Installation

First you should download and install ICU:

Example #1 install ICU on Unix

./configure --disable-threads --enable-extras --enable-icuio --enable-layout
make && make install

Then checkout latest PHP and configure it --with-icu-dir=<dir> option, where <dir> was the dir to where you installed ICU. You don't need to explicitly use this option if you install ICU to a standard location.