JSON not compiled in php

Question

I installed PHP Version 5.5.1-2 on Ubuntu 12.04 and JSON was not bundled with it (as far as I can tell).

I've read that I will have to reinstall php using the --enable-json or --with-json option.
So my questions are:

How can I verify JSON is not installed?

If not, do I reinstall php like this: apt-get install php --with-json (do I include --enable-json)?

Will my current settings be lost if I reinstall php?

Thanks

Answer 1

If you haven't already installed it:

sudo apt-get install php5-json

(more info: http://iteration99.com/2013/php-json-removed-from-php-5-5/ )

Shouldn't overwrite any other settings.