get multiple checkbox value in php

1To pass the multiple checkbox values in one POST action in PHP you can refer below code:
2
3Html form code
4<form method="post" action="send_data.php">
5    <input type="checkbox" name="username[]" value="user1">User1
6    <input type="checkbox" name="username[]" value="user2">User2
7    <input type="checkbox" name="username[]" value="user3">User3
8    <input type="checkbox" name="username[]" value="user4">User4
9    <input type="submit" name="submit_data"/>
10</form>
11send_data.php
12<?php
13if(isset($_POST["submit_data"])){
14   if(!empty($_POST["username"])){
15       // to check the username checkboxes values you can use loop to display each checkbox value
16       $usernames = $_POST["username"];
17       foreach($usernames as $user){
18            echo "User Name :".$user;
19       }
20   } 
21}
22?>