 5.637057

GetRand returns 1.933455

GetRand returns 8.089133

GetRand returns 5.851343

GetRand returns 4.799756

GetRand returns 3.503663

GetRand returns 8.961538

GetRand returns 8.230159

GetRand returns 7.467643

GetRand returns 1.741453

GetRand returns 8.591270

GetRand returns 7.106532

GetRand returns 5.136447

GetRand returns 3.040598

GetRand returns 0.149878

GetRand returns 0.914225

GetRand returns 3.645299

GetRand returns 1.473443

GetRand returns 1.659341

GetRand returns 9.887363

GetRand returns 4.457875

GetRand returns 1.191087

GetRand returns 0.046703

GetRand returns 0.089133

GetRand returns 3.779609

GetRand returns 5.317766

GetRand returns 5.713065

GetRand returns 6.018926

GetRand returns 6.072955

GetRand returns 1.662698

GetRand returns 6.631868

GetRand returns 4.508852

GetRand returns 3.521978

GetRand returns 0.570513

GetRand returns 6.078144

GetRand returns 7.834860

GetRand returns 8.027778

GetRand returns 5.199939

GetRand returns 3.020147

GetRand returns 8.761600

GetRand returns 7.268315

GetRand returns 9.561050

GetRand returns 9.259158

GetRand returns 5.394689

GetRand returns 1.423687

GetRand returns 4.621795

GetRand returns 2.353785

GetRand returns 8.624237

GetRand returns 2.096459

GetRand returns 7.798230

GetRand returns 8.438339

GetRand returns 9.970085

GetRand returns 9.999084

GetRand returns 6.116300

GetRand returns 3.925214

GetRand returns 2.662698

GetRand returns 2.973443

GetRand returns 8.403236

GetRand returns 0.237485

GetRand returns 3.759463

GetRand returns 0.926435

GetRand returns 6.773504

GetRand returns 0.562271

GetRand returns 0.087912

GetRand returns 9.189866

GetRand returns 2.759463

GetRand returns 2.729548

GetRand returns 5.880342

GetRand returns 6.913309

GetRand returns 8.377900

GetRand returns 7.266484

GetRand returns 4.850427

GetRand returns 2.054029

GetRand returns 7.438950

GetRand returns 4.685592

GetRand returns 4.580586

GetRand returns 9.493590

GetRand returns 7.445971

GetRand returns 1.083028

GetRand returns 5.991758

GetRand returns 3.853175

GetRand returns 7.351648

GetRand returns 6.090965

GetRand returns 5.725275

GetRand returns 3.614164

GetRand returns 1.515873

GetRand returns 2.251526

GetRand returns 4.252442

GetRand returns 8.030525

GetRand returns 5.172161

GetRand returns 9.902015

GetRand returns 7.517094

GetRand returns 3.456349

GetRand returns 1.690171

GetRand returns 6.574481

GetRand returns 4.920024

GetRand returns 0.635531

GetRand returns 6.999084

GetRand returns 5.049145

Press any key to continue

Gee, your second function is a stellar example of fitting the specs. Returns numbers from 0 through 10.

Mike "The real WTF here is bagging on someone for being clueless, when you yourself are clueless" R

2006-04-03 Reply Admin

Th code is fairly bad, but I don't think that the infinite loop comes from
where most people are expecting it.

	> for (; aRange <= aValue; aValue -= aRange);

In floating point maths, there is a concept known as Epsilon (e); such that
epsilon is the smallestnumber for which x+e != x.(I hope the Epsilon comes out right - it is a greek "e" and looks like a squiggly, 
back to front 3)

Now for a 65-bit IEEE double, epsilon is (very) approximately x/1.0e16

i.e. for "aValue -= aRange" to have no effect on aValue, aRange must be
less than aValue/1.0e16.  Therefore, aRange must be less than aValue, so 
the for loop will exit immediately.
So how do we get the infinite loop?

I think it comes from the code:
	double aValue = (double)anIntegerPortion + 1.0/(double)aFractionPortion;

In IEEE floating point maths, division by zero doesn't (normally) crash 
the program.  It returns some sort of pseudo-number like NaN (Not a Number).

NaN minus anything (or plus, times or divided by anything) = NaN.
Also, x<NaN is always false (as is x==NaN, x>NaN etc).

So I think our hero has struk the 1 in 32000 case of FractionPortion==0, 
thus generating a NaN and hence an infinite loop.
Isn't FP maths fun?  :)

2006-04-04 Reply Admin

Anonymous:

It seems that neither of the above posters used a little arithmetic either :)
...
double value = (double) rand()/ (double) ( (RAND_MAX + 1)/iMax ) ;

Well, sure, just guess what random numbers you'll get with that refined implementation on implementations where RAND_MAX == INT_MAX.

2006-04-05 Reply Admin

mizhi:

And men wonder why women in technical fields say they have to deal with a ton of sexism.

Oddly, I haven't had to deal with sexism. I did have one interview where they warned me that many of the clients wouldn't think I was capable (car dealerships), but I didn't take the job -- the offered salary sucked. At my current job (gov't contractor) women get promoted at the same rate as men, and while men do outnumber us ladies, we are treated uniformly.

And I can attest that at least here, women perform uniformly as well. I've had the pleasure of working with some very dedicated, talented, and experienced female engineers, none of whom would want anything to do with this monstrous piece of code -- except to perhaps mount it on the wall of their cubicles to laugh at.

2006-04-07 Reply Admin

CalliArcale wrote:
> mizhi wrote:

> And men wonder why women in technical fields say they have to deal with a ton of sexism.

> Oddly, I haven't had to deal with sexism.

It has always struck me as self-destructive to accept or reject somebody on sex/race/religious grounds.
In a previous life, I was responsible for hiring programmers. I always figured that if I didn't hire the
best person, I was short-changing my ability to compete in the market. The competent person who
I just rejected would probably go and work for the opposition, and I'd be left with a second-rate
replacement.

Other than ability and potential, the only other criteria I considered was "would they fit into the team?".
I occasionally rejected somebody who's attitude was bad and who I thought would disrupt the team.

I repeatedly hear stories of employers who won't hire women, or people of a particular race or religion.
I've even been on the wrong end of that. Last time I was job hunting, I spoke to a number of people
who wouldn't consider me as I was too old (forty-something).

Such is life.

2007-01-19 Reply Admin

If min and max are < 0 and min < max then the for loop never terminates because:

counter -= min

but min is negative, so counter gets larger and will never be "less than" anything.

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