When you use function htmlentities
htmlentities($content, ENT_COMPAT | ENT_HTML401, 'UTF-8');
you might get the error:
Notice: <strong>Use of undefined constant ENT_HTML401 - assumed 'ENT_HTML401'</strong> In ... At Line ...
We know the usage of this function:
string htmlentities ( string $string [, int $flags = ENT_COMPAT | ENT_HTML401 [, string $encoding = ini_get("default_charset") [, bool $double_encode = true ]]] )
To change the encoding, we must set flag, and the default of flag is: ENT_COMPAT | ENT_HTML401
Why the error occur?
Because ENT_HTML401 is only available on PHP 5.4+.
So, we must check php version before use the flag ENT_HTML401
if (version_compare(phpversion(), '5.4', '<')) {
$flags = ENT_COMPAT;
}else{
$flags = ENT_COMPAT | ENT_HTML401;
}
htmlentities($content, $flags, 'UTF-8');
Or you can use:
htmlentities($content, version_compare(phpversion(), '5.4', '<') ? ENT_COMPAT : (ENT_COMPAT | ENT_HTML401), 'UTF-8');
The function works now!
