Difference between htmlentities and htmlspecialchars in PHP

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What is the difference in htmlentities() and htmlspecialchars() function in PHP?

htmlspecialchars() is a subset of htmlentities().

While htmlentities converts “all applicable characters to HTML entities”, htmlspecialchars() only converts …

  • ‘&’ (ampersand) becomes ‘&’
  • ‘”‘ (double quote) becomes ‘"’ when ENT_NOQUOTES is not set.
  • “‘” (single quote) becomes ‘'’ (or ') only when ENT_QUOTES is set.
  • ‘<‘ (less than) becomes ‘&lt;’
  • ‘>’ (greater than) becomes ‘&gt;’

as referenced from the PHP manual.

Both functions are used to perform ‘output escaping’ to make webpage safer against cross-site-scripting attacks.  However, the book Essential PHP Security says …

“htmlentities() is the best escaping function for escaping data to be sent to the client.”

and to use the ENT_QUOTES flag and UTF-8 encoding like this …

htmlentities($userdata, ENT_QUOTES, ‘UTF-8’);

The ENT_QUOTES flag tells it to convert both double and single quotes.

The parameters of the two functions are identical.