Need a good guide g++ on how to compile code

This is a discussion on Need a good guide g++ on how to compile code within the C++ Programming forums, part of the General Programming Boards category; I'm wokring on a project and there are a lot of different libraries that I need to link to (.a ...

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    Need a good guide g++ on how to compile code

    I'm wokring on a project and there are a lot of different libraries that I need to link to (.a files). I am including these header files in my code, and I really have no idea how I'm supposed to do all of this.

    Does anyone know of a good guide (with lots of examples) on how to do this?

    Thanks!

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    Any ideas? I just need to know the different phases, etc.

    For example, if I link to a .a file, to I need to include the header in with the -I flag? These things I don't know.

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    and the Hat of Guessing tabstop's Avatar
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    You never include headers with an -I flag; that's not what it's for. Have you read the manual? Do you know what "compiling" and "linking" and "libraries" mean, as words in this context?

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    Quote Originally Posted by tabstop View Post
    You never include headers with an -I flag; that's not what it's for. Have you read the manual? Do you know what "compiling" and "linking" and "libraries" mean, as words in this context?
    I'm not very familiar with those terms. I guess I can look at the manual, but I was hoping for more of a tutorial. I feel like what I'm doing is pretty basic. I have my own .h and .c files and am building a wrapper around an existing library, that's been compiled as a .a...

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    a_capitalist_story
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    Have you tried typing the words g++ tutorial into a search engine?

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    Quote Originally Posted by rags_to_riches View Post
    Have you tried typing the words g++ tutorial into a search engine?
    yes, they just give pretty basic tutorials discussing -Wall and stuff. I need something a little more robust.

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    and the hat of int overfl Salem's Avatar
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    There are only three relevant options you need worry about for additional libraries

    -I for specifying where the pre-processor should look for .h files.
    -L for specifying where the linker should look for .a files.
    -l for specifying which .a files (the linker) should search in.

    As for the names of .h files to #include in the source, and the names of the .a files to pass to the linker, well that's just down to reading the manual for each library you want to use.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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    Quote Originally Posted by Salem View Post
    There are only three relevant options you need worry about for additional libraries

    -I for specifying where the pre-processor should look for .h files.
    -L for specifying where the linker should look for .a files.
    -l for specifying which .a files (the linker) should search in.

    As for the names of .h files to #include in the source, and the names of the .a files to pass to the linker, well that's just down to reading the manual for each library you want to use.
    ok, so when do I specify the -I, the -L, etc?

    I just need a general tutorial that explains this stuff, the different phases, what they mean, etc. I find it hard that people just automatically know this stuff....

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    for a given file main.cpp, in a directory dir, if all the .h files are also in the directory "dir", do I need to specify those via -I? These things I have no idea. How do I specify the location of my .a file? things like that.

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    Ok, so if I'm linking to a .a file, when I do the -I phase, I don't need to specify .a's header files?

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    a_capitalist_story
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    You really need to learn how to use a search engine, but I'll spoon feed you I guess: GCC tutorial - An Introduction to GCC

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    Quote Originally Posted by rags_to_riches View Post
    You really need to learn how to use a search engine, but I'll spoon feed you I guess: GCC tutorial - An Introduction to GCC
    I saw that. It's $20. I figured there'd be something else out there.

    I've found some, actually, thanks.

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    'man gcc'
    Or if you're not on a linux/unix system:
    Directory Options - Using the GNU Compiler Collection (GCC)
    Link Options - Using the GNU Compiler Collection (GCC)

    Quote Originally Posted by dayalsoap View Post
    for a given file main.cpp, in a directory dir, if all the .h files are also in the directory "dir", do I need to specify those via -I?
    No, if all the header files are in the same dir as the source file you don't need -I if you use "file.h" for your #includes instead of <file.h>
    Or if your header files are in 'dir/some_subdir' you can use
    #include "some_subdir/file.h"
    in your source file to avoid needing to use -I

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    a guy with long hair Xupicor's Avatar
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    As was mentioned, you should read relevant README files, man entries or online help sources for your libraries to see what files and in what order you should link to. If your .a files are in the usual "include" directory, then you generally do: "gcc main.c -lgmp -lcurl" etc. You can also see NetBeans C/C++ build logs - add some libraries trough project options first and see how things are being compiled, when the linking takes place.

    People don't usually know these things automatically, but there are search engines that happen to help, documentations... I find it difficult to believe that you don't quite know how to work with headers and libraries and you get to work on a project with "a lot of different libraries" out of the blue.

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    Quote Originally Posted by dayalsoap View Post
    Does anyone know of a good guide (with lots of examples) on how to do this?
    Developers usually provide how-to's compile and link their libraries, but in case of C++ it differs from project to project. I cannot imagine how the supposed examples would look like, "here you got 3 .a libraries, using the mentioned GNU linker link them together into an .exe".
    I never put signature, but I decided to make an exception.

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