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Hi,

 

I've just started to learn php today from a book, and ive created this example for a calculator but i keep getting an error message saying there is an unidentified variable.

 

There is a html page with the forms on it:

 


<HTML>
<HRAD>
<TITLE>Caluclation Form</TITLE>
</HEAD>
<BODY>

<FORM METHOD="POST" ACTION="calculate.php">

<p>Value 1: <INPUT TYPE="text" NAME="val1" SIZE=10></p>

<p>Value 2: <INPUT TYPE="text" NAME="val2" SIZE=10></p>

<p>Calculation:<br>
<INPUT TYPE="radio" NAME="calc" VALUE="add"> add<br>
<INPUT TYPE="radio" NAME="calc" VALUE="subtract"> subtract<br>
<INPUT TYPE="radio" NAME="calc" VALUE="multiply"> multiply<br>
<INPUT TYPE="radio" NAME="calc" VALUE="divide"> divide</p>

<p><INPUT TYPE="submit" NAME="submit" VALUE="Calculate"></p>

</FORM>
</BODY>
</HTML>

 

and the php script in a nother file:

 


<php
if (($_POST[val1] == "") || ($_POST[val2] == "") || ($_POST[calc] == "")) {

header("Location: http://127.0.0.1/calculate_form.html");

}


if ($_POST[calc] == "add") {
$result = $_POST[val1] + $_POST[val2];
} else if ($_POST[calc] == "subtract") {
$result = $POST[val1]] - $_POST[val2];
} else if ($_POST[calc] == "multiply") {
$result = $POST[val1]] * $_POST[val2];
} else if ($_POST[calc] == "divide") {
$result = $POST[val1]] / $_POST[val2];
}


?>

<HTML>
<HEAD>
<TITLE>Calculation Result</TITLE>
</HEAD>
<BODY>

<p>The result of the calculation is: <?php echo "$result"; ?></p>

</BODY>
</HTML>

 

When you don't enter anything into the calc, it is meant to reload the page, but i get this:

 

The result of the calculation is:

Notice: Undefined variable: result in C:\wamp\www\calculate.php on line 28

 

 

 

Can anyone see what the problem is? Probably something really obvious but im stumped  :-\

 

Thanks!

 

 

 

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You also have other options that might be better to use, but it real depends on what you are trying to do.

You also don't need the extra brackets "()".

 

This

<?php
if ($_POST['val1'] == "" || $_POST['val2'] == "" || $_POST['calc'] == "") {
header("Location: http://127.0.0.1/calculate_form.html");
}
?>

 

Or This

<?php
if (empty($_POST['val1']) || empty($_POST['val2']) || empty($_POST['calc'])) {
header("Location: http://127.0.0.1/calculate_form.html");
}
?>

 

Or This

<?php
if (!isset($_POST['val1']) || !isset($_POST['val2']) || !isset($_POST['calc'])) {
header("Location: http://127.0.0.1/calculate_form.html");
}
?>

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https://forums.phpfreaks.com/topic/178635-newbie-needs-help/#findComment-942324
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