Online PHP htmlentities() function

Convert all applicable characters to HTML entities.
This function is identical to htmlspecialchars() in all ways, except with htmlentities(), all characters which have HTML character entity equivalents are translated into these entities.
If you want to decode instead (the reverse) you can use html_entity_decode().
string htmlentities ( string $string [, int $flags = ENT_COMPAT | ENT_HTML401 [, string $encoding = ini_get("default_charset") [, bool $double_encode = true ]]] )
Hello World!