Check if Variable is empty. if so, set value. else, perform function

Question

Can this be done?

I created a form which performs the function giveReaction. Can anybody tell me what I'm doing wrong?

This is my code so far:

function giveReaction (){
    global $firstname;
    if ( empty($firstname) ) {
        $firstname = 'fill in your name, and get a response.';
        echo "$firstname";
    }
    else {
        $firstname = $_GET['firstname'];
        echo "hello, $firstname";
    }
}

echo "<form action=\"index.php?func_name=giveReaction()\" method=\"GET\">
        <input type=\"text\" name=\"firstname\">
        <input type=\"submit\" value=\"send\">
      </form>";

giveReaction();

I bet you're falling in the else all the time, right? Say what's the problem if not. — Navid
– Navid, Commented Apr 1, 2016 at 0:47
You never set $firstname. Take a look at some php forms tutorial — fusion3k
– fusion3k, Commented Apr 1, 2016 at 0:49

Rob Milward · Accepted Answer · 2016-04-01 01:08:17Z

There are a two immediate problems with your code:

You never define $firstname prior to checking it's empty
The action in your form does nothing, as you never handle func_name - this is not a built in feature of the language

To start fixing your code, you need to correctly handle the firstname input when the form has been submitted, for example:

$firstname = isset($_GET['firstname']) ? $_GET['firstname'] : '';

This ensures that $firstname will be the submitted value, or an empty string if it hasn't been provided yet.

So then you can define your function as follows:

function giveReaction (){
    $firstname = isset($_GET['firstname']) ? $_GET['firstname'] : '';
    if ( empty($firstname) ) {
        echo 'fill in your name, and get a response.';
    } else {
        echo "hello, $firstname";
    }
}

Secondly adjust your form to remove the unnecessary action, as by default forms will submit to the current page, and the func_name parameter isn't used.

echo "<form method=\"GET\">
    <input type=\"text\" name=\"firstname\">
    <input type=\"submit\" value=\"send\">
  </form>";

Then you can finish as you have, by calling your function.

giveReaction();

AbsoluteBeginner · Accepted Answer · 2020-08-30 14:57:11Z

0

Your function can simply be:

function giveReaction() {
  $firstname = $_GET['firstname'];
  echo $firstname ? "hello, $firstname" : 'fill in your name, and get a response.';
}

There's no need to add it to the form.

edited Aug 30, 2020 at 14:57

answered Aug 30, 2020 at 14:41

AbsoluteBeginner

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