March 25, 2012
How to write a PHP code on simple math expression?
Question by user1290968
I am a newbie of PHP coding, and want to do a simple math example, d=(a+b)/c.
The values of a and b will be submitted by the user from a webpage containing PHP form.
The value of c is predefined in the PHP page.
When the user click “submit” in this webpage.
I expect to get the result of d in the bottom of the same webpage.
Any example code will be greatly appreciated.
Answer by ocanal
<form method="POST" action="">
<input type="hidden" id="c" name="c" value="10" />
<label for="a">a: </label>
<input type="text" id="a" name="a" /> <br />
<label for="b">b: </label>
<input type="text" id="b" name="b" />
<input type="submit" />
</form>
<br />
<?php
if (isset($_POST["a"]) && isset($_POST["b"]) && isset($_POST["c"])) {
if (is_numeric($_POST["a"]) && is_numeric($_POST["b"]) && is_numeric($_POST["c"])) {
$d = ($_POST["a"] + $_POST["b"])/$_POST["c"];
echo "d = ". $d;
} else {
echo "all values must be numeric!"
}
}
?>
Answer by Starx
It is not that different from other languages. Assuming you are using POST to submit the form.
$d = ($_POST['a'] + $_POST['b'])/$c;
WARNING: Injection Vulnerability if used in SQL query. But shouldn’t be a problem while learning.
To display the result. Use echo statement, which prints out the text/variable to the browser.
<?PHP echo $d; ?>
Place this snippet, where you want to display.
For example:
<div> Here is the result: <?PHP echo $d; ?> </div>
