Removing specific html characters from a string

Question

Its a bit tricky situation. I have a form for users to input their comments. Sometimes, users put in HTML characters. My problem is, I just want to save specific HTML characters like bold, table, tr, td with <> tags. Except this any other HTML characters should be removed from the string. I would like to know how to do this??

Answer 1

strip_tags allows you set list of allowable tags.

string strip_tags ( string $str [, string $allowable_tags ] )

echo strip_tags($text, '<b><table><tr><td>');