So I'm using Code::Blocks right now as my IDE on Windows 10 and I made a small library with one little function.
Code::Blocks made me a .a file.
I then made a little test project that uses the library. Added it to my project build options in Linker Settings, and added its directory to my search directories. Great.
I can see the header file I made for the library so that's working.
I then try to use the function and I'm getting an 'undefined reference' for that function call.
So..I'm going to assume Windows doesn't understand how to load libraries with the '.a' extension? I believe Windows uses .lib files instead but I'm not sure how else I'm supposed to compile a .lib file in Code::Blocks as there's no template for it.
I am extremely new to Code::Blocks and making libraries in general.
Solved. Problem was when renaming the file from "main.c" to "main.cpp", Code::Blocks does not automatically change the compiler variable.
This was done by going into the file properties in the IDE and changing the variable from "CC" to "CPP".
Related
Perhaps I can "create" these necessary files by having them linked to the exe, and store them in a temp folder when the program launches, and if that's possible how please? I've tried messing around with compiler options but nothing seems to work.
In order your executable to not rely on DLL files, you should link them statically. SFML gives you that option by using their "sfml-xxx-s-d.lib" (for Debug) and "sfml-xxx-s.lib" (for Release) libraries, as stated in the documentation.
If you want to get rid of these DLLs and have SFML directly integrated
into your executable, you must link to the static version. Static SFML
libraries have the "-s" suffix: "sfml-xxx-s-d.lib" for Debug, and
"sfml-xxx-s.lib" for Release. In this case, you'll also need to define
the SFML_STATIC macro in the preprocessor options of your project.
NOTE: "xxx" stands for the name of the file you are trying to include into your project
Full documentation on how to set up SFML in VisualStudio: https://www.sfml-dev.org/tutorials/2.5/start-vc.php
Hope this answered your question! :)
I have been programming a game in c++ using the sfml library. However, I would like to adjust some of the code of that library, and use that altered code in my project.
So instead of linking the dll I would like to add the source code and then play with that source code. (e.g. for speed optimization).
I know that doing something like that is generally speaking a bad idea. Howeover, I want to learn by playing around a bit and trying different things.
So how would I add the sfml source code to my c++ project in MS visual studio. Note that I am a total noob. I already tried adding the sfml folder that I downloaded from git in the project properties page called "Additional Include Directories", but i am getting errors, of the form "Cannot open include file: 'SFML/Graphics/GLCheck.hpp': No such file or directory" so I guess that i have not yet done enough.
If you want to modify the source code in the library, all you'd have to do is just navigate to where you have SFML installed and go into the code files with a text editor and edit them.
Then, you could link the library to your VS project the same way you would normally but that library is now modified by you.
Seeing as you have a search directory issue already in VS, you must fix that first. Fix that and then go and modify the library's .hpp, .h, .cpp, whatever files in-place.
To fix the search issue.... I don't use VS for graphics, I use CodeBlocks so I am not sure about their GUI to link libraries and change search directories... but, find out where you installed SFML. Check your /usr/include/, it's probably there. Specify that path in the search directories. Just go and find where that GLCheck.hpp file is located. For Example: Say it's full path is /usr/include/SFML/Graphics/GLCheck.hpp... then /usr/include/SFML/Graphics/ or just /usr/include/ (VS might handle it recursively) needs to be in the list of SEARCH DIRECTORIES.
I just started a tutorial to learn C++ OpenGL using SDL. The steps shown in the videotutorial were done by using the IDE called Code Blocks, but I thought it was going to work also for Visual Studio 2012.
I downloaded the SDL2 developer which is for Windows x64 (my Windows 7 is 64 bits, but the Visual Studio 2012 I have is an x86 version)
To install the SDL2 in Visual Studio 2012, I put:
the .h files in the include folder (D:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\include\SDL).
the .lib files in the lib folder (D:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\lib\SDL).
the .dll file in C:/Windows/system folder.
After that, I opened the IDE, made a new project and while I was writting the code, autocompletion popped up for specific SDL features, meaning success... until I tried to run it.
This is the code I wrote according to the videotutorial:
#include "SDL.h"
int main(int argc, char* args[]){
SDL_Init(SDL_INIT_EVERYTHING);
SDL_Quit();
return 0;
}
When I click on "Start Debugging" or "Start without debugging", after pressing yes to build it, the output comes with errors.
Here's a screenshot of the code I wrote, plus the output:
After that, I tried an older version of the SDL the tutorial was already using, which was the 1.2 (I overwrote few files of the newer version) but still no good results.
How do I fix it so I can practice with OpenGL + SDL features?
TLDR:
When you use a library in your project,
Compiling needs header filenames (#include <*.h>) and include directories containing them
Linking needs lib filenames (*.lib, what you're missing) and library directories containing them
Running needs dynamic libraries (*.dll), commonly using the same name as the .lib in the current or system directory (VS has binary directories too but I've never needed to know what they're for exactly)
When you compile code and add #include <SDL.h>, the compiler runs through a list of possible directories its been given to find that file. There are some default directories already set up, but so you don't have a mess of all your libraries in one place it's possible to add more. For example, Setting Global C++ Include Paths in Visual Studio 2012 (and 2011, and 2010). If your SDL.h is in a subdirectory in an include directory it won't be found - eg. just check this shouldn't be <SDL/SDL.h> or something similar.
With the include path set and the correct #include your code can compile. Now it's the linking stage. You've got some code that says I need the these functions and the linker has to either find the actual code for those functions and link them statically (all the code can be found in the .lib) or set up the program to link at runtime, dynamically (in which case the program needs to be able to find the .dll, and I think on windows you need a .lib file that goes with it).
So in addition to the include directory you need a library directory. Also, just like you said to the compiler #include <SDL.h> you need to tell the linker to look for the code for those functions defined in SDL.h in SDL.lib (which may end up actually providing the code at runtime when loading SDL.dll). I think specifying libraries could even be done through #pragma calls, but it's more common to see the library files specified as arguments to the linker program. As #ScottMcP-MVP said, append SDL.lib to the Project Properties->Configuration Properties->Linker->Input->Additional Dependencies list. If it still says unresolved external that generally means the linker still can't find the file, so check for typos and double check the directories. Worst case is a mismatch between SDL.h and SDL.lib or SDL.lib was compiled with different options or a different compiler.
The error you're receiving is the linker saying the compiler says I need an "external" function, SDL_Init, to make your code work but I haven't found/resolved-the-reference-to one in the list of libraries I've been given.
Just as an example/recap all these GUI options end up going to the compiler/linker. So for example a full compile line might look like this:
./compiler -I/path/to/my/includes -L/path/to/my/lib -lmylibrary.lib mycode.cpp -o myexecutable.exe
Where mycode.cpp contains #include <mylibrary.h>. Note that here the ./compiler is operating as both compiler and linker. The process could be split into:
./compiler -I/path/to/my/includes mycode.cpp -o mycompiledcode.o
./linker -L/path/to/my/lib -lmylibrary.lib mycompiledcode.o -o myexecutable.exe
Once you have your executable it needs to be able to find SDL.dll when you run it. Exactly as you've done, the executable should search the windows system directory. It should also search its current directory. On linux you can set an rpath (not sure on windows). If you keep getting application configuration incorrect and the dll is definitely there it's time to grab dependency walker and see what dll name the program is actually trying to load. Worst case is the application finds a different version of the dll or something else with the same name before the desired one.
Good luck. OpenGL is great fun!!
[EDIT]
You can use either x32 or x64 lib files, but all your code must be the same. It'll probably be easier to start with x32, and if you need fast double computation and more ram then change. OpenGL doesn't have great support for x64 yet so it probably won't make much difference to you.
Additional Dependencies is where you put just "SDL.lib". This file then needs to exist in one of visual studio's library directories. If you don't get unresolved externals from SDL anymore then that part is fixed.
Your _main error is probably to do with a disgusting hack *spit* SDL uses. Straight after #include <SDL.h> put #undef main (may want to surround in #ifdefs in case it changes):
#include <SDL.h> //my include is <SDL2/SDL.h>, as I have both an SDL and SDL2 dir in my include path
#ifdef main
#undef main //remove SDL's main() hook if it exists
#endif
An important thing to note: generally use </> to include external libraries and "/" to include headers within your project - What is the difference between #include <filename> and #include "filename"?
You have to link the lib file into your exe. See Project, Properties, Link, Additional Dependencies. Put the name of the lib file there.
Using netbeans 7.2 and the most recent version of MinGW (using installer) I can't use the libnoise library. I am properly including the header files, the auto completion confirms this, however the library is simply not working. There is a .lib file and a .dll. I have tried every possible combination of adding them under project > properties > Build > Linker as well as putting the .dll in the base project directory. Despite all this I am still getting undefined reference errors whenever I try and run the code. Does anyone know what to do?
I know that it is possible to link import library files (*.lib) with MinGW, but I still suggest to recompile libnoise.
With the current Makefile, this is not very easy and may break. Thus I've written a CMake script, which doesn't only work on Windows, but should work on all CMake supported platforms. In addition to this, I've cleaned up the directory structure. The code itself hasn't been touched and when you build a library it should essentially be the same as the current one.
libnoise on GitHub
After you've built your shared library, you'll have a libnoise.dll.a and libnoise.dll file. You then add libnoise.dll.a to the linking settings and put the DLL itself next to the binary, or in the working directory.
You have to link the lib file (= adding it to linker libraries) and put the dll to
<project root>/dist/<...>/
(where your exe is put to). There's no need to add the dll to linker too.
Can you please post the error message you get?
So I imported this VS9 solution into VS10 and VS10 would convert the whole thing into its new format for solution and project files. However, now it is giving me linker errors.
One project, a native C++ project, is using a set of header files and a .lib file to link to some external library. In the project, this library is specified by being put into a "Library" folder in the project. In VS9, this works fine, in VS10, it fails. The same lib is linked, however, when put into the "Additional Dependencies" setting in the Linker Input panel of the project's options.
I know the technique to drop lib files into the project for more than a decade. Has this stopped working with VS10?
No ,that still works in VS2010 (just tested it to make sure)!