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Thread: Problems compiling "Hello World" (C++) in Ubuntu 12.10 using CodeBlocks

  1. #1
    Join Date
    Mar 2013
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    5

    Problems compiling "Hello World" (C++) in Ubuntu 12.10 using CodeBlocks

    Hi

    I have finished installing Ubuntu 12.10 and CodeBlocks from the Software Center. I haven't worked with Linux before. I have the following C++ script in CodeBlocks:

    Code:
    #include <iostream>
    
    using namespace std;
    
    int main()
    {
        cout << "Hello world!" << endl;
        return 0;
    }
    When I press F9 (build and run), CodeBlocks gives me the message:

    ||=== asd, Debug ===|
    obj/Debug/main.o||In function `main'
    /home/niles/asd/main.cpp|7|undefined reference to `std::cout'|
    /home/niles/asd/main.cpp|7|undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std:perator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'|
    /home/niles/asd/main.cpp|7|undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)'|
    /home/niles/asd/main.cpp|7|undefined reference to `std:stream:perator<<(std:stream& (*)(std:stream&))'|
    obj/Debug/main.o||In function `__static_initialization_and_destruction_0'
    /usr/include/c++/4.7/iostream|75|undefined reference to `std::ios_base::Init::Init()'|
    /usr/include/c++/4.7/iostream|75|undefined reference to `std::ios_base::Init::~Init()'|
    ||=== Build finished: 6 errors, 0 warnings ===|

    The compiler is g++. I don't really understand what is going on, the namespace is correct. Thanks for any help in advance.

  2. #2
    Join Date
    Jun 2007
    Location
    Maryland, US
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    6,268
    Distro
    Kubuntu

    Re: Problems compiling "Hello World" (C++) in Ubuntu 12.10 using CodeBlocks

    Does this look familiar... from the command line:
    Code:
    $ gcc foo.cpp 
    /tmp/ccMeBXOS.o: In function `main':
    foo.cpp:(.text+0xa): undefined reference to `std::cout'
    foo.cpp:(.text+0xf): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
    foo.cpp:(.text+0x14): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)'
    foo.cpp:(.text+0x1c): undefined reference to `std::basic_ostream<char, std::char_traits<char> >::operator<<(std::basic_ostream<char, std::char_traits<char> >& (*)(std::basic_ostream<char, std::char_traits<char> >&))'
    /tmp/ccMeBXOS.o: In function `__static_initialization_and_destruction_0(int, int)':
    foo.cpp:(.text+0x4a): undefined reference to `std::ios_base::Init::Init()'
    foo.cpp:(.text+0x4f): undefined reference to `std::ios_base::Init::~Init()'
    collect2: ld returned 1 exit status
    CodeBlocks is using 'gcc', not 'g++.

  3. #3
    Join Date
    Mar 2013
    Beans
    5

    Re: Problems compiling "Hello World" (C++) in Ubuntu 12.10 using CodeBlocks

    Quote Originally Posted by dwhitney67 View Post
    Does this look familiar... from the command line:
    Code:
    $ gcc foo.cpp 
    /tmp/ccMeBXOS.o: In function `main':
    foo.cpp:(.text+0xa): undefined reference to `std::cout'
    foo.cpp:(.text+0xf): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
    foo.cpp:(.text+0x14): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)'
    foo.cpp:(.text+0x1c): undefined reference to `std::basic_ostream<char, std::char_traits<char> >::operator<<(std::basic_ostream<char, std::char_traits<char> >& (*)(std::basic_ostream<char, std::char_traits<char> >&))'
    /tmp/ccMeBXOS.o: In function `__static_initialization_and_destruction_0(int, int)':
    foo.cpp:(.text+0x4a): undefined reference to `std::ios_base::Init::Init()'
    foo.cpp:(.text+0x4f): undefined reference to `std::ios_base::Init::~Init()'
    collect2: ld returned 1 exit status
    CodeBlocks is using 'gcc', not 'g++.

    I just double-checked, and my CodeBlocks is set to use g++ for C++, gcc for C.

  4. #4
    Join Date
    Jun 2007
    Location
    Maryland, US
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    6,268
    Distro
    Kubuntu

    Re: Problems compiling "Hello World" (C++) in Ubuntu 12.10 using CodeBlocks

    Check you system to ensure that you do indeed have 'g++' installed.
    Code:
    sudo apt-get install g++
    If it is installed, then I suppose it's a CodeBlock issue.

  5. #5
    Join Date
    Mar 2006
    Beans
    837

    Re: Problems compiling "Hello World" (C++) in Ubuntu 12.10 using CodeBlocks

    Maybe CodeBlocks thinks that this is a C source file and tries to compile it with gcc. Somewhere in the project settings you should be able to switch it to C++.

  6. #6
    Join Date
    Mar 2013
    Beans
    5

    Re: Problems compiling "Hello World" (C++) in Ubuntu 12.10 using CodeBlocks

    Quote Originally Posted by dwhitney67 View Post
    Check you system to ensure that you do indeed have 'g++' installed.
    Code:
    sudo apt-get install g++
    If it is installed, then I suppose it's a CodeBlock issue.
    I tried this and it says "g++ is already the newest version"




    Quote Originally Posted by SledgeHammer_999 View Post
    Maybe CodeBlocks thinks that this is a C source file and tries to compile it with gcc. Somewhere in the project settings you should be able to switch it to C++.
    Good point. I solved the problem: The linker was set to GCC, but I changed in to g++ (the C++ compiler was already g++). It works now, thanks to both of you.

    Best,
    Niles.

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