Re: Anyway of knowing whether a integer is odd or even

David Otton wrote: > > This is subjective of course, but... yes. "(x%2)" is the most common > way to derive odd and even numbers. Manuals and tutorials use it, > prime-sieves use it. Bit-masks aren't in common use outside systems > programming. > > The programmer that has to follow you 6 months down the line doesn't > care that you shaved a few clock cycles off by being clever... he does > care that you left him clean, easily readable code. Being clever by using a relatively common technique... Nefarious! > > MOD is also the more general solution - how would you change the code > to colour every nth line red? Change all of one line? It's not like we're re-writting 1000 lines of code here. > > (BTW, a quick test show that 1 billion (i&1) in a loop execute in 9 > seconds, while (i%2) execute in 12 seconds. C (not PHP), MSVC++6, > PIII800. Which means I gain 3 billionths of a second on each test if I > use the bitwise operator.) Okay, this is certainly more true now, with faster processors, more RAM, etc. But years ago, there was a difference. > >>And why wouldn't you want to get the most performance out of your code, >>regardless of the language, scripting or otherwise? Especially when it's a >>one or two character switch that makes the difference? > > Because programmer time is /vastly/ more valuable than machine time. > Do you remove comments from your scripts because parsing /* */ // > symbols soaks up CPU time? In PHP this might matter a bit (unless you use the Zend Encoder or Cache or something), but I'm traditionally a C and C++ guy, and after compilation comments don't mean much. > >>I doubt that PHP should be classified as a scripting language any more >>than Perl is. Scripting languages are usually used to glue different >>applications together, like a shell script that uses awk and sed or >>whatever. PHP can be used to build applications, so it's more than a >>scripting language. Interpreted language is more like it. > > "Scripting language" is a common-usage synonym for "interpreted > language", and has been for several years. ("Your search for scripting > language found 387 results on www.perl.com.") > > http://www.tuxedo.org/~esr/jargon/html/entry/Python.html > > Not that I don't agree with you... > > djo I've never liked that scripting term either. It makes it sound like bash or a DOS batch script or something. It's so misleading. Perl used to fit the moniker a bit more, before it got all big and started weighing in at 900 pounds. J