centos7可以直接用yum来安装c++11,而6可以按照以下方式。

CentOS 6.4 使用C++11，需要安装 devtools2

1.下载 repo 到本地

wget http://people.centos.org/tru/devtools-2/devtools-2.repo -O /etc/yum.repos.d/devtools-2.repo

2.安装

yum install devtoolset-2-gcc devtoolset-2-binutils devtoolset-2-gcc-c++

3.创建链接

ln -s /opt/rh/devtoolset-2/root/usr/bin/* /usr/local/bin/

4.设置优先级

update-alternatives --install /usr/bin/gcc gcc /usr/local/bin/gcc 100
update-alternatives --install /usr/bin/g++ g++ /usr/local/bin/g++ 100

5.或者用下面的方法启用

echo 'source /opt/centos/devtoolset-1.1/enable' >> /etc/profile 
source /opt/centos/devtoolset-1.1/enable

其中 3,4,5是保证生效，任选一个应该都可以，我依次做了三个。
还有其它生效方法，如：

scl enable devtoolset-2 bash

In your .bash_profile , add at the bottom:
echo "WARNING: devtoolset-2 is enabled!"
. /opt/rh/devtoolset-2/enable

可以新打开一个终端，gcc -v 和　g++ -v 来查看版本变化

[me@localhost ~]$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/opt/rh/devtoolset-2/root/usr/libexec/gcc/x86_64-redhat-linux/4.8.2/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/opt/rh/devtoolset-2/root/usr --mandir=/opt/rh/devtoolset-2/root/usr/share/man --infodir=/opt/rh/devtoolset-2/root/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --enable-languages=c,c++,fortran,lto --enable-plugin --with-linker-hash-style=gnu --enable-initfini-array --disable-libgcj --with-isl=/dev/shm/home/centos/rpm/BUILD/gcc-4.8.2-20140120/obj-x86_64-redhat-linux/isl-install --with-cloog=/dev/shm/home/centos/rpm/BUILD/gcc-4.8.2-20140120/obj-x86_64-redhat-linux/cloog-install --with-mpc=/dev/shm/home/centos/rpm/BUILD/gcc-4.8.2-20140120/obj-x86_64-redhat-linux/mpc-install --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.8.2 20140120 (Red Hat 4.8.2-15) (GCC) 

[me@localhost ~]$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/opt/rh/devtoolset-2/root/usr/libexec/gcc/x86_64-redhat-linux/4.8.2/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/opt/rh/devtoolset-2/root/usr --mandir=/opt/rh/devtoolset-2/root/usr/share/man --infodir=/opt/rh/devtoolset-2/root/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --enable-languages=c,c++,fortran,lto --enable-plugin --with-linker-hash-style=gnu --enable-initfini-array --disable-libgcj --with-isl=/dev/shm/home/centos/rpm/BUILD/gcc-4.8.2-20140120/obj-x86_64-redhat-linux/isl-install --with-cloog=/dev/shm/home/centos/rpm/BUILD/gcc-4.8.2-20140120/obj-x86_64-redhat-linux/cloog-install --with-mpc=/dev/shm/home/centos/rpm/BUILD/gcc-4.8.2-20140120/obj-x86_64-redhat-linux/mpc-install --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.8.2 20140120 (Red Hat 4.8.2-15) (GCC)