Doing Calculations in a Form

gr3gg0r

What i want to know how to do is have a user input a number (or any kind of data) in one line or the other of a form, then when they hit the submit button, i want it to do a calculation on the number, and output the final result in the other line of the form. A common example would be a farenheit to celcius converter. Thanks for reading!

devinemke

<?php
if (isset($_POST['num'])) {$num = $_POST['num'];}
else {$num = '';}

if (isset($_POST['submit']) && $_POST['num']) {$numx2 = $_POST['num'] * 2;}
else {$numx2 = '';}
?>

<form action="" method="POST">
number: <input type="text" name="num" value="<?php echo $num; ?>">
<input type="submit" name="submit" value="double it"><br>
number x 2: <input type="text" name="numx2" value="<?php echo $numx2; ?>"><br>
</form>

gr3gg0r

that is really quite excellent, and helps me tremendously, however, i need it to be able to go both ways. In the example you gave me, i would also need to be able to enter a value in the second box, and it woud divide it in half and place the result in the first box. Thanks though, i really do appriciate your help

devinemke

<?php 
if (isset($_POST['num1'])) {$num1 = $_POST['num1'];} 
else {$num1 = '';}

if (isset($_POST['num2'])) {$num2 = $_POST['num2'];} 
else {$num2 = '';}

if (isset($_POST['submit']))
{
	if ($_POST['submit'] == 'x 2') {$num2 = $num1 * 2;}
	if ($_POST['submit'] == '/ 2') {$num1 = $num2 / 2;}
} 
?> 

<form action="" method="POST"> 
number 1: <input type="text" name="num1" value="<?php echo $num1; ?>"> 
<input type="submit" name="submit" value="x 2"><br> 
number 2: <input type="text" name="num2" value="<?php echo $num2; ?>">
<input type="submit" name="submit" value="/ 2"><br> 
</form>