<div>
You are referencing values that do not exist when that page loads. &nbsp;PHP is server side, not client side. &nbsp;Only page.php, the target of your form will contain a value for the courses array. &nbsp;Even then, you should wrap the code that references the courses array in an isset check, like so: 
 

<pre><code class="code-10 nolinks" id="code-20-42062984-1">&lt;?php

if (isset($_POST['courses'])
{
 foreach($_POST['courses'] as $values)
 {
 echo $values;
 }
}
?&gt;
</code></pre>
 
By doing that, you will prevent PHP from throwing an error in case the variable has not been set.
</div>

<div>
use isset fuction to check if the POST has values, Pleas check the below code 
 

<pre><code class="code-10 nolinks" id="code-20-42062990-1">&lt;?php

if (isset($_POST['courses'])) 
{ 
	foreach($_POST['courses'] as $values)
	{
		echo $values;
	}
}
?&gt;
</code></pre>
</div>

<div>
It shows me nothing, try it 
 
 

<pre><code class="code-10 nolinks" id="code-20-42063009-1">&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;head&gt;
 &lt;title&gt;&lt;/title&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;form action=&quot;#&quot; method=&quot;post&quot;&gt;&lt;input type=&quot;checkbox&quot; name=&quot;courses[]&quot; value=&quot;photoshop&quot;/&gt;
&lt;input type=&quot;checkbox&quot; name=&quot;courses[]&quot; value=&quot;php&quot;/&gt;

&lt;input type=&quot;checkbox&quot; name=&quot;courses[]&quot; value=&quot;html&quot;/&gt;

&lt;input type=&quot;checkbox&quot; name=&quot;courses[]&quot; value=&quot;javascript&quot;/&gt;

&lt;/form&gt;

&lt;?php

if (isset($_POST['courses'])) 
{ 
	foreach($_POST['courses'] as $values)
	{
		echo $values;
	}
}
?&gt;

&lt;/body&gt;
&lt;/html&gt;
</code></pre>
</div>

<div>
Of course it shows you nothing! &nbsp;It's working exactly the right way. &nbsp;I think we have a fundamental misunderstanding of the timeline of HTTP request and response. &nbsp;It's too much to write in an answer to this and your other question, but we have an article here that explains it. 
<a href="https://www.experts-exchange.com/articles/11271/Understanding-Client-Server-Protocols-and-Web-Applications.html" rel="ugc">https://www.experts-exchange.com/articles/11271/Understanding-Client-Server-Protocols-and-Web-Applications.html</a> 
 
If you're new to PHP and want to learn the language and associated technologies, this article can help you find well-vetted learning resources, and perhaps more importantly, it can help you avoid all of the bad, incompetent, outdated and insecure examples that litter the internet! 
<a href="https://www.experts-exchange.com/articles/11769/And-by-the-way-I-am-New-to-PHP.html" rel="ugc">https://www.experts-exchange.com/articles/11769/And-by-the-way-I-am-New-to-PHP.html</a>
</div>

<div>
Refer to my original answer. &nbsp;The PHP code that is trying to access the courses array is in checkbox.php, however your form is set to send the data to page.php. &nbsp;If you want to see the data, change the form target to checkbox.php, and when you submit it you will see the data.
</div>

<div>
Try it like this. &nbsp;There is a &quot;submit&quot; button in the form, because that is how we get the information from the client browser to the server. &nbsp;I removed the &quot;page.php&quot; from the form tag, so that the script will submit the request to itself. 
 
You can test this on my server, here: <a href="https://iconoun.com/demo/temp_hachem.php" rel="ugc">https://iconoun.com/demo/temp_hachem.php</a> 
&nbsp;
<pre><code class="code-10 nolinks" id="code-20-42063042-1">&lt;?php // demo/temp_hachem.php
/**
 * https://www.experts-exchange.com/questions/29011455/Php-Get-value-checkbox-when-checked-In-php.html
 * https://www.experts-exchange.com/questions/29011219/Equivalence-of-serialize-in-PHP.html
 */

// IF THERE IS A POST-METHOD REQUEST
if (!empty($_POST))
{
 foreach($_POST['courses'] as $values)
 {
 echo PHP_EOL . $values;
 }
}
?&gt;
&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;head&gt;
 &lt;title&gt;&lt;/title&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;form method=&quot;post&quot;&gt;
&lt;input type=&quot;checkbox&quot; name=&quot;courses[]&quot; value=&quot;photoshop&quot;/&gt;
&lt;input type=&quot;checkbox&quot; name=&quot;courses[]&quot; value=&quot;php&quot;/&gt;
&lt;input type=&quot;checkbox&quot; name=&quot;courses[]&quot; value=&quot;html&quot;/&gt;
&lt;input type=&quot;checkbox&quot; name=&quot;courses[]&quot; value=&quot;javascript&quot;/&gt;

&lt;input type=&quot;submit&quot; /&gt;

&lt;/form&gt;

&lt;/body&gt;
&lt;/html&gt;
</code></pre>
</div>

<div>
<h2>Is there a way to get the value of a checkbox without the submit button</h2>
</div>

<div>
<blockquote>
Is there a way to get the value of a checkbox without the submit button
</blockquote>
Not in PHP, at least not in any practical sense, no. &nbsp;Your client (probably a browser) must make an HTTP request to the server before PHP can even start running. 
 
Please read the articles I linked before. &nbsp;You need some more foundation information to understand this issue, and it will be easier to discuss when you have that information. 
 
Now having said that, here is a sequence that is programmable, but terribly impractical and culturally inappropriate. &nbsp;You can trigger an AJAX request to the server when the checkbox is clicked. &nbsp;For that matter you could even trigger an AJAX request on a mouseover event. 
 
What's wrong with this idea? 
 
1. Human beings know that checkboxes on the WWW don't work this way. &nbsp;Checkboxes can be checked and unchecked before submitting them. 
 
2. You will need to have a PHP listener script on your server to listen for the AJAX request. 
 
3. The listener script will have to be stateful, recording (at least) the IP address and user-agent that clicked the checkbox. 
 
4. If the client unchecks the checkbox, the stateful information will have to be erased. 
 
5. If the client visits the site, checks a checkbox, then closes the browser, what are you going to do with the stateful information? 
 
6. How will you communicate with the client again? &nbsp;How will you know that they once came to the site and clicked a checkbox? 
 
7. A web site that makes an AJAX request on a checkbox click feels like &quot;spooky action at a distance,&quot; and it will probably make people feel like you are trying to trick them into something. &nbsp;They will go away and never come back, or report your site to Google as a potential attack site. 
 
It's points of confusion like these that make me say you really want a submit button. &nbsp;It's always easier to ride the horse in the direction he is going! :-)
</div>

<div>
i want that when i check a checkbox , the value of checkbox stock in a value , &nbsp;So I can change the URL. 
 
 
&lt;?php 
 
 
$query = Input::get('query', ''); 
for($i=1; $i&lt;=$nbPages; $i++) //On fait notre boucle 
{ 
&nbsp; &nbsp; &nbsp;//On va faire notre condition 
&nbsp; &nbsp; &nbsp;if($i==$pageActuelle) //Si il s'agit de la page actuelle... 
&nbsp; &nbsp; &nbsp;{ 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;echo '&lt;span&gt;&lt;a&gt; &nbsp;'.$i.' &nbsp;&lt;/a&gt;&lt;/span&gt;'; 
&nbsp; &nbsp; &nbsp;} &nbsp; 
&nbsp; &nbsp; &nbsp;else //Sinon... 
&nbsp; &nbsp; &nbsp;{ 
&nbsp; &nbsp; echo '&lt;span&gt;&lt;a href=&quot;/pricefilter?query=' . $query.'&amp;priceFilter[]='.$sq.'&amp;page='.$i.'&quot;&gt;'.$i.'&lt;/a&gt;&lt;/span&gt;'; 
&nbsp; &nbsp; &nbsp;} 
} 
 
?&gt;
</div>

<div>
still not clear on what you want to do. 
 
You have a page with checkboxes. 
 
A checkbox is clicked - what happens next?
</div>

<div>
Input::get() seems like an out-of-date version of Laravel. &nbsp;The current way is described here: 
<a href="https://laracasts.com/discuss/channels/laravel/how-to-use-use-inputget-globally-in-larvel-52" rel="ugc">https://laracasts.com/discuss/channels/laravel/how-to-use-use-inputget-globally-in-larvel-52</a> 
 
Are you using Laravel or another framework for your application?
</div>

<div>
Although the author never clarified what his actual intent was, I believe that Ray found the meat of the issue and displayed the best solution, although Julian's comment was also helpful.
</div>

<div>
<div class="content wysiwyg-content">
<pre><code class="code-10 nolinks" id="code-10-29011455-1">&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;head&gt;
	&lt;title&gt;&lt;/title&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;form action=&quot;page.php&quot; method=&quot;post&quot;&gt;&lt;input type=&quot;checkbox&quot; name=&quot;courses[]&quot; value=&quot;photoshop&quot;/&gt;
&lt;input type=&quot;checkbox&quot; name=&quot;courses[]&quot; value=&quot;php&quot;/&gt;

&lt;input type=&quot;checkbox&quot; name=&quot;courses[]&quot; value=&quot;html&quot;/&gt;

&lt;input type=&quot;checkbox&quot; name=&quot;courses[]&quot; value=&quot;javascript&quot;/&gt;

&lt;/form&gt;

&lt;?php

foreach($_POST['courses'] as $values)
{
echo $values;
}
?&gt;

&lt;/body&gt;
&lt;/html&gt;
</code></pre>
 
 
 
Notice: Undefined index: courses in C:\xampp\htdocs\testCheckbox\checkbox.php on line 18 
 
Warning: Invalid argument supplied for foreach() in C:\xampp\htdocs\testCheckbox\checkbox.php on line 18
</div>
</div>

(CODE)



Notice: Undefined index: courses in C:\xampp\htdocs\testCheckbox\checkbox.php on line 18

Warning: Invalid argument supplied for foreach() in C:\xampp\htdocs\testCheckbox\checkbox.php on line 18

Php - Get value checkbox when checked In php

HTML (HyperText Markup Language) is the main markup language for creating web pages and other information to be displayed in a web browser, providing both the structure and content for what is sent from a web server through the use of tags. The current implementation of the HTML specification is HTML5.

HTML

PHP is a widely-used server-side scripting language especially suited for web development, powering tens of millions of sites from Facebook to personal WordPress blogs. PHP is often paired with the MySQL relational database, but includes support for most other mainstream databases. By utilizing different Server APIs, PHP can work on many different web servers as a server-side scripting language.

JavaScript is a dynamic, object-based language commonly used for client-side scripting in web browsers. Recently, server side JavaScript frameworks have also emerged. JavaScript runs on nearly every operating system and  in almost every mainstream web browser.

JavaScript

The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, hypermedia information systems. Hypertext is structured text that uses logical links (hyperlinks) between nodes containing text. HTTP is the protocol to exchange or transfer hypertext. HTTP functions as a request-response protocol in the client-server computing model. HTTP is designed to permit intermediate network elements to improve or enable communications between clients and servers. HTTP is an application layer protocol designed within the framework of the Internet Protocol Suite; it presumes an underlying and reliable transport layer protocol.