You should install the build-essential

sudo apt-get install build-essential

after installing this, open a terminal, and type
g++ (hit enter)
if it says there is no input, then you got your g++

even after you installed this, you could still have problems with eclipse cdt
so I really recommend Netbeans, click here.

All you need to do is download Netbeans to your computer, say it's in your Download folder

sudo chmod +x your_download_netbeans.sh

then
./your_download_netbeans.sh

Because you already installed Eclipse on you computer, so I think you've already got jdk installed.