Ubuntu – Why can’t I install g++

compilingg++installation

while trying to compile a program with the following command:
g++ -o <output_file> <my_file.cpp>

I found the following report….

The program 'g++' can be found in the following packages:
 * g++
 * pentium-builder
 Try: sudo apt-get install <selected package>

Then I tried…

nawshad@ubuntu:~/Thesis/Codes/Thesis_Utility_Function/Test Codes$ sudo apt-get   install   g++
Reading package lists... Done
Building dependency tree       
Reading state information... Done
You might want to run 'apt-get -f install' to correct these:
The following packages have unmet dependencies:
 g++ : Depends: g++-4.6 (>= 4.6.3-1~) but it is not going to be installed
 libqt4-opengl : Depends: libqtcore4 (= 4:4.8.1-0ubuntu4.1) but 4:4.8.1-0ubuntu4 is to be installed
                 Depends: libqtgui4 (= 4:4.8.1-0ubuntu4.1) but 4:4.8.1-0ubuntu4 is to be installed
 libqt4-svg : Depends: libqtcore4 (= 4:4.8.1-0ubuntu4.1) but 4:4.8.1-0ubuntu4 is to be installed
              Depends: libqtgui4 (= 4:4.8.1-0ubuntu4.1) but 4:4.8.1-0ubuntu4 is to be installed
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

But cant install due to unmet dependencies.

Best Answer

Run:

sudo apt-get update

You should always run that before installing or upgrading packages on the command-line (unless you've run it very recently). It fetches information about what packages are available in what versions from where.

You may simply be able to install g++ now, but go ahead and do as Web-E says (after running the above command), to fix any currently broken dependencies:

sudo apt-get -f install

(The -f can actually go before or after the install; the effect is the same.)

Then try installing g++ again:

sudo apt-get install g++

If that still fails, please edit your question to show any error messages (and also the output of the above two commands when you ran them). But it should succeed.

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