#include <opencv2/opencv.hpp>
int main(int argc, char *argv[])
{
return 0;
}
With a simple program, such as that #including OpenCV as above, I would have expected to compile on Ubuntu using $CXX main.cpp, but on Ubuntu 21.10 I get a "file not found" error until I provide the header path via $CXX -I /usr/include/opencv4/ hello.cpp.
Is this a bug, or is there a package I am missing? on Ubuntu 21.10 to avoid explicitly specifying the include path?
Related
I am using MacOS 10.15. Since the clang shipped with MacOS does not include clang-format. I installed another pre-built clang binary from here. I have added the binary file path to my PATH variable.
export PATH="$HOME/tools/clang+llvm-10.0.0-x86_64-apple-darwin/bin:$PATH"
I tried to compile a simple program:
#include <iostream>
int main(int argc, char *argv[]) {
std::cout << "Hello world!\n";
return 0;
}
using the following command:
clang++ hello.cpp -o hello
I got the following error:
In file included from hello.cpp:1:
In file included from /Users/jdhao/tools/clang+llvm-10.0.0-x86_64-apple-darwin/bin/../include/c++/v1/iostream:37:
In file included from /Users/jdhao/tools/clang+llvm-10.0.0-x86_64-apple-darwin/bin/../include/c++/v1/ios:214:
In file included from /Users/jdhao/tools/clang+llvm-10.0.0-x86_64-apple-darwin/bin/../include/c++/v1/iosfwd:95:
/Users/jdhao/tools/clang+llvm-10.0.0-x86_64-apple-darwin/bin/../include/c++/v1/wchar.h:118:15: fatal error: 'wchar.h' file not found
#include_next <wchar.h>
^~~~~~~~~
1 error generated.
I found that wchar.h bundled with this pre-built package is in the following directory:
/Users/jdhao/tools/clang+llvm-10.0.0-x86_64-apple-darwin/include/c++/v1/
So I added the -I flag:
clang++ -I /Users/jdhao/tools/clang+llvm-10.0.0-x86_64-apple-darwin/include/c++/v1 hello.cpp -o hello
The error still persists.
If I use clang++ shipped with MacOS, I have no problem compiling the source code:
# the following works without any error
/usr/bin/clang++ hello.cpp -o hello
I have seen post here, here, and here, but the solutions do not apply.
You got clang-format improperly. Reset the system to the state before you installed another pre-built clang binary. Then use Homebrew to install clang-format
brew install clang-format
clang+llvm-10.0.0-x86_64-apple-darwin is not suitable to your Mac. It depends on system frameworks that are not available, so you get the error finding wchar.h in a system framework. When you install clang+llvm-10.0.0-x86_64-apple-darwin you ignore framework dependencies. Homebrew will care about dependencies.
I'm trying to pass the arguments from command line using command line parser library, in C in we can use the getopt() function but I am writing in C++ so I have to use cxxopts parser library, which on execution gives a fatal error that there is no such kind of library, I want a way to use cxxopts
i tried using cxxopts as #include<cxxopts.hpp> along with #include<iostream>
#include<iostream>
#include<cxxopts.hpp>
main(int argc, char *argv[])
{
int i;
for(i=0;i<argc;i++)
cout<<argv[i];
}
prob.cpp:2:22: fatal error: cxxopts.hpp: No such file or directory
#include
^
compilation terminated
I am using Arch Linux. According to the INSTALL, I download the newest release from here, move the cxxopts.hpp from the include to /usr/include/, then compile the example.cpp with clang++ example.cpp and run it:
$ ./a.out -a
Saw option ‘a’ 1 times
Arguments remain = 1
Saw 1 arguments
It works.
In the example.hpp, it has:#include "cxxopts.hpp"
I am trying to get an OpenGL program working on both linux and windows.
Here's my code [file=main.cc]:
#include <iostream>
#include "GL/glew.h"
using namespace std;
int main(int argc, char *argv[]){
cout << "Hello World\n";
return 0;
}
Simple enough. I'm on Linux and using
g++ main.cc -lGL -lGLEW -lSDL2
to compile my program. It works perfectly fine and if I run ./a.out I get a Hello World on my screen.
Then I try to compile it on Linux for Windows using the command
x86_64-w64-mingw32-g++ main.cc -lGL -LGLEW -LSDL2
Then however i get the error:
main.cc:3:21: fatal error: GL/glew.h: No such file or directory
#include "GL/glew.h"
^
compilation terminated.
I've already tried adding the -I/inclulde/path option with paths like /usr/include /usr/include/GL usr/include and the like, yet nothing wants to compile.
The Libraries that I'm using (or planning to) were installed using
#apt install libgl-dev libglew-dev libsdl2-dev
Any help would be very much appreciated (although I feel this is an incredibly easy fix that I'm just too stupid to figure out on my own)
I tried to compile a basic OpenGL program, simply just a blank window.
I'm using CodeLite with the g++ compiler on Linux Mint 18.1 (Ubuntu 16.04 LTS).
The code so far is:
#include <stdio.h>
#include <GL/glew.h>
#include <GL/freeglut.h>
int main(int argc, char **argv)
{
glutInit(&argc, argv);
printf("hello world\n");
return 0;
}
At first my compiler (G++ in CodeLite) gave the error
/home/USER/Projects/CodeLite/Graphical/main.cpp:7: undefined reference to `glutInit'
I downloaded all the up to date GLEW and GLUT includes from their respective websites and unpacked them to /usr/include/GL, I edited the project settings linker like this.
Now it gives the error message:
/usr/bin/ld: cannot find -lglut
Makefile:4: recipe for target 'All' failed
What can I do to fix this?
You should install the libraries from the package manager instead: libglew-dev, freeglut3-dev, libgl1-mesa-dev and libglu1-mesa-dev. The includes and binary files will be placed in the appropriate location.
If the linker cannot find the .so files, locate them with dpkg -L freeglut3-dev and add this directory in the linker command line
g++ -L/path/to/libglut.so *.o -o programname
I'm trying to use the GLFW library, but am having difficulty with compiling a simple program. I went to the GLFW website and download the latest release, then using "How to build & install GLFW 3 and use it in a Linux project" I built and installed it.
Here's my code:
#include <GLFW/glfw3.h>
#include <iostream>
using std::cout;
using std::endl;
void GLFW_error(int error, const char* description)
{
fputs(description, stderr);
}
void run()
{
cout << "pooch" << endl;
}
int main()
{
glfwSetErrorCallback(GLFW_error);
if (!glfwInit()) exit(EXIT_FAILURE);
run();
glfwTerminate();
return 0;
}
Using the command line:
bulletbill22#ROBOTRON ~/Desktop $ g++ -std=c++11 -lglfw source.cpp
yields
source.cpp:function main: error: undefined reference to 'glfwSetErrorCallback'
glfwSetErrorCallback is taken from their tutorial for "Setting an error callback".
Inclusion of -glfw3 results in /usr/bin/ld: error: cannot find -lglfw3
Even though everything seemed to be installed correctly, I suspect the problem may lie somewhere with the installation of the GLFW library because I'm not used to CMake and don't entirely understand how it works. I'm frustrated because the answer must be simple, but I'm not sure which keywords are really relevant when googling the problem; mostly the results are people who were incorrectly compiling with CMake, which I'm not compiling with in this case.
It seems that the directories for the glfw3.h header and libglfw3.so (and/or libglfw3.a) library are not in the default path.
You can check with by adding the -v option to the g++ options. Locate the directory where the glfw3.h header is found - call this $GLFW_INCDIR - it typically ends with .../GLFW. Locate the directory where the library is found - call this $GLFW_LIBDIR. Try:
g++ -std=c++11 -I$GLFW_INCDIR source.cpp -o pooch -L$GLFW_LIBDIR -lglfw3
If all the library dependencies are satisfied, this hopefully results in a program called pooch.
One other thing: GLFW3 is a C library, and the callback function arguments are expected to be C functions. So your callback should have 'C' linkage, i.e.,
extern "C" void GLFW_error(int error, const char* description) ...
Also, if you're having trouble with cmake, you may have ccmake installed. Try ccmake . in the top-level directory of the GLFW3 package for 'interactive' configuration.