<?php 
if ($_SERVER['REQUEST_METHOD'] == "POST" && isset($_POST) && isset($_POST['action'])) { 
    include_once 'Luhn.php'; 
    $luhn = new Luhn(); 
    if ($_POST['action'] == "calculate" && isset($_POST['gnumber'])) { 
        $gnumber = $_POST['gnumber']; 
        $gresult = $luhn->calculate($gnumber); 
    } elseif($_POST['action'] == "validate" && isset($_POST['vnumber'])) { 
        $vnumber = $_POST['vnumber']; 
        if ($luhn->validate(substr($vnumber, 0, -1), substr($vnumber, -1, 1)) == true) { 
            $vresult = "Number is valid"; 
        } else { 
            $vresult = "Number is invalid"; 
        } 
    } 
} 
?><!DOCTYPE html> 
<html> 
<head> 
    <title>Luhn's algorithm</title> 
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 
</head> 
<body> 
    <div> 
        <h1>Check digit calculation</h1> 
        <form method="post"> 
            <input type="hidden" name="action" value="calculate" /> 
            <label for="gnumber">Number </label><input type="text" style="width: 300px;" id="gnumber" name="gnumber" value="<?php if (isset($gnumber)) echo $gnumber; ?>" /><br /> 
            Result <input type="text" style="width: 300px;" disabled="disabled" value="<?php if (isset($gresult)) echo $gresult; ?>" /><br /> 
            <input type="submit" value="Calculate" /> 
        </form> 
        <h1>Number validation</h1> 
        <form method="post"> 
            <p>Number must include check digit - last digit of number is check digit</p> 
            <input type="hidden" name="action" value="validate" /> 
            <label for="vnumber">Number </label><input type="text" style="width: 300px;" id="vnumber" name="vnumber" value="<?php if (isset($vnumber)) echo $vnumber; ?>" /><br /> 
            Result <input type="text" style="width: 300px;" disabled="disabled" value="<?php if (isset($vresult)) echo $vresult; ?>" /><br /> 
            <input type="submit" value="Calculate" /> 
        </form> 
    </div> 
</body> 
</html>
 
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