{"id":928,"date":"2021-04-06T15:03:28","date_gmt":"2021-04-06T15:03:28","guid":{"rendered":"https:\/\/phptutorial.net\/?page_id=928"},"modified":"2025-04-07T14:16:48","modified_gmt":"2025-04-07T14:16:48","slug":"php-checkbox","status":"publish","type":"page","link":"https:\/\/www.phptutorial.net\/php-tutorial\/php-checkbox\/","title":{"rendered":"PHP Checkbox"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you will learn how to use PHP to process a form with one or more checkboxes.<\/p>\n\n\n\n

A quick introduction to the checkbox element #<\/a><\/h2>\n\n\n\n

A checkbox allows you to select a single value for submission in a form. <\/p>\n\n\n\n

To create a checkbox, you use the input<\/code> element with the type checkbox<\/code> as follows:<\/p>\n\n\n

<input<\/span> type<\/span>=\"checkbox\"<\/span> name<\/span>=\"checkbox_name\"<\/span> value<\/span>=\"checkox_value\"<\/span>><\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
A checkbox has two states: checked and unchecked. <\/p>\n\n\n\n
If you check the checkbox and submit the form using the POST<\/code> method, the $_POST<\/code> associative array will contain an element whose key is checkbox_name<\/code> and value is checkbox_value<\/code>.<\/p>\n\n\n
echo<\/span> $_POST['checkbox_name'<\/span>]; \/\/ 'checkbox_value'<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
However, if you uncheck the checkbox and submit the form, the $_POST<\/code> won’t have any element with key checkbox_name<\/code>. It means that the following expression returns false<\/code>:<\/p>\n\n\n
isset<\/span>($_POST['checkbox_name'<\/span>])<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
if<\/span>(filter_has_var(INPUT_POST,'checkbox_name'<\/span>)) {\n     \/\/ ...<\/span>\n}<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
The filter_has_var()<\/code> function returns true<\/code> if the checkbox_name<\/code> exists in the INPUT_POST<\/code>.<\/p>\n\n\n\n
A checkbox has no label by default. Therefore, you should always use a checkbox with a <label><\/code> element like this:<\/p>\n\n\n
<input<\/span> type<\/span>=\"checkbox\"<\/span> name<\/span>=\"agree\"<\/span> id<\/span>=\"agree\"<\/span>><\/span>\n<label<\/span> for<\/span>=\"agree\"<\/span>><\/span>I agree<\/label<\/span>><\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, the value of the for<\/code> attribute of the <label><\/code> element is the same as the value of the id<\/code> attribute of the checkbox. When you associate a label with a checkbox, you can click the label to check or uncheck the checkbox.<\/p>\n\n\n\n
Another way to associate a checkbox with a label is to place the checkbox inside the label like this:<\/p>\n\n\n
<label<\/span>><\/span>\n    <input<\/span> type<\/span>=\"checkbox\"<\/span> name<\/span>=\"agree\"<\/span>><\/span> I agree\n<\/label<\/span>><\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
In this case, you don’t need to specify the id<\/code> for the checkbox and the for<\/code> attribute for the label.<\/p>\n\n\n\n
A simple PHP checkbox example #<\/a><\/h2>\n\n\n\n
We’ll create a form with one checkbox and a submit button<\/a>.<\/p>\n\n\n\n
First, create the following directory and file structure:<\/p>\n\n\n
.\n\u251c\u2500\u2500 css\n\u2502   \u2514\u2500\u2500 style.css\n\u251c\u2500\u2500 inc\n\u2502   \u251c\u2500\u2500 .htaccess\n\u2502   \u251c\u2500\u2500 get.php\n\u2502   \u2514\u2500\u2500 post.php\n\u2514\u2500\u2500 index.php<\/code><\/span>Code language:<\/span> plaintext<\/span> (<\/span>plaintext<\/span>)<\/span><\/small><\/pre>\n\n\n
File<\/th>Directory<\/th>Description<\/th><\/tr><\/thead>
index.php<\/td>.<\/td>Contain the main logic that loads get.php or post.php depending on the HTTP request method<\/td><\/tr>
header.php<\/td>inc<\/td>Contain the header code<\/td><\/tr>
footer.php<\/td>inc<\/td>Contain the footer code<\/td><\/tr>
get.php<\/td>inc<\/td>Contain the code for showing a form with a checkbox when the HTTP request is GET.<\/td><\/tr>
post.php<\/td>inc<\/td>Contain the code for handling POST request<\/td><\/tr>
.htaccess<\/td>inc<\/td>Prevent direct access to the files in the inc directory<\/td><\/tr>
style.css<\/td>css<\/td>Contain the CSS code<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
index.php #<\/a><\/h3>\n\n\n\n
Second, add the following code to the index.php<\/code> file:<\/p>\n\n\n
<?php<\/span>\n\nrequire<\/span> __DIR__<\/span> . '\/inc\/header.php'<\/span>;\n\n$errors = [];\n\n$request_method = $_SERVER['REQUEST_METHOD'<\/span>];\n\nif<\/span> ($request_method === 'GET'<\/span>) {\n\trequire<\/span> __DIR__<\/span> . '\/inc\/get.php'<\/span>;\n} elseif<\/span> ($request_method === 'POST'<\/span>) {\n\trequire<\/span> __DIR__<\/span> . '\/inc\/post.php'<\/span>;\n}\n\nif<\/span> ($errors) {\n\trequire<\/span> __DIR__<\/span> . '\/inc\/get.php'<\/span>;\n} \n\nrequire<\/span> __DIR__<\/span> . '\/inc\/footer.php'<\/span>;<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The index.php<\/code> loads the form from the get.php<\/code> file if the HTTP request method is GET. And it loads the post.php<\/code> file if the form is submitted.<\/p>\n\n\n\n
The $errors<\/code> variable is used to store error messages.<\/p>\n\n\n\n
header.php #<\/a><\/h3>\n\n\n\n
Third, place the following code to the header.php<\/code> file:<\/p>\n\n\n
<!DOCTYPE html<\/span>><\/span>\n<html<\/span> lang<\/span>=\"en\"<\/span>><\/span>\n\n<head<\/span>><\/span>\n    <meta<\/span> charset<\/span>=\"UTF-8\"<\/span> \/><\/span>\n    <meta<\/span> name<\/span>=\"viewport\"<\/span> content<\/span>=\"width=device-width, initial-scale=1.0\"<\/span> \/><\/span>\n    <title<\/span>><\/span>PHP Checkbox<\/title<\/span>><\/span>\n    <link<\/span> rel<\/span>=\"stylesheet\"<\/span> href<\/span>=\"css\/style.css\"<\/span>><\/span>\n<\/head<\/span>><\/span>\n\n<body<\/span> class<\/span>=\"center\"<\/span>><\/span>\n    <main<\/span>><\/span><\/code><\/span>Code language:<\/span> HTML, XML<\/span> (<\/span>xml<\/span>)<\/span><\/small><\/pre>\n\n\n
Try it<\/a><\/p>\n\n\n\n
To check if a checkbox is checked, you can also use the filter_has_var()<\/a><\/code> function like this:<\/p>\n\n\n