I'm trying to compile this code:
#include "SDL/SDL.h"
int main(void) {
SDL_Surface *Hello = NULL;
SDL_Surface *Screen = NULL;
SDL_Init( SDL_INIT_EVERYTHING );
return 0;
}
But it happens that the compiler says that:
undefined reference to SDL_Init
I dont know why this is happening. I'm using Debian Mint and Code::Blocks. Could you Help me?
It looks like you haven't got -lSDL on your link line.
sdl-config returns the compile and link flags for your installation of SDL.
Assuming the program is sdl.cpp
g++ -o sdl `sdl-config --cflags` sdl.cpp `sdl-config --libs`
Should give you the correct flags.
Go to project and then build options and select your project name.
Now go to the linker setting and type the following lines in the Other Linker options textbox:
-lSDLmain
-lSDL
SDL also requires command line arguments in the main function so you should change
int main(void)
to
int main(int argc, char **argv)
Now compile your project and it should work.
Related
I installed the MinGW version of SDL from their website.
I created a sample piece of code just to test if I could include the library without any errors.
#include <iostream>
#include <SDL.h>
using namespace std;
int main(int argc, char* argv[]) {
if(SDL_Init(SDL_INIT_VIDEO) < 0) {
cout << "SDL INIT FAILED" << endl;
return 1;
}
cout << "SDL INIT SUCCEEDED" << endl;
SDL_Quit();
return 0;
}
I also created a Makefile:
#OBJS specifies which files to compile as part of the project
OBJS = main.cpp
#CC specifies which compiler we're using
CC = g++
#INCLUDE_PATHS specifies the additional include paths we'll need
INCLUDE_PATHS = -Isrc\includes
#LIBRARY_PATHS specifies the additional library paths we'll need
LIBRARY_PATHS = -Lsrc\lib
#COMPILER_FLAGS specifies the additional compilation options we're using
# -w suppresses all warnings
# -Wl,-subsystem,windows gets rid of the console window
COMPILER_FLAGS = -w -Wl,-subsystem,windows
#LINKER_FLAGS specifies the libraries we're linking against
LINKER_FLAGS = -lmingw32 -lSDL2main -lSDL2
#OBJ_NAME specifies the name of our exectuable
OBJ_NAME = main
#This is the target that compiles our executable
all : $(OBJS)
$(CC) $(OBJS) $(INCLUDE_PATHS) $(LIBRARY_PATHS) $(COMPILER_FLAGS) $(LINKER_FLAGS) -o $(OBJ_NAME)
If I don't include the int argc, char* argv[] inside of int main() and try to ming32-make, it throws an error:
C:\Users\username\Documents\Projects\C++\SDL_test> mingw32-make
g++ main.cpp -Isrc\includes -Lsrc\lib -w -Wl,-subsystem,windows -lmingw32 -lSDL2main -lSDL2 -o main
c:/mingw/bin/../lib/gcc/x86_64-w64-mingw32/11.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: src\lib/libSDL2main.a(SDL_windows_main.o): in function `main_getcmdline':
/Users/valve/release/SDL2/SDL2-2.26.2-source/foo-x64/../src/main/windows/SDL_windows_main.c:82: undefined reference to `SDL_main'
collect2.exe: error: ld returned 1 exit status
mingw32-make: *** [Makefile:26: all] Error 1
When I include int argc, char* argv[], it doesn't give any errors but doesn't print anything either.
C:\Users\username\Documents\Projects\C++\SDL_test> mingw32-make
g++ main.cpp -Isrc\includes -Lsrc\lib -w -Wl,-subsystem,windows -lmingw32 -lSDL2main -lSDL2 -o main
C:\Users\username\Documents\Projects\C++\SDL_test>
When I use make instead of mingw32-make, the output remains the same.
I am using VSCode and I have included the header files and lib files in an src folder in the same directory as my script and also moved the SDL2.dll file in the root folder:
My C++ Configuration on VSCode:
Compiler Path: C:\MinGW\bin\g++.exe
Compiler Arguments:
IntelliSense mode: gcc-x64 (legacy) // Because using anything else says the the mode is incompatible with the compiler path.
Include path:
${workspaceFolder}/**
${workspaceFolder}/src/includes
I had also recieved SDL.h: file or directory not found errors before this and I fixed them by creating the Makefile.
Is there something I'm missing? Does SDL not output to stdout, because I've seen tutorials online and they are able to get outputs from cout fine on them.
I am expecting cout to work when I run the script.
-Wl,-subsystem,windows (aka -mwindows) hides the console window, and with it all output. Remove it, and use it only in the release builds.
-w suppresses all warnings
This is extremely unwise. Prefer -Wall -Wextra -Wdeprecated to enable most common warnings, plus -std=c++20 -pedantic-errors to enforce standard compliance (replace 20 with the latest version supported by your compiler).
As suggested by #keltar, you might be able to get output even from a program built with -mwindows if you redirect it to a file, using my_program.exe >output.txt.
EDIT: The issue was that I hadn't installed SDL2 the right way. I installed MSYS2 and used it to install MinGW-w64.
I then used the Msys2 command-line interface to install SDL2 using these commands:
pacman -Syu
pacman -Su
pacman -S mingw-w64-x86_64-SDL2
This installed the header and lib files for SDL in their proper locations. I was then able to include those files in my code.
I changed the main function from int main(int argc, char* argv[]) to int WinMain(int argc, char* argv[]) because I'm on Windows and this helps get rid of the undefined reference to WinMain error.
My working code:
#include <iostream>
#include <SDL2/SDL.h>
using namespace std;
int WinMain(int argc, char* argv[]) {
if(SDL_Init(SDL_INIT_VIDEO) < 0) {
cout << "SDL INIT FAILED" << endl;
return 1;
}
cout << "SDL INIT SUCCESSFUL" << endl;
}
I would like to develope an application using C++ and OpenGL for Windows 64bit.
I am using the following Compiler x86_64-w64-mingw32-g++.
The following code snippet (Test.cpp) is sufficient to trigger the error I get:
#include <GL/gl.h>
int main(int argn, char **argv) {
glClear(GL_COLOR_BUFFER_BIT);
}
(I know this code is meaningless, but it is sufficient to trigger the error during linking.)
I use the following Makefile:
Test:
g++ -lopengl32 -o Test Test.cpp
This yields the following error:
undefined reference to `__imp_glClear'
I have no clue what I am missing, and would be very thankfull for any advice.
For me the g++ main.cpp -o run.exe -lopengl32 seems to work just fine, so you most likely wont need -Wl,--enable-stdcall-fixup to compile it.
When I try compiling the file
#include "SDL2\SDL.h"
int main( int argc, char* argv[] )
{
//Start SDL
SDL_Init( SDL_INIT_EVERYTHING );
//Quit SDL
SDL_Quit();
return 0;
}
--an example from the SDL wiki--on the command line with
g++ -o SDL_Test.exe SDL_Test.cpp -lmingw32 -lSDLmain -lSDL
I get an error that says my computer cannot find -lSDLmain and -lSDL. Without the library things, it has trouble interpreting the functions.
I think the problem has something to do with the -l things, but I have no idea what they do....
My computer is 64-bit, if that makes a difference. I copied the x84_64-mingw32 bin, include, and lib into the C:\MinGW versions.
I would mostly just like an explicite solution to my problem, but if you could try explaining the -l things and other - things, that would be awesome.
-::- Answered by greatwolf in chat: turns out I was using 32-bit MinGW with 64-bit SDL files; I just needed to replace the 64-bit files with the 32-bit versions. Also, I had to direct the compiler to my SDL2.dll file. End compile command was g++ -o SDL_Test.exe SDL_Test.cpp -LC:\MinGW\lib -lmingw32 -lSDL2main C:\MinGW\bin\SDL2.dll.
You've got to make sure that you specify the appropriate search path for libraries using the -L compiler flag. Otherwise it won't know where to look for linking.
I've been learning SDL for a little time, and now I've decided to try out SDL2, mainly to try its hardware acceleration. But the problem is, I can't compile it at all, while the same code compiled correctly with SDL1.2.
The sample code is:
#include "SDL/SDL.h"
int main( int argc, char *args[] )
{
SDL_Init(SDL_INIT_EVERYTHING);
SDL_Quit();
return 0;
}
With the original linker settings: -lmingw32 -lSDLmain -lSDL
everything compiles.
But as soon as I change #include "SDL/SDL.h" to #include "SDL2/SDL.h"
and change linker settings to
-lmingw32 -lSDL2main -lSDL2
I get the errors:
obj\Debug\main.o||In function `SDL_main':|
main.cpp|5|undefined reference to `SDL_Init'|
main.cpp|8|undefined reference to `SDL_Quit'|
libmingw32.a(main.o):main.c:(.text.startup+0xa7)||undefined reference to `WinMain#16'|
I've got SDL1.2 installed in C:/SDL-1.2.15 and SDL2 installed in C:/SDL2
In search directories, I added both SDL1.2 and SDL2 Include and Lib folders.
I'm not sure if this will work, but if you are using the "x86_64-w64-mingw32" folder, try using the other one (the one with i686) this helped me. I was having the EXACT same problem as you, and using literally, to the line, the same test code as you. I hope this helps.
What flags do I need to add to g++ in order to compile code using allegro 5? I tried
g++ allegro5test.cpp -o allegro5test `allegro-config --libs`
but that is not working. I'm using ubuntu 11.04. I installed allegro 5 using the instructions at http://wiki.allegro.cc/index.php?title=Install_Allegro5_From_SVN/Linux/Debian
I tried:
g++ allegro5test.cpp -o allegro5test `allegro-config --cflags --libs`
And it also gives a bunch of undefined errors, like: undefined reference to `al_install_system'
allegro-config --cflags --libs outputs:
-I/usr/local/include
-L/usr/local/lib -lalleg
So you successfully installed allegro5 on your system from the SVN. One thing you should know is that this build doesn't come with allegro-config. If you have it on your system it means you have previously installed allegro4.
allegro5 brings many changes, including different initialization procedures, library and function names.
Here's a hello world application for new version:
#include <stdio.h>
#include <allegro5/allegro.h>
int main(int argc, char **argv)
{
ALLEGRO_DISPLAY *display = NULL;
if(!al_init()) {
fprintf(stderr, "failed to initialize allegro!\n");
return -1;
}
display = al_create_display(640, 480);
if(!display) {
fprintf(stderr, "failed to create display!\n");
return -1;
}
al_clear_to_color(al_map_rgb(0,0,0));
al_flip_display();
al_rest(10.0);
al_destroy_display(display);
return 0;
}
Notice how the command to compile this application refers to another include directory and library names, which are different from the previous version of allegro:
g++ hello.cpp -o hello -I/usr/include/allegro5 -L/usr/lib -lallegro
Allegro 5 uses pkg-config.
pkg-config --libs allegro-5.0 allegro_image-5.0
And so on for each library you are using.