The stringi package depends on the ICU4C >= 50 library.
If you build the package from sources and either:

* these requirements are not met (check out http://site.icu-project.org/download
   or e.g. the `libicu-devel` rpm package on Fedora or `libicu-dev` on Ubuntu),

* `pkg-config` is not able to find proper build settings for ICU-based projects,
or

* R CMD INSTALL is called with `--configure-args='--disable-pkg-config'`,

then the library will be built together with stringi
(a custom subset of ICU4C 52.1 is shipped with the package).


You are encouraged to check whether the ICU data library (`icudt`)
has been successfully installed by calling:

    > library('stringi')
    > stri_install_check()

This will also make you sure that ICU has detected your locale and native
encoding properly.