I have a simple test program for OpenCV:
#include "opencv2/opencv.hpp"
#include "opencv2/core/core.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgcodecs/imgcodecs.hpp"
#include <iostream>
int main(int argc, char **argv){
std::cout << "HELLO" << std::endl;
cv::Mat im=cv::imread((argc==2)? argv[1]: "testing.jpg",cv::IMREAD_COLOR);
if (im.empty()){
std::cout << "Cannot open image." << std::endl;
} else {
cv::namedWindow("DisplayWindow",cv::WINDOW_AUTOSIZE);
cv::imshow("DisplayWindow",im);
cv::waitKey(0);
}
return 0;
}
However, when run the program does nothing. Hello is not printed to the console, and it does not output an error.
./main
#Nothing.......
It is worth noting that the program terminates, but not in the proper way. (The return value is non-zero) I do not think that this is a linking error, as those would actually output an error.
Any ideas on what is happening and/or how to fix it? I am using a Windows computer if that changes anything.
Turns out the windows cmd prompt actually has some use. (VERY surprising, I gave up on it a long time ago)
I ran the test program from the windows cmd line and it said the following libraries were missing.
libstdc++-6.dll
libgcc_s_dw2-1.dll
libwinpthread-1.dll
To fix the standard C++ and C libraries I just statically linked them using the below command. (This is apparently a common practice on Windows due to issues with version control):
g++ -static-libgcc -static-libstdc++ ...rest of compile/link cmd...
To fix the winpthread dll I just copied the dll to the bin folder of my program and everything worked!
Related
I have a program that is written in C & C++ and I'm rewriting some parts to improve it. This program has to work with files, but I am not able to check if a file exists on Windows with a cross-compiled exe.
To check if my code was the problem, I have created this simple example:
#include <fstream>
#include <iostream>
int main(){
std::fstream in_file("test.noexists", std::ios::in|std::ios::binary);
if (in_file) {
std::cout << "File exists" << std::endl;
}
else {
std::cout << "File doesn't exists" << std::endl;
}
}
Compiling this code using "x86_64-w64-mingw32-g++", version 8.3-win32 on Debian 10, I'm unable to check if a file exists because it always returns "true". To verify it I have compiled the same program on Linux using g++, and on Windows using mingw64, and both were working so looks like a problem building the project on Debian 10 mingw32.
I don't know if my problem is a bug on Debian version or I am doing something wrong. Anyone knows anything about it?
The only difference I have seen between both, is the version (8.1 on Windows vs 8.3 on Debian), and of course the SO.
Thanks!.
EDIT:
I have upgraded to Debian 11 which has the x86_64-w64-mingw32-g++ v10 and same behavior. I forgot to say that I am using Debian 11 on WSL, not a real Debian distribution. I don't think it matters.
EDIT2:
I have already seen the suggested thread, but the problem is that I want to use streams to manage the files and the only option in that thread also fails. Using any of the other three ways will be like a hack that will not help too much. I think that is not the best way to check the file presence with another example, and then reopen the file later to work with it.
Is supposed that the fstream class have boolean conversion as I have read in several threads and that is why I'm using this example. The Linux version works perfectly, so the function is working as expected. The problem is the Windows version compiled in Linux (cross compiled EXE).
I have tested in_file.good(), in_file.is_open(), in_file.bad(), just in_file... all of them returns like the file was open correctly. Also I have tried ifstream, but same behaviour.
Rest a bit always helps... I have found a workaround to my problem just reading 0 bytes.
#include <fstream>
#include <iostream>
int main(){
std::fstream in_file("test.noexists", std::ios::in|std::ios::binary);
char dummy;
if (in_file.read(&dummy, 0)) {
std::cout << "File exists " << in_file.tellg() << std::endl;
}
else {
std::cout << "File doesn't exists" << std::endl;
}
}
With this, even the cross compiled EXE works without problems.
I still thinking why only fails with the cross compiled EXE, but I was not able to find any info about it and how to fix it. At least this solution is working.
Best regards.
I'm trying to run a helloworld program which uses boost filesystem.
I'm on Windows with MinGW 8.1 and boost 1.70.
The problem is that, although everything compiles, the program doesn't run. I mean, it runs but doesn't print anything, which means the main function is not even executed:
#include <boost/filesystem.hpp>
#include <iostream>
using namespace std;
using namespace std::string_literals;
namespace fs = boost::filesystem;
int main()
{
cout << "Hello Boost!" << endl;
fs::path abHome{"C:/Users/Me"s};
fs::path jsonFile = abHome / "jsonFile.json"s;
if (!fs::exists(jsonFile)) {
cout << "Creating json file from scratch." << endl;
}
}
"Hello Boost" isn't ever printed to the console.
I've compiled with both CMake and g++ from command line to try to better understand what's going on:
g++ main.cpp -o main -L"C:/Code/boost_1_70_0/stage/lib" -lboost_filesystem-mgw81-mt-x64-1_70 -lboost_system-mgw81-mt-x64-1_70 -I"C:/Code/boost_1_70_0"
I've compiled boost for MinGW by following the guide and everything went well, in the output folder I see many different versions of each library based on the default targets (I haven't really picked them, just went with the defaults).
How can I debug the launch of main.exe to see what's causing the crash? It's been many years since I wrote C++ so I need help to get back on track! :)
The problem was, as #kenba pointed out, that the dynamic linking of the boost dlls was failing.
I erroneously thought I had linked the static version of the boost libraries.
To actually achieve that I should have used this command:
g++ main.cpp -o main -L"C:/Code/boost_1_70_0/stage/lib" -l:"libboost_filesystem-mgw81-mt-x64-1_70.a" -l:"libboost_system-mgw81-mt-x64-1_70.a" -I"C:/Code/boost_1_70_0"
instead of the one I posted in the OP.
I installed Codeblocks on my Windows 10 computer. To check that everything works fine, I first compiled the simple C program
#include <stdio.h>
#include <stdlib.h>
int main()
{
printf("Hello world!\n");
return 0;
}
That works without problem but when I try the C++ equivalent:
#include <iostream>
using namespace std;
int main()
{
cout << "Hello World!" << endl;
return(0);
}
Then the "command prompt" window opens but no output is shown. I can see in taskmanager that the program is running but as said without any visible output. I also tried running the program directly from the command line but with the same effect. Anyone any ideas?
I found the issue. There was still an older version of MinGW installed in a different folder. I deleted all instances of MinGW, and codeblocks as well. Adter I reinstalled codeblocks everything worked as it should.
This Guy solved similar problem with Codeblocks.
Remove the following Global compiler setting:
-Wl,-subsystem,windows
I have 3 computers, two of which use Windows 8. Using the latest version of MinGW's g++ (4.8.1-4) my hello world program freezes whenever I compile and run on the Windows 8 computers but not in Windows 7.
#include <iostream>
int main()
{
std::cout << "Hello, World!" <<std::endl;
return 0;
}
This compiles just fine in g++ but running a.exe will display "Hello, World!" then a window will pop up and say "a.exe has stopped working, Windows can check online for a solution to the program...." etc.
Has anybody seen this problem.
Also, I tried "std::cout << "Hello, World!\n" << std::flush;" and this has the same problem. It seems that every function that flushes the buffer causes a crash.
Following Eric's advice, I recompiled the program and ran it in gdb and got the following output:
Program received signal SIGILL, Illegal instruction.
0x00405065 in _Jv_RegisterClasses ()
In the second instance, the '\n' should cause an output flush in any case, although in Windows I believe console output is immediate (or perhaps automatic after a short timeout) in any case without an explicit flush.
I suggest the following experiments:
1) See if it is specific to the C++ library by using the C library (in MinGW Microsoft's C runtime is used rather than glibc):
#include <stdio.h>
int main()
{
printf( "Hello, World!\n" ) ;
return 0;
}
2) Eliminate the exit code by:
int main()
{
return 0;
}
3) No newline at all:
#include <iostream>
int main()
{
std::cout << "Hello, World! ;
return 0;
}
4) Try different compiler options such as optimisation levels, or -fno-builtin for example, or as suggested here: -static-libgcc -static-libstdc++ (although I doubt ``-static-libgcc` will itself have any effect since MinGW uses Microsoft's C runtime DLL and the static library is only available with Microsoft's tools).
I had the same issue and found after a long painful search that I had multiple versions of the mingw provided libstdc++-6.dll on my computer. One was part of the mingw installation the others were part of other installation packages (gnuplot and GIMP). As I had gnuplot in my PATH the compiled mingw exe it would use an older, incompatible version of this dll and crash with the described symptoms. I can, therefore, confirm Dietmar Kühl's suspicion. As suggested above linking the library statically obviously helps in this case as the library functions are included in the exe at compile time.
I have installed the newest MinGW suite. My project still compiles without any error but the produced executable is not working. Starting it results in the well known windows xp error message. Paradoxically source code like
#include <stdio.h>
int main()
{
printf("test\n");
return 0;
}
produces a working executable while
#include <iostream>
int main()
{
std::cout << "test\n" << std::endl;
return 0;
}
compiles fine but the executable is broken as described above.
Before i made the update everything worked. So what goes wrong here?
Do you have the libstdc++-*.dll in the path? It may be shared in newer MinGW versions, and std::cout uses it.
A tool like Process Monitor will probably tell you what is actually going wrong in more detail, and possibly even tell you what you need to fix to make it work.