What is the purpose of using preg_match in PHP and how can it be used to limit font sizes within a specific range?

When working with user input in PHP, it's important to validate and sanitize the data to prevent any security vulnerabilities or unexpected behavior. One common use case is limiting font sizes within a specific range to ensure consistency and prevent malicious input. To achieve this, we can use the preg_match function in PHP to check if the font size provided by the user falls within the desired range. By using a regular expression pattern, we can validate the input and only allow font sizes that meet our criteria.

// Validate font size within a specific range
$font_size = $_POST['font_size'];

if (preg_match('/^\d+$/', $font_size) && $font_size >= 10 && $font_size <= 20) {
    // Font size is valid and within the range
    echo "Font size is valid: " . $font_size;
} else {
    // Font size is not valid or outside the range
    echo "Font size must be a number between 10 and 20.";
}