Quadratic

Path: csiph.com!eternal-september.org!feeder.eternal-september.org!mx02.eternal-september.org!.POSTED!not-for-mail From: Matthew Carter Newsgroups: comp.lang.php Subject: Re: test prog inpu tpost Date: Fri, 01 Jan 2016 21:40:09 -0500 Organization: Ahungry (http://ahungry.com) Lines: 140 Message-ID: <87fuygd7qu.fsf@ahungry.com> References:

<5686B656.3040603@arnowelzel.de> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: mx02.eternal-september.org; posting-host="7c986cd4736462de309a749b207746fe"; logging-data="20786"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+8+hN2Wl4EdwXwmA6iZKNV" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) Cancel-Lock: sha1:1XIBavHXckLba3r5/lWhEjdJpBY= sha1:2HsMNv0CY5WUeIKNMhJCab3Wb5g= Xref: csiph.com comp.lang.php:16053 Jerry Stuckle writes: > On 1/1/2016 12:24 PM, Arno Welzel wrote: >> Jerry Stuckle schrieb am 2016-01-01 um 15:32: >> >>> On 12/31/2015 9:22 PM, Lew Pitcher wrote: >>>> On Thursday December 31 2015 20:57, in >>>> comp.lang.php, "vjp2.at@at.BioStrategist.dot.dot.com" >>>> wrote: >>>> >>>>> >>>>> Should this work? >>>> >>>>> I'm stuck with lynx browser for a few days and can't tell >>>> >>>> That shouldn't stop you, assuming that you have a PHP-enabled webserver to >>>> host the page on. >>>> >>>> Lynx, like all browsers, just renders the html sent to it by the server. >>>> >>>> PHP code executes on the server. >>>> >>>> If the html with PHP is served from a PHP-enabled web server, lynx will render >>>> the results correctly. >>>> >>>>> >>>>> >>>>> Quadratic >>>>> >>>>> >>>>> >>>> $t; >>>> >>>> What is $t ? >>>> Why are you trying to execute it as a php statement? >>>> >>>>> $b=$_POST['b'];$a=$_POST['a'];$c=$_POST['c']; >>>> >>>> Here, you should test whether the page is invoked from a GET or a POST. None >>>> of the $_POST variables will be set on the initial GET, and your later >>>> computation will be invalid. >>>> >>> >>> In addition, you should check to see if the values are actually set. >>> Even if it came here from a POST request, there is no guarantee the >>> values have been set. >>> >>> $b = isset($_POST['b']) ? $_POST['b'] : ''; >>> >>> puts an empty string in $b $_POST['b'] is not set. You could also use 0 >>> instead of '' or any other default value you wish. >>> >>>>> $x;$y; >>>> >>>> Same question as above with $t. What is $x? What is $y? Why are you trying to >>>> execute two variables as php statements? >>>> >>>>> $t=(pow($b,2))-(4*$a*$c); >>>> >>>> Meaningless (and possibly errant) results on GET >>>> >>> >>> The advantage to using '' as a default value above is you can test here: >>> >>> if ($a == '' || $b == '' || $c = '') { >> >> Of course this should be the opposite as one would do the calculation >> only if *all* values are set and not if any of the value is empty: >> >> if ($a != '' && $b != '' && $c != '') { >> >> It would also be nice to see the values entered as default in the input >> elements and to have valid HTML. And finally it is not neccessary to use >> >> echo sprintf(...) >> >> as there is printf() as well which outputs the result directly. >> >> So the whole script could be like this: >> >> >> >> >> >> Quadratic >> >> >> > $a = isset($_POST['a']) ? $_POST['a'] : ''; >> $b = isset($_POST['b']) ? $_POST['b'] : ''; >> $c = isset($_POST['c']) ? $_POST['c'] : ''; >> >> if ($a != '' && $b != '' && $c != '') { >> $t=(pow($b,2))-(4*$a*$c); >> if($t<=0) >> $t=(-1)*$t; >> $x=(-2*$c)/($b+(sqrt($t))); >> $y=(-2*$c)/($b-(sqrt($t))); >> printf( >> "

Solution in Addition = %f in Subtraction = %f

", >> $x, $y); >> } >> ?> >> >> >> >> >> >> But next time you promise to do your homework on your own, yes? ;-) >> >> > > Sorry, I meant the code to go in the else clause, with an empty then clause. Also - unless you're using an outdated version of PHP for some reason, you no longer have to write code like: $x = isset($_GET['x']) ? $_GET['x'] : ''; You can use the null coalesce operator: $x = $_GET['x'] ?? ''; -- Matthew Carter (m@ahungry.com) http://ahungry.com