Re: test prog inpu tpost

From	Matthew Carter <m@ahungry.com>
Newsgroups	comp.lang.php
Subject	Re: test prog inpu tpost
Date	2016-01-01 21:40 -0500
Organization	Ahungry (http://ahungry.com)
Message-ID	<87fuygd7qu.fsf@ahungry.com> (permalink)
References	<n64mdp$ppg$1@reader1.panix.com> <kplhy.63798$MN2.2950@fx07.iad> <n662gh$hm$1@jstuckle.eternal-september.org> <5686B656.3040603@arnowelzel.de> <n66ikt$thi$1@jstuckle.eternal-september.org>

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Jerry Stuckle <jstucklex@attglobal.net> 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"
>>>> <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? ;-)
>> 
>> 
>
> 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

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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