htmlentities vs htmlspecialchars

Question

What are the differences between htmlspecialchars and htmlentities. When should I use one or the other?

Answer 1

From the PHP documentation for htmlentities:

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.

From the PHP documentation for htmlspecialchars:

Certain characters have special significance in HTML, and should be represented by HTML entities if they are to preserve their meanings. This function returns a string with some of these conversions made; the translations made are those most useful for everyday web programming. If you require all HTML character entities to be translated, use htmlentities() instead.

The difference is what gets encoded. The choices are everything (entities) or "special" characters, like ampersand, double and single quotes, less than, and greater than (specialchars).

I prefer to use htmlspecialchars whenever possible.

Answer 2

You probably want to use some Unicode character encoding, for example utf-8, and htmlspecialchars. Because there is no need to generate "HTML entities" for "all [the] applicable characters" (that is what htmlentities does according to the documentation) if it's already in your character set.