What common mistakes are users making when trying to validate form input using PHP?

One common mistake users make when trying to validate form input using PHP is not properly sanitizing user input before validating it. This can leave the application vulnerable to SQL injection attacks. To solve this issue, always sanitize user input using functions like htmlspecialchars() or mysqli_real_escape_string() before validating it. 

// Sanitize user input before validating
$input = $_POST['input'];
$sanitized_input = htmlspecialchars($input);

// Validate the sanitized input
if (empty($sanitized_input)) {
    echo "Input is empty";
} else {
    // Proceed with further validation or processing
}

Keywords

empty() isset() htmlspecialchars() filter_var() validation

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