Não é possível instalar o g ++ Ubuntu 14.04.3

Question

Eu tentei "sudo apt-get install g ++" Eu tenho uma longa seqüência de

qtdeclarative5-qtfeedback-plugin is already the newest version.
gnome-power-manager is already the newest version.

Terminando em:     0 atualizado, 0 recém-instalado, 0 para remover e 0 não atualizado.

No entanto, quando eu volto tentando executar um programa "g ++ -o Hello Hello.cpp", mas recebo o

The program 'g++' is currently not installed. You can install it by typing:
   sudo apt-get install g++

EDITAR:

apt-cache policy g++-4.8

    g++-4.8:
      Installed: (none)
      Candidate: 4.8.2-19ubuntu1
      Version table:
         4.8.2-19ubuntu1 0
            500 http://gr.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages

sudo apt-get install g++-4.8

    Reading package lists... Done
    Building dependency tree       
    Reading state information... Done
    Some packages could not be installed. This may mean that you have
    requested an impossible situation or if you are using the unstable
    distribution that some required packages have not yet been created
    or been moved out of Incoming.
    The following information may help to resolve the situation:

    The following packages have unmet dependencies:
     g++-4.8 : Depends: gcc-4.8-base (= 4.8.2-19ubuntu1) but 4.8.4-2ubuntu1~14.04 is to be installed
               Depends: gcc-4.8 (= 4.8.2-19ubuntu1) but 4.8.4-2ubuntu1~14.04 is to be installed
               Depends: libstdc++-4.8-dev (= 4.8.2-19ubuntu1) but it is not going to be installed
    E: Unable to correct problems, you have held broken packages.

    

Answer 1

De acordo com as atualizações da sua pergunta, você desativou o repositório de atualizações confiáveis

Abra o Software & amp; Atualizações , abra a aba Atualizações e ative a caixa de seleção para Atualizações recomendadas

Agora instale o pacote novamente

sudo apt-get install g++