Joan: /* Gestió dels errors */

2017-11-23T16:41:52Z

Gestió dels errors

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__TOC__
=Exemples vistos a classe=
'''Taules de multiplicar amb dos bucles for anidats''':
<pre>
<!DOCTYPE html>
<html>
<head>
<title>Taules de multiplicar</title>
</head>
<body>
<h1>Taules de multiplicar</h1>
<?php

for ($y=1; $y<=10; $y++) {
echo "<table border=\"1\">";
for ($x=1; $x<=10; $x++) {
echo "<tr><td>".$y." * ".$x." = </td><td>".$x*$y."</td></tr>";
}
echo "</table>";
echo "<br />";
}
?>

</body>
</html>
</pre>
'''Celsius to Fahrenheit'''

hem fet una cerca ràpida a Google per trobar la funció que necessitem:
*http://learnsphponline.blogspot.com.es/2013/11/create-temperature-converter-in-php.html
Sense necessitat d'entendre la funció, la gràcia de la programació estructurada és que no cal que entengui la funció. Només he de saber com fer-la servir en el meu codi.

<pre>
<?php
function fahrenheit_to_celsius($given_value)
{
$celsius=5/9*($given_value-32);
return $celsius ;
}

function celsius_to_fahrenheit($given_value)
{
$fahrenheit=$given_value*9/5+32;
return $fahrenheit ;
}

?>

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Celsius to Fahrenheit</title>
</head>
<body>
<h1>Celsius to Fahrenheit</h1>
<?php

echo "35ºC són ".celsius_to_fahrenheit(35)." F";
?>

</body>
</html>
</pre>
'''Formulari amb persistència de les dades i gravar les dades a un fitxer''':
<pre>
<html>
<head>
<meta charset="UTF-8">
</head>
<body>
<h1>Demanar informació</h1>
<?php include 'llibreria.php';?>

<?php
// define variables and set to empty values
$name = $email = $gender = $comment = $website = "";

if ($_SERVER["REQUEST_METHOD"] == "POST") {

$name = test_input($_POST["name"]);
$email = test_input($_POST["email"]);
$website = test_input($_POST["website"]);
$comment = test_input($_POST["comment"]);
$gender = test_input($_POST["gender"]);

if (empty($_POST["name"]) || empty($_POST["email"])) {
$nameErr = "Name and email are required";
echo $nameErr;
} else {

$myfile = fopen("client.txt", "a") or die("Unable to open file!");
fwrite($myfile, $name."\n");
fwrite($myfile, $email."\n");
fwrite($myfile, $website."\n");
fwrite($myfile, $comment."\n");
fwrite($myfile, $gender."\n");
fwrite($myfile, "===================\n");
fclose($myfile);

echo $name."<br />";
echo $email."<br />";
echo $website."<br />";
echo $comment."<br />";
echo $gender."<br />";
}
}

?>

<form action="form4.php" method="post">
Name: <input type="text" name="name" value="<?php echo $name ?>"> *<br />
E-mail: <input type="text" name="email" value="<?php echo $email ?>"> *<br />
Website: <input type="text" name="website" value="<?php echo $website ?>"><br />
Comment: <textarea name="comment" rows="5" cols="40"><?php echo $comment ?></textarea><br />
<input type="radio" name="gender" value="female">Female
<input type="radio" name="gender" value="male">Male<br />
<input type="submit">
</form>

</body>
</html>
</pre>
==Exercicis proposats==
1. Posem en un array associatiu (http://www.w3schools.com/php/php_arrays.asp) els mesos i el número de dies que té cada mes. Utilitzant un bucle que recorri l'array, posar tots els dies de l'any 2016:
<pre>
1 gen
2 gen
...
31 gen
1 feb
...
29 feb
...
31 des
</pre>
'''Solució''':
<pre>
<html>
<head>
<title>Exercici proposat 1</title>
<meta charset="UTF-8">
</head>
<body>
<h1>Exercici proposat 1</h1>
<h2>Dies de l'any</h2>
<?php
//http://www.w3schools.com/php/php_arrays.asp
$mesos = array("Gener"=>"31", "Febrer"=>"29", "Març"=>"31", "Abril"=>"30", "Maig"=>"31", "Juny"=>"30", "Juliol"=>"31", "Agost"=>"31", "Setembre"=>"30", "Octubre"=>"31", "Novembre"=>"30", "Desembre"=>"31");

foreach($mesos as $mes => $num_dia) {
//echo "mes=" . $mes . ", num_dies=" . $num_dia . "<br />";
for ($i=1; $i<=$num_dia;$i++) {
echo $i." ".$mes;
echo "<br />";
}
echo "<br />";
}

?>
</body>
</html>
</pre>
2. Sabent que el 1 de gener del 2016 és divendres, formatar la següent sortida:
<pre>
divendres 1 gen
dissabte 2 gen
...
diumenge 31 gen
dilluns 1 feb
...
dilluns 29 feb
...
dissabte 31 des
</pre>
'''Solució''':
<pre>
<html>
<head>
<title>Exercici proposat 2</title>
<meta charset="UTF-8">
</head>
<body>
<h1>Exercici proposat 2</h1>
<h2>Dies de l'any i dies de la setmana</h2>
<?php
//http://www.w3schools.com/php/php_arrays.asp
$mesos = array("Gener"=>"31", "Febrer"=>"29", "Març"=>"31", "Abril"=>"30", "Maig"=>"31", "Juny"=>"30", "Juliol"=>"31", "Agost"=>"31", "Setembre"=>"30", "Octubre"=>"31", "Novembre"=>"30", "Desembre"=>"31");
$dies_setmana = array("dilluns", "dimarts", "dimecres", "dijous", "divendres", "dissabte", "diumenge");

$dia_setmana = 4;
foreach($mesos as $mes => $num_dia) {
//echo "mes=" . $mes . ", num_dies=" . $num_dia . "<br />";
for ($i=1; $i<=$num_dia;$i++) {
echo $dies_setmana[$dia_setmana]." ".$i." ".$mes;
$dia_setmana++;
if ($dia_setmana == 7) $dia_setmana=0;
echo "<br />";
}
echo "<br />";
}

?>
</body>
</html>
</pre>

3. Estem fent un concurs de relats curs. En el teu portal tens un petit formulari on demanes a la gent que fiqui el seu nom, comentari, i que envïi un document pdf de menys de 200K. Els documents aniran a parar dins la carpeta ''pdf/''. Referència:
*http://www.w3schools.com/php/php_file_upload.asp (Complete Upload File PHP Script)

=Gestió dels errors=
Per al programador és frustrant tenir un error en el script php i no tenir informació d'on s'ha produït l'error. Per ex, un simple error de sintaxi com deixar-se el punt i coma final produeix una pantalla blanca, i no tens ni idea d'on està l'error. La solució és fàcil, s'ha de configurar la ''gestió d'errors'' en el fitxer '''php.ini'''.

El fitxer '''php.ini''' normalment el trobaràs a:
*/etc/php5/apache2/php.ini
L'edites i mires la part de gestió d'errors:
<pre>
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Error handling and logging ;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

; This directive informs PHP of which errors, warnings and notices you would li
; it to take action for. The recommended way of setting values for this
; directive is through the use of the error level constants and bitwise
; operators. The error level constants are below here for convenience as well a
; some common settings and their meanings.
; By default, PHP is set to take action on all errors, notices and warnings EXC
; those related to E_NOTICE and E_STRICT, which together cover best practices a
; recommended coding standards in PHP. For performance reasons, this is the
; recommend error reporting setting. Your production server shouldn't be wastin
; resources complaining about best practices and coding standards. That's what
; development servers and development settings are for.
; Note: The php.ini-development file has this setting as E_ALL | E_STRICT. This
; means it pretty much reports everything which is exactly what you want during
; development and early testing.
;
; Error Level Constants:
; E_ALL - All errors and warnings (includes E_STRICT as of PHP 6.0.
; E_ERROR - fatal run-time errors
; E_RECOVERABLE_ERROR - almost fatal run-time errors
; E_WARNING - run-time warnings (non-fatal errors)
; E_PARSE - compile-time parse errors
; E_NOTICE - run-time notices (these are warnings which often result
; from a bug in your code, but it's possible that it was
; intentional (e.g., using an uninitialized variable and
; relying on the fact it's automatically initialized to an
; empty string)
; E_STRICT - run-time notices, enable to have PHP suggest changes
; to your code which will ensure the best interoperability
; and forward compatibility of your code
; E_CORE_ERROR - fatal errors that occur during PHP's initial startup
; E_CORE_WARNING - warnings (non-fatal errors) that occur during PHP's
; initial startup
; E_COMPILE_ERROR - fatal compile-time errors
; E_COMPILE_WARNING - compile-time warnings (non-fatal errors)
; E_USER_ERROR - user-generated error message
; E_USER_WARNING - user-generated warning message
; E_USER_NOTICE - user-generated notice message
; E_DEPRECATED - warn about code that will not work in future versions
; of PHP
; E_USER_DEPRECATED - user-generated deprecation warnings
;
; Common Values:
; E_ALL & ~E_NOTICE (Show all errors, except for notices and coding standard
; E_ALL & ~E_NOTICE | E_STRICT (Show all errors, except for notices)
; E_COMPILE_ERROR|E_RECOVERABLE_ERROR|E_ERROR|E_CORE_ERROR (Show only errors
; E_ALL | E_STRICT (Show all errors, warnings and notices including coding s
; Default Value: E_ALL & ~E_NOTICE
; Development Value: E_ALL | E_STRICT
; Production Value: E_ALL & ~E_DEPRECATED
; http://php.net/error-reporting
; error_reporting = E_ALL & ~E_DEPRECATED
; error_reporting = E_ALL & ~E_NOTICE
; error_reporting = E_WARNING & ~E_NOTICE & ~E_DEPRECATED
error_reporting = E_ALL & ~E_NOTICE
</pre>
Un valor correcte és
<pre>
error_reporting = E_ALL & ~E_NOTICE
</pre>
que vol dir que mostres tots els errors i warnings, i no mostris les notificacions.

També és important:
<pre>
display_errors = On
</pre>
{{Autor}}, novembre 2013, novembre 2017

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Joan: /* Gestió dels errors */