g++ is often necessary for building various packages. But It’s quite hard to install it in CentOS if you don’t know a simple thing: yum install g++ will not work here. yum install compat-g++and yum install gcc-g++ won’t give any result too. The only command for yum to install g++ on CentOS is the following:
yum install gcc-c++
You might also want to install it with some more useful packages. Then your command will be:
yum install gcc-c++ compat-gcc-32 compat-gcc-32-c++
Hope this helps you to install g++ under CentOS.