How can PHP handle the scenario where certain characters must not be present in a variable received from a form?

To handle the scenario where certain characters must not be present in a variable received from a form, you can use PHP's `preg_replace()` function with a regular expression pattern to remove any unwanted characters. This can help sanitize the input and prevent any potentially harmful characters from being processed further in your application. 

// Get the variable from the form
$variable = $_POST['input_variable'];

// Define the list of characters that are not allowed
$disallowed_chars = '/[&$%#@!]/';

// Remove any disallowed characters from the variable
$clean_variable = preg_replace($disallowed_chars, '', $variable);

// Now $clean_variable is sanitized and can be used safely

Keywords

PHP form handling validation regular expressions character filtering

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