<form action="" method="post">
<input type="checkbox" name="check_list[]" alt="Checkbox" value="one">
<input type="checkbox" name="check_list[]" alt="Checkbox" value="two">
<input type="checkbox" name="check_list[]" alt="Checkbox" value="three">
<button type="submit">submit</button>
</form>

<?php

echo "Check box test<pre>" ;
print_r($check_list); 
echo "</pre>";
if(!empty($_POST['check_list'])) {
foreach($_POST['check_list'] as $check) {
echo "check=$check<br>"; 
}
}
?>

Check box test

Array
(
 [0] => one
 [1] => two
 [2] => three
)

check=one
check=two
check=three

//create array to temporarily grab variables
$input_arr = array();
//grabs the $_POST variables and adds slashes
foreach ($_POST as $key => $input_arr) {
  $_POST[$key] = addslashes($input_arr);
}

addslashes — Quote string with slashes

foreach ($_POST as $key => $value) { 
 if (is_array($value)) { 
 // reset the temporary array 
 $input_arr = array(); 
 foreach ($value as $array_val) { 
 // Build the temporary array of values 
 array_push($input_arr,addslashes($array_val)); 
 } 
 // After array is stepped through, NOW replace this key with the array 
 $_POST[$key] = $input_arr; 
 } 
 else { $_POST[$key] = addslashes($value); } 
} 

Huh? addslashes() [php.net] is internal to PHP.