Essential needs for building chatting program
1. install cmake
=> sudo apt install cmake
2. install gtest
=> sudo apt install libgtest-dev
cd /usr/src/gtest; cmake CMakeLists.txt
make
sudo cp *.a /usr/lib
3. make directory build under server and client.
=> mkdir build
4. generate cmakefile
=> cd build; cmake ..
5. run building
=> make
=> ~/.config/Code/User