Re: test prog inpu tpost

From	Arno Welzel <usenet@arnowelzel.de>
Newsgroups	comp.lang.php
Subject	Re: test prog inpu tpost
Date	2016-01-01 18:24 +0100
Message-ID	<5686B656.3040603@arnowelzel.de> (permalink)
References	<n64mdp$ppg$1@reader1.panix.com> <kplhy.63798$MN2.2950@fx07.iad> <n662gh$hm$1@jstuckle.eternal-september.org>

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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"
>> <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.
>>  
>>> <html>
>>> <head>
>>> <title>Quadratic</title>
>>> </head>
>>> <body>
>>> <?php
>>>   $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:


<!DOCTYPE html>
<html>
<head>
<title>Quadratic</title>
</head>
<body>
<?php
$a = isset($_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(
      "<p>Solution in Addition = %f in Subtraction = %f</p>",
      $x, $y);
}
?>
<form method="post">
<label>What is a?
<input type="number" name="a"
value="<?php echo htmlspecialchars($a); ?>"></label><br />

<label>What is b?
<input type="number" name="b"
value="<?php echo htmlspecialchars($b); ?>"></label><br />

<label>What is c?
<input type="number" name="c"
value="<?php echo htmlspecialchars($c); ?>"></label><br />

<input type="submit">
</form>
</body>
</html>


But next time you promise to do your homework on your own, yes? ;-)


-- 
Arno Welzel
http://arnowelzel.de
http://de-rec-fahrrad.de
http://fahrradzukunft.de

Thread

test prog inpu tpost vjp2.at@at.BioStrategist.dot.dot.com - 2016-01-01 01:57 +0000
  Re: test prog inpu tpost Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-12-31 21:22 -0500
    Re: test prog inpu tpost Matthew Carter <m@ahungry.com> - 2015-12-31 21:40 -0500
    Re: test prog inpu tpost "J.O. Aho" <user@example.net> - 2016-01-01 09:40 +0100
    Re: test prog inpu tpost Jerry Stuckle <jstucklex@attglobal.net> - 2016-01-01 09:32 -0500
      Re: test prog inpu tpost Arno Welzel <usenet@arnowelzel.de> - 2016-01-01 18:24 +0100
        Re: test prog inpu tpost Jerry Stuckle <jstucklex@attglobal.net> - 2016-01-01 14:07 -0500
          Re: test prog inpu tpost Matthew Carter <m@ahungry.com> - 2016-01-01 21:40 -0500
            Re: test prog inpu tpost Jerry Stuckle <jstucklex@attglobal.net> - 2016-01-01 21:53 -0500
            Re: test prog inpu tpost Arno Welzel <usenet@arnowelzel.de> - 2016-01-02 11:39 +0100
            Re: test prog inpu tpost Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-02 22:43 +0100
  Re: test prog inpu tpost Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-12-31 21:39 -0500
  Re: test prog inpu tpost vjp2.at@at.BioStrategist.dot.dot.com - 2016-01-07 03:19 +0000

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