[Reship] How to install and use GCC g++ v4.7 and C++11

Step 1. Install the operating system.

You can download the current version ubuntu on the web-site "http://cdimage.ubuntu.com/daily-live/current/".

Step 2. Make sure the meta-package named "build-essential" has been install correct in the ubuntu system.

$ sudo apt-get install build-essential

Step 3. Add the necessary PPA on the ubuntu system.

A quick search on Google turned up a PPA with the newer GCC v4.7, which has support for nearly all the new C++11 features. Add this PPA with the following commands:

$ sudo add-apt-repository ppa:ubuntu-toolchain-r/test
$ sudo apt-get update

Step 4. Install the GCC v4.7 C/C++ compilers.

$ sudo apt-get install gcc-4.7 g++-4.7

Step 5. Switching compilers.

Installing the v4.7 compilers does not remove the previous version compiler. This is very important, if you skipped the previous sentence, now is a good time to go back and re-read it! The system now has 2 'C' compilers and 2 'C++' compilers:

$ which g++
/usr/bin/g++
$ ls -lh /usr/bin/g++
lrwxrwxrwx 1 root root 7 Dec 12 17:04 /usr/bin/g++ -> g++-4.6
$ ls -lh /usr/bin/g++*
lrwxrwxrwx 1 root root 7 Dec 12 17:04 /usr/bin/g++ -> g++-4.6
-rwxr-xr-x 1 root root 349K Dec 17 04:17 /usr/bin/g++-4.6
-rwxr-xr-x 1 root root 566K Dec 22 02:37 /usr/bin/g++-4.7

Luckily, there is a very simple and standard method for switching between applications that provide identical (or near-identical) functionality: update-alternatives. If you've never had to use this before, go ahead and run man update-alternatives.

We need to let update-alternatives know we have 2 C/C++ compilers, create a record for each one, and then configure which one we want to use. This is done with the following:

$sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.6 60 --slave /usr/bin/g++ g++ /usr/bin/g++-4.6
$sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.7 40 --slave /usr/bin/g++ g++ /usr/bin/g++-4.7
$sudo update-alternatives --config gcc

Note the use of "slave". This ensures when we change the configuration for gcc, that we automatically update the configuration for g++. This is important so the compilers aren't out-of-sync.

From this point forward, the only thing required when switching compilers is this (relatively) simple command:

$sudo update-alternatives --config gcc

Calling the C++ compiler with --version confirms the right version is correctly installed:

$ g++ --version
g++ (Ubuntu/Linaro 4.7-20111222-0ubuntu1) 4.7.0 20111222 (experimental) [trunk revision 182617]

Step 6. Test the compilers.

I will not say anything about it. The reader can code and test the C++11 features himself.

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