What are some potential pitfalls of using htmlspecialchars() in PHP to check for special characters in a string?

Using htmlspecialchars() to check for special characters in a string can be misleading as it is primarily used to escape HTML entities for output on a webpage, not for checking the presence of special characters. To properly check for special characters in a string, it's better to use a regular expression or a function specifically designed for that purpose, such as preg_match(). This will ensure that the check is accurate and reliable. 

// Checking for special characters in a string using preg_match()
$string = "Hello!@#$%^&*";
if (preg_match('/[\'^£$%&*()}{@#~?><>,|=_+¬-]/', $string)) {
    echo "Special characters found in the string.";
} else {
    echo "No special characters found in the string.";
}

Keywords

htmlspecialchars special characters string encoding security

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