Winston provides some information on running C++ under Unix. Use "g++" where he uses "CC", and use ".cpp" as the C++ source code file extension.
Check out the CAEN technical note C/C++ Programming on the Unix Platform, which includes these instructions for accessing g++ on CAEN:
The gcc and g++ compilers are GNU utilities; you will need to run swselect to enable them in your shell environment. Choose GNU Compilers/Utils. After you exit swselect, be sure to type source ~/.software to make the change immediate.