Are there any best practices to follow when designing a BMI calculator in PHP?

When designing a BMI calculator in PHP, it is important to validate user input to ensure that only numerical values are accepted for height and weight. Additionally, the BMI calculation should be accurate and formatted to display a user-friendly result. It is also recommended to provide clear instructions and error messages for users to understand how to use the calculator correctly. 

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $height = $_POST['height'];
    $weight = $_POST['weight'];

    if (!is_numeric($height) || !is_numeric($weight)) {
        echo "Please enter numerical values for height and weight.";
    } else {
        $bmi = $weight / ($height * $height);
        echo "Your BMI is: " . number_format($bmi, 2);
    }
}
?>

<form method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>">
    <label for="height">Height (m):</label>
    <input type="text" name="height" id="height" required><br><br>
    
    <label for="weight">Weight (kg):</label>
    <input type="text" name="weight" id="weight" required><br><br>
    
    <input type="submit" value="Calculate BMI">
</form>

Keywords

form validation input sanitization mathematical calculations conditional statements user interface

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