Here is a PHP function that converts millimeters (mm) to inches
<!DOCTYPE html>
<html>
<head>
<title>MM to Inches Conversion</title>
</head>
<body>
<h1>MM to Inches Conversion</h1>
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
Millimeters: <input type="number" name="mm" min="0" step="any">
<input type="submit" value="Convert">
</form>
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// Convert mm to inches
$mm = $_POST["mm"];
$inches = $mm / 25.4;
echo "<p>$mm mm is equal to $inches inches.</p>";
}
?>
</body>
</html>
This code displays a form with a single input field for millimeters. When the user submits the form, the PHP code retrieves the value from the form, converts it to inches, and displays the result on the same page. The htmlspecialchars function is used to sanitize the user input and prevent any potential XSS attacks.