Install libunistring-dev by entering the following commands in the terminal:
sudo apt update sudo apt install libunistring-dev
Description:
Unicode string library for C - development files
The 'libunistring' library implements Unicode strings (in the UTF-8, UTF-16, and UTF-32 encodings), together with functions for Unicode characters (character names, classifications, properties) and functions for string processing (formatted output, width, word breaks, line breaks, normalization, case folding, regular expressions). . This package contains the development support files needed to compile and link against libunistring, as well as the documentation in Info and HTML format.
Homepage: http://www.gnu.org/software/libunistring/
Version: 0.9.9-0ubuntu1
Section: libdevel