I tryies to init OpenGL on windows without GLFW ... her some relevant code:
#include <windows.h>
//...
if(!(g_hDC = GetDC(hWnd)))
return false;
if(!(iPixelFormat = ChoosePixelFormat(g_hDC, &pfdPixelFormat)))
return false;
if(!SetPixelFormat(g_hDC, iPixelFormat, &pfdPixelFormat))
return false;
if(!(g_hRC = wglCreateContext(g_hDC)))
return false;
if(!wglMakeCurrent(g_hDC, g_hRC))
return false;
//...
when I compile with mingw32-g++ -Wall -O2 -Wl,--subsystem,windows -lopengl32 -mwindows Init.c I get following errors:
Temp\cclcIFFB.o:init.c:(.text+0x281): undefined reference to `_wglCreateContext#4'
Temp\cclcIFFB.o:init.c:(.text+0x2a0): undefined reference to `_wglMakeCurrent#8'
collect2.exe: error: ld returned 1 exit status
Why this linker error acours?
Try putting your Init.c before the -lopengl32:
mingw32-g++ -Wall -O2 Init.c -Wl,--subsystem,windows -lopengl32 -mwindows
gcc can be picky about argument positioning.
You must add the OpenGL linker definition library opengl32.lib to the list of to be linked libraries.
Related
I am trying to use functions in dlcfn.h, to print custom trace from my C application.
I do link with -ldl, yet the linker complains that it cannot find dladdr().
What am I missing?
Here is an example, inst.c:
#define _GNU_SOURCE
#include <dlfcn.h>
#include <stdio.h>
__attribute__((no_instrument_function))
void __cyg_profile_func_enter (void *this_fn, void *call_site) {
printf("%p\n", this_fn);
Dl_info info;
if (dladdr(this_fn, &info)) {
printf("%p [%s] %s\n",
this_fn,
info.dli_fname ? info.dli_fname : "?",
info.dli_sname ? info.dli_sname : "?");
}
}
__attribute__((no_instrument_function))
void __cyg_profile_func_exit (void *this_fn, void *call_site) {
}
void my_function_b(void)
{
printf("b!\n");
}
void my_function_a(void)
{
printf("a!\n");
my_function_b();
}
int main(void)
{
my_function_a();
my_function_b();
return 0;
}
And a Makefile:
CFLAGS += -O0 -g -finstrument-functions -rdynamic -ldl
inst: inst.c
gcc $(CFLAGS) $^ -o $#
The result:
$ make
gcc -O0 -g -finstrument-functions -ldl inst.c -o inst
/usr/bin/ld: /tmp/ccKL1sh2.o: in function `__cyg_profile_func_enter':
/home/gauthier/tmp/inst/inst.c:12: undefined reference to `dladdr'
collect2: error: ld returned 1 exit status
make: *** [Makefile:4: inst] Error 1
You should put libraries after source or object files which import their functions, otherwise linker will optimize them out:
gcc -O0 -g -finstrument-functions inst.c -ldl -o inst
I am trying to link guile to an Rcpp file. It seems like things compile but there is an error when loading:
sourceCpp("test_2.cpp", rebuild = TRUE, showOutput = TRUE)
/usr/lib/R/bin/R CMD SHLIB --preclean -o 'sourceCpp_2.so' 'test_2.cpp'
g++-10 -I"/usr/share/R/include" -DNDEBUG -I"/home/matias/R/x86_64-pc-linux-gnu-library/4.0/Rcpp/include" -I"/home/matias/Documentos/Program/R/guile" -fpic -O3 -march=native -mtune=native -fPIC -pthread -I"/usr/include/guile/3.0" -c test_2.cpp -o test_2.o
g++-10 -shared -L/usr/lib/R/lib -lm -ldl -lgmpxx -lgmp -lmpfr -lmpc -lguile-3.0 -lgc -o sourceCpp_2.so test_2.o -L/usr/lib/R/lib -lR
Error in dyn.load("/tmp/Rtmpm2flY8/sourceCpp-x86_64-pc-linux-gnu-1.0.5/sourcecpp_29e2d33505085/sourceCpp_2.so") :
unable to load shared object '/tmp/Rtmpm2flY8/sourceCpp-x86_64-pc-linux-gnu-1.0.5/sourcecpp_29e2d33505085/sourceCpp_2.so':
/tmp/Rtmpm2flY8/sourceCpp-x86_64-pc-linux-gnu-1.0.5/sourcecpp_29e2d33505085/sourceCpp_2.so: undefined symbol: scm_init_guile
The linking works fine if I remove the Rcpp header and build directly with g++ instead.
My Makevars look like this:
CXX = g++-10
CXXFLAGS = -O3 -march=native -mtune=native -fPIC -pthread -I"/usr/include/guile/3.0"
CXXSTD = -std=c++11
LDFLAGS = -lm -ldl -lgmpxx -lgmp -lmpfr -lmpc -lguile-3.0 -lgc
The .cpp file:
#include <Rcpp.h>
#include <stdio.h>
#include <libguile.h>
using namespace Rcpp;
// [[Rcpp::export]]
int test_guile() {
SCM func, func2;
scm_init_guile();
scm_c_primitive_load("script.scm");
func = scm_variable_ref(scm_c_lookup("simple-func"));
func2 = scm_variable_ref(scm_c_lookup("quick-test"));
scm_call_0(func);
scm_call_0(func2);
return 0;
}
You are so, so close. You essentially solved this. I just took your file, made a small modification of making the script an argument and (as you didn't post script.scm) commented out the content-specific stuff. We still load it though:
#include <Rcpp.h>
#include <stdio.h>
#include <libguile.h>
using namespace Rcpp;
// [[Rcpp::export]]
int test_guile(std::string file) {
SCM func, func2;
scm_init_guile();
scm_c_primitive_load(file.c_str());
//func = scm_variable_ref(scm_c_lookup("simple-func"));
//func2 = scm_variable_ref(scm_c_lookup("quick-test"));
//scm_call_0(func);
//scm_call_0(func2);
return 0;
}
Similarly I just added a src/Makevars to the Rcpp.package.skeleton() created file. This is not good enough to ship as you need some minimal configure or alike logic to get these values from guile-config-3.0 or alike. But it passes the litmus test. C++11 is the default already under R 4.0.*, and the compiler is recent on my box anyway so we just have this (after removing a few GNU GMP and related parts we do not need):
PKG_CXXFLAGS = -I"/usr/include/guile/3.0"
PKG_LIBS = -lguile-3.0 -lgc
This now builds, installs, and runs just fine:
> file <- system.file("guile", "script.scm", package="RcppGuile")
> RcppGuile::test_guile(file)
[1] 0
>
For reference, I committed and pushed the entire example package here. If you provide a pointer to script.scm we can add that too.
Edit: A few seconds of googling leads to the script.scm you may have used so now we have a fully working example with a working embedded Guile interpreter:
> library(RcppGuile)
> test_guile(system.file("guile", "script.scm", package="RcppGuile"))
Script called, now I can change this
Adding another function, can modify without recompilation
Called this, without recompiling the C code
[1] 0
>
This seems a simple but somehow the compile sends this error message which I'm not able understand thus correct my code.
This is a simplified version of what I did, just so it can appear the error for you:
Main.cpp
include "myfunction.h"
int main(){
std::vector<int> myVet = {1,4,3};
sequence(1,2,1,myVet);
}
myfunction.h
#include <vector>
/*funtion creates a sequence*/
void sequence(int start, int end,
int step, std::vector<int> skip);
myfunction.cpp
#include "myfunction.h"
void sequence(int start, int end,
int step, std::vector<int> skip){
auto x = 0;
};
This gives me an error message which says
In function 'main':
/home/machina/Documents/Grafos&Redes/Implementação/main.cpp:18: undefined reference to 'sequence(int, int, int, std::vector <int, std::allocator<int> >)'
collect2: error: ld returned 1 exit status
Could you please explain me why it appears?
This is the following command which I've been using for compiling
g++ -std=c++11 -g -Wall -Wextra -Werror main.cpp -o main.out
You are only passing main.cpp to g++.
g++ needs to know about myfunction.cpp where your function is defined so as to compile and link it to your program.
The command to use should be:
g++ -std=c++11 -g -Wall -Wextra -Werror main.cpp myfunction.cpp -o main.out
std::defaultfloat doesn't seem to be defined in GCC, despite being in the standard (I think it's §27.5.6.4). I've isolated it to this simple program:
// test.cpp
#include <iostream>
int main()
{
std::cout << std::defaultfloat << 1.3;
return 0;
}
This compiles in VC++11. I tried compiling this with g++ 4.7.2 and g++ 4.9.0 using both of these commands:
g++ test.cpp
g++ test.cpp -std=c++11
I also tried an online compile on GCC 4.8.1 here, always with the same result:
user#office-debian:~/Documents/test$ g++ test.cpp -std=c++11
test.cpp: In function ‘int main()’:
test.cpp:5:15: error: ‘defaultfloat’ is not a member of ‘std’
std::cout << std::defaultfloat << 1.3;
Why am I getting this error?
GCC libstdc++ just doesn't support these C++11 manipulators in any of
the versions you've compiled against. A patch was submitted exactly one month ago
These are my C codes simply print “Hello" Message. And I want to make mylib.c as shared library.
[mylib.c]
#include <stdio.h>
int mylib();
int main(){
mylib();
return 0;
}
int mylib(){
printf("### Hello I am mylib #####\n");
return 0;
}
[drive.c]
#include <stdio.h>
int mylib();
int main(){
mylib();
return 0;
}
At the firest I compiled mylib.c with folowing command line to make mylib.o
gcc –fPIC –g –c –Wall mylib.c
Then tried to make it shared librarly like this
gcc -shared -Wl,-soname,libmylib.so.1 -o /opt/lib/libmylib.so.1.0.1 mylib.o -lc
And I did ldconfig to update /etc/ld.so.cache
Finaly I compiled drive.c link with mylib but linker showed error
gcc -g -Wall -Wextra -pedantic -I./ -L./ -o drive drive.c –lmylib
/usr/bin/ld: cannot find –lmylib
Dose someone tell me how can I compile it?
In my way, you have to follow some ways to use shared library in C.
At first I have created a header file named "shared_library.h", in this file I have introduced a function named "method" as a function of this library.
The code is following:
/*-------This is starting of shared_library.h file-----------*/
void method();
/*-------------This is ending of shared_library.h file--------*/
Then I have defined the method in another file named "shared_library.c". The definition as in code is:
/*-------------This is starting of shared_library.c file---------*/
#include "shared_library.h"
void method()
{
printf("Method is called");
}
/*-------------This is ending of shared_library.c file---------*/
And finally, the header "shared_library.h" is ready to use. I use the library in my main C file named "main.c". The contents of "main.c" are as follows:
/*-------------This is starting of main.c file----------------*/
#include <stdio.h>
#include "shared_library.h"
int main()
{
method();
return 0;
}
/*-------------This is ending of main.c file----------------\*/
I found this article ld cannot find an existing library.
It works if I change to gcc -g -Wall -Wextra -pedantic -I./ -L/opt/lib -o drive drive.c –l:libmylib.so.1