Now you have the gcc 4.8 with c++11 complete feature in your system. Check out by:

gcc --version

gcc (Ubuntu 4.8.1-2ubuntu1~13.04) 4.8.1
Copyright (C) 2013 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

I'm a freelance blogger who started using Ubuntu 5+ years ago and wishes to share my experiences and some useful tips with Ubuntu beginners and lovers. Please notify me if you find any typo/grammar/language mistakes. English is not my native language. Contact me on Google Plus or email to ubuntuhandbook1@gmail.com

Thank you very much. I have Ubuntu 12.04.2 32-bit and it worked flawlessly. I have installed Eclipse Kepler (version 4.3) and the first time I compiled a program it compiled it without any problems. When I tried to execute it, Eclipse showed me a panel where I have to chose the program to execute, showing me two alternatives, the second one with the suffix x64. I looked at the binaries folder and it appeared the compilation generated two versions, one for x86 (32-bit) and the other for x64 (64-bit). Of course, choosing the x64 version of the program to execute generated an error. When I choose the x32 version, the program executed without a glitch. When I tried to compile and execute a second program g++ did not generate the x64 version anymore. Now that I know this procedure works I am going to install it in my Ubuntu 12.04.3 64-bit, which I have installed separately in the same machine.

Referring to my previous message, I want to signal some bizarre things that eventhough are not giving errors in the compilation or execution of C, C++ programs it is convenient to have an explanation because they are annoying. After I installed the gcc and g++ version 4.8.1-2 I saw the Update Manager telling me that there were:
BEGIN QUOTE
“Other udpates (LP-PPA-ubuntu-toolchain-r-test)”. Those updates refer to:
GNU C preprocessor cpp-4.6
GNU C++ compiler g++-4.6
GNU C compiler gcc-4.6
GCC, the GNU Compiler Collection (base package) gcc-4.6-base
GNU Standard C++ Library v3 (development files) libstdc++6.4.6-dev
Installed version: 4.6.3-1ubuntu5
Available version: 4.6.4-1ubuntu1~12.4
END OF QUOTE

So I decide to reboot the machine. However, the same message above appears again. It is like Ubuntu does not realize that now gcc and g++ are in version 4.8.1-2.