How to upgrade gcc on CentOS6.5

How to upgrade gcc on CentOS6.5

Question: The default gcc version on CentOS6.5 is too old to build a particular application. How can I upgrade the version of gcc installed on CentOS6.5?

As of CentOS 6.5, the default version of gcc installed is 4.4.7. If you want to upgrade gcc on CentOS, you can install devtools, which is a CentOS version of Red Hat Developer Toolset. The devtools, which is available for CentOS 5 and 6, contains a suite of development tools including gcc, gdb, binutils, elfutils, etc. The devtools 1.1. offers gcc version 4.7.2.

To install devtools on CentOS, use the following commands.

$ sudo wget http://people.centos.org/tru/devtools-1.1/devtools-1.1.repo -P /etc/yum.repos.d
$ sudo sh -c 'echo "enabled=1" >> /etc/yum.repos.d/devtools-1.1.repo'
$ sudo yum install devtoolset-1.1

devtools will be installed under /opt/centos/devtoolset-1.1.

To use gcc from devtoolset, use the following command. This command will launch a new shell, wherein all environment variables are automatically set to use devtools.

$ scl enable devtoolset-1.1 bash
$ gcc --version

Alternatively, you can explicitly define the following variables to use devtools.

export CC=/opt/centos/devtoolset-1.1/root/usr/bin/gcc  
export CPP=/opt/centos/devtoolset-1.1/root/usr/bin/cpp
export CXX=/opt/centos/devtoolset-1.1/root/usr/bin/c++

參考：
http://ask.xmodulo.com/upgrade-gcc-centos.html