PHP Index error undefined

Question

I would like to capture values from the input , calculate and display the result on the same page, but for some reason I keep getting this error:

Notice: Undefined index: inputval in C:\xampp\htdocs\php\exercise 2\exercise2-3.php on line 67

here is what I have done so far.A user enters 2+ 3 or 5 * 4 or 5-4 etc.

<div class="div">
    <h1>My Calculator</h1>
    <form method="POST">
    <?php

    echo "      <input type='text' name='inputval' size='15' class='inputs' /><input class='button' type='submit' name='register' value='Register'>
    </form>
    <p>";

        $string =$_POST["inputval"];
        $value = eval($string);

        echo "Result is:".$value;

        ?>
    </p>
</div>

No infact, I want the result to be displayed on the same page — Navy, Mar 03 '14 at 00:01
running `eval` on an arbitrary variable posted from your form is **very** unsecure — scrowler, Mar 03 '14 at 00:01
Read the question+answer linked by @Phil and take what @scrowler mentioned extremely seriously (Google information about security issues with `eval`). — Marty, Mar 03 '14 at 00:05

Akshay Kalose · Answer 1 · 2014-03-03T00:19:46.767

1

<div class="div">
<h1>My Calculator</h1>
<form action="" method="POST">

<input type="text" name="inputval" size="15" class="inputs">
<input class="button" type="submit" name="register" value="Register">
</form>
<p>
    <?php
    if (!empty($_POST['inputval'])) {
        $string = $_POST['inputval'];
        $value = eval($string);

        echo 'Result is: ' . $value;
    }
    ?>
</p>

Start the php tag later on after your input tag's instead of echo'ing them in your php script. And check for input, else the code will still run even when there is no POST.

empty() will check if the array == false (if no values) or it is not set !isset().

!empty() will run when the value inside is not false or if values are set in the array.

edited Mar 03 '14 at 00:19

answered Mar 03 '14 at 00:05

Akshay Kalose

787
1
5
15

`isset($_POST["inputval"])` would make more sense. – Marty Mar 03 '14 at 00:07
@Marty Indeed. In fact, `isset($_POST)` will **always** return `true` – Phil Mar 03 '14 at 00:07
@Phil I was trying to be subtle ;) – Marty Mar 03 '14 at 00:08
Oh yes, sorry. I have updated the code, this should work. – Akshay Kalose Mar 03 '14 at 00:08
I still get the error Undefined index: inputval – Navy Mar 03 '14 at 00:13
right when the php tag starts put `var_dump($_POST);`. Submit a value in the form, submit, and then tell me the output. – Akshay Kalose Mar 03 '14 at 00:17
This is what I got: array(2) { ["inputval"]=> string(5) "10+20" ["register"]=> string(8) "Register" } Parse error: syntax error, unexpected end of file in C:\xampp\htdocs\php\exercise 2\exercise2-3.php(68) : eval()'d code on line 1 Result is: – Navy Mar 03 '14 at 00:20
What is at the end of your file? – Akshay Kalose Mar 03 '14 at 00:22
You mean the file extension ? – Navy Mar 03 '14 at 00:24
At the bottom of the file in text editor – Akshay Kalose Mar 03 '14 at 00:25
My Calculator

– Navy Mar 03 '14 at 00:30
That's all I have nothing more – Navy Mar 03 '14 at 00:30
Hmm search around for 'Parse error: syntax error, unexpected end of file' – Akshay Kalose Mar 03 '14 at 00:32
that's what I currently have: Parse error: syntax error, unexpected end of file in C:\xampp\htdocs\php\exercise 2\exercise2-3.php(67) : eval()'d code on line 1 Result is: – Navy Mar 03 '14 at 00:34

PHP Index error undefined

1 Answers1

My Calculator