How do i clear this array by user input in php/html?

Question

I am working on a program that has the user type in their course, first name, last name, and description of a program. The code is mostly done except for getting the clear the array button to work. When I use the unset array to clear the array on its own, it works but then the user cant enter in more data. I want to have the user be able to clear the data. Here is my code:

<?php
session_start();
?>
<html lang="en" xmlns="http://www.w3.org/1999/xhtml">

<head>

<script>
function showHint(str) {
if (str.length == 0) {
    document.getElementById("txtHint").innerHTML = "";
    return;
} else {
    var xmlhttp = new XMLHttpRequest();
    xmlhttp.onreadystatechange = function() {
        if (this.readyState == 4 && this.status == 200) {
            document.getElementById("txtHint").innerHTML = this.responseText;
        }
    }
    xmlhttp.open("GET", "gethint.php?q="+str, true);
    xmlhttp.send();
}
}
</script>
<?php
function clear(){   //this is the problem
    unset($_SESSION['courses']);
    return true;
}
?>

 </head>
<body>
<form method="POST">
  Course: <input type="text" name="courses" />
   <br /><br />
   First Name: <input type="text" name="firstname" />
   <br /><br />
    Last Name: <input type="text" name="lastname" />
    <br /><br />
    Description: <input type="text" name="description" />
    <br /><br />
    <input type="submit" name="submit" value="Submit">
</form>

<?php 
// First we check if the form has been sent and we have a value
if (!empty($_POST['courses'])) {
 if (!isset($_SESSION['courses']))
    $_SESSION['courses'] = array(); // Initialize the array if it doesn't exist

// Add the value to our array
$_SESSION['courses'][] = array("course" => $_POST['courses'],
                                "firstname" => $_POST['firstname'],
                                 "lastname" => $_POST['lastname'],
                                "description" => $_POST['description']); 
}

// If there are values to show, print them!
if (!empty($_SESSION['courses'])) {
foreach ($_SESSION['courses'] as $course) {
    echo $course['course']."    ".
          $course['firstname']."    ".
          $course['lastname']."    ".
         $course['description']."    ".
        "<br />";
}
}


?>
 <input type="submit" name="Clear" value="Clear"  onclick="clear()"> //this is the problem
<?php

?>

</body>
</html>

Can someone please help?

theres not an error exactly, the button just wont clear the array, its a pressing the button and nothing happening issue — Raheem Harris
– Raheem Harris, Commented Nov 18, 2016 at 0:51

user6061856 · Accepted Answer · 2016-11-18 01:01:07Z

1

<?php

// there is nothing wrong with this function.

function clear() {
    unset($_SESSION['courses']);
    return true;
}

?>

Okay, this function is fine, there is nothing wrong with it. But, you can't use this function like:

<input type="submit" name="Clear" onclick="Clear()" /> <!-- this is the problem -->

You see that onclick="Clear()", and that php function clear()? Yeah, you can't execute php functions with a html onclick="". You can only do that with javascript functions.

But you can do something like this:

<?php

if(isset($_POST['Clear']))
{
  // if the user submits the form, then the following code will be executed.
  clear();
}

?>

answered Nov 18, 2016 at 1:01

user6061856

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2 Comments

Raheem Harris Over a year ago

ah so i get rid of the onclick and then instead add the if statement?

user6061856 Over a year ago

Yep, that's all you have to do!

geeves · Accepted Answer · 2016-11-18 00:56:06Z

1

<input type="submit" name="Clear" value="Clear"  onclick="clear()">

clear() would be calling a javascript function. You have correctly written a php function.

Check the value of the submit button "Clear" to be "clear" and if true run the PHP function clear().

if ($_POST['Clear'] === 'clear') {
    clear();
}

answered Nov 18, 2016 at 0:56

geeves

6618 silver badges24 bronze badges

1 Comment

Raheem Harris Over a year ago

hmm im not sure i understand correctly, i added the if statement and but it still doesnt clear the array on clicking the button

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