Here is How To Install Doxygen in Ubuntu 18.04. Just copy and paste the commands below into your Ubuntu terminal to get this package.
What is Doxygen?
Doxygen is a documentation system for C, C++, Java, Objective-C, Python, IDL and to some extent PHP, C#, and D. It can generate an on-line class browser (in HTML) and/or an off-line reference manual (in LaTeX) from a set of documented source files. There is also support for generating man pages and for converting the generated output into Postscript, hyperlinked PDF or compressed HTML. The documentation is extracted directly from the sources.
How To Install Doxygen in Ubuntu?
Update your system first then install the Doxygen Package in your Ubuntu os. Open your Ubuntu terminal and just copy and paste these commands:
sudo apt update sudo apt install doxygen
If you want to do it forcefully then use these commands
sudo apt update -y sudo apt install doxygen -y