Is there anyway to use openmp with dev c++. I have seen links on how to use in Visual Studio, but i am more comfortable with Dev C++ interface.
Adding /openmp in the linker command line doesnt work either.
I couldnt find the library to download too. Am i missing something.
I tried running this sample code:
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[])
{
#pragma omp parallel
{
printf("Hello, world.\n");
}
return 0;
}
From where I read it was mentioned Output on a computer with 2 Cores and 2 threads will be hello world printed twice. I have a core i7 but it was printed only once.
Tools > Compiler Options > Check the option "Add the following commands when compiler is called" > in the text area put "-fopenmp"
Compile and execute again :)
I do not know Dev C++, but to enable openmp you also need to add the flag -fopenmp to your compiler.
Additional to linking to omp.
With g++ it look like this
g++ yourProgram.cpp -o yourProgram -lgomp -fopenmp
-fopenmp will tell the compiler to generate parallel code. I hope this will help.
You have to include -fopenmp in
Project-> Project Option->Parameters - Link
and
Tools ->Compiler Options (General)
(check "add the following commands when calling the compiler"
and include -fopenmp in the textBox
I have also included #include <omp.h>
dev-c++ version 5.6.1
there is only the parallel region , the processor is informed that there is what parallelize , but as is parallelize the code they have to say via builders, probably what you want to use : #pragma omp sections
I guess you also have to include the header file #include < omp.h > separately
Related
It's just a piece of "hello world" C++ code.
#include <stdio.h>
int main(int argc, char* argv[])
{
printf("hello");
return 0;
}
I compiled the code with clang 3.9. The command is: clang -m32 hello.cpp -o hello.exe, and the target executable size is about 44kb. It didn't make any difference with "O3" option added to the command.
While I compiled it with visual studio 2010, the size of the target executable file is only 6kb for release version and 28kb for debug version.
Could anyone help to explain the difference between the two versions' binary.
Any help would be appreciated.
I use clang-cl that accepts the flag /MD instead of clang. Problem resolved. I still need to explore what's the difference between clang and clang-cl.
all.
Compiling simple stuff using the gcc toolchain for several years, today I ran against a curious phenomenon.
I installed Kubuntu 14.04 to a common desktop i686 machine with gcc 4.8.2 in it. But then, trying to build some well coded stuff pulled out from my local repository, I ran against tons of 'undefined reference to' messages. The code compiles, links und runs well under Ubuntu 11.04 / gcc 4.5.2.
I checked the linking process (by -Wl,--verbose to gcc), think it works. It finds all libraries I specify in the link command. An objdump -t myLib.so brings exactly the symbols I'd expect - but the linker doesn't see them.
Checking the pthread library also brings according symbols, except they are suffixed with some #GLIBC... stuff. Didn't check linker/loader tricks so far.
A sample like
#include <stdio.h>
#include <unistd.h>
#include <pthread.h>
static void *fooo (void *xxx) {
char *txt = (char*)xxx;
printf("My job is to print this :'%s'. Bye now!\n", txt);
return 0;
}
int main (int argc, char *argv[]) {
pthread_t thd;
pthread_create(&thd, NULL, fooo, "A POSIX thread");
sleep(1);
return 0;
}
runs very well on the old system just saying
gcc -l pthread fooo.c && ./a.out
but breaks at the linking step with 4.8.2.
Any idea would be very welcome.
.M
Thanks to sfrehse, JoachimPileborg et al!
Indeed, success depends on argument order. I knew this fact for static linking, but it is new in processing of shared objects with gcc.
Does someone know what the background of this improvement is? It breaks innumerable build processes, and I guess thousands of tomatoes are being made ready against gcc.gnu.org .....
.M
I'm really a Python developer exclusively, but I'm making my first foray into C programming now, and I'm having a lot of trouble getting started. I can't seem to get the hang of compilation and including libraries. At this point, I'm just identifying the libraries that I need and trying to compile them with a basic "hello, world" app just to make sure that I have my environment setup to do the actual programming.
This is a DBus backend application that will use GIO to connect to DBus.
#include <stdlib.h>
#include <gio/gio.h>
int
main (int argc, char *argv[])
{
printf("hello, world");
return 0;
}
Then, I try to compile:
~$ gcc main.c
main.c:2:21: fatal error: gio/gio.h: No such file or directory
#include <gio/gio.h>
I believe that I've installed the correct packages as indicated here, and gio.h exists at /usr/include/glib-2.0/gio/gio.h.
I found a command online to add a search directory to gcc, but that resulted in other errors:
~$ gcc -I /usr/include/glib-2.0/ main.c
In file included from /usr/include/glib-2.0/glib/galloca.h:34:0,
from /usr/include/glib-2.0/glib.h:32,
from /usr/include/glib-2.0/gobject/gbinding.h:30,
from /usr/include/glib-2.0/glib-object.h:25,
from /usr/include/glib-2.0/gio/gioenums.h:30,
from /usr/include/glib-2.0/gio/giotypes.h:30,
from /usr/include/glib-2.0/gio/gio.h:28,
from main.c:2:
/usr/include/glib-2.0/glib/gtypes.h:34:24: fatal error: glibconfig.h: No such file or directory
#include <glibconfig.h>
^
compilation terminated.
There has to be some relatively simple method for being able to set some options/variables (makefile?) to automatically include the necessary headers. I'm also going to use Eclipse-CDT or Anjuta as an IDE and would appreciate help to fix the import path (or whatever it's called in C).
Any help is greatly appreciated.
Use pkg-config (and make). See exactly this answer to a very similar question. See also this and that answers. Don't forget -Wall -g flags to gcc ..
You don't need an IDE to compile your code (the IDE will just run some gcc commands, so better know how to use them yourself).
For a week I've been struggling with compiling openCV programs. I've tried everything I could possibly find on the internet.
What I did is: I've downloaded OpenCV-2.3.1-win-superpack.exe and followed this official installation guide.
In the CMake (gui) my source was: D:\opencv and build destination was: C:\opencv.
I've also added C:\opencv\install\bin;C:\opencv\bin to my system's PATH variable.
What I want is to compile openCV programs on my Windows OS using MinGW's gcc/g++ compilers.
I've tried various gcc/g++ parameters that I've found on the internet and days playing with the -I and -L options the compiler can never find the openCV functions or structures.
What I am trying to compile:
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <cv.h>
#include <highgui.h>
int main(int argc, char *argv[])
{
// Nothing but create a window
cvNamedWindow("mainWin", CV_WINDOW_AUTOSIZE);
cvMoveWindow("mainWin", 100, 100);
cvWaitKey(0);
return 0;
}
Error:
Input:
gcc test.c -o test -I"C:\opencv\install\include" -I"C:\opencv\install\include\opencv" -L"C:\opencv\install\bin"
Output:
...\ccK4MfHv.o:test.c:(.text+0xa0b): undefined reference to `cvFree_'
Or with g++:
Input:
g++ test.c -o test -I"C:\opencv\install\include" -I"C:\opencv\install\include\opencv" -L"C:\opencv\install\bin"
Output:
...\ccXCTKa1.o:test.c:(.text+0x1e): undefined reference to `cvNamedWindow'
Side note: trying to compile in VS2005 I get the same error.
Thank you for your time!
In case someone else needs to solve this issue, here's how I got the posted OpenCV/HighGUI sample code to compile in Windows 7 x64 using MinGW, MSYS, and CMake:
build OpenCV from source using MinGW/MSYS/CMake. This is because I could not get the MinGW compiled version in the OpenCV-win-SuperPack to link properly in MinGW/MSYS/Windows 7 x64.
For full reference, here's how I compiled OpenCV:
make sure you have an up-to-date CMake (v2.6 or later) and MinGW (with GCC, G++, and MSYS options) installed
if you want the new Qt-based OpenCV HighGUI front-end, you will need to install Qt 4 (SDK).
download a OpenCV source/superpack version 2.2 or later (I used OpenCV-2.3.1-win-superpack.exe)
unzip the contents to [OPENCV_SOURCE_DIR] (I put it in C:/opencv, so there should be a file at C:/opencv/README for example)
create a [OPENCV_BUILD_DIR] directory elsewhere (I used C:/opencv/build/mingw)
use the CMake-GUI tool, specify the source directory as [OPENCV_SOURCE_DIR], the build directory as [OPENCV_BUILD_DIR], and click "Configure".
you may wish/need to go tweak the options (e.g. I ticked "Qt" and "Qt-OpenGL" entries, then clicked "Configure" again, then had to provide the path to the qmake executable)
once you have finished configuring OpenCV, click "Generate"
in a MSYS terminal, browse to [OPENCV_BUILD_DIR], and run "make" to build the code (this may take a while)
once the has been built properly, run "make install", which collects the built code/libraries/include dirs into [OPENCV_BUILD_DIR]/install folder (or a different folder if you changed the corresponding option when using the CMake-GUI tool)
add [OPENCV_BUILD_DIR]/install/bin folder to the PATH environmental variable. If you do not know how to do this, then I'd recommend using the Path Editor GUI tool.
if you end up using Qt, you will also need to put the bin folder of Qt SDK in the PATH environmental variable. This is the folder that includes qmake.exe.
put the following sample code into a file called test.c. I modified the includes slightly to make them compatible with OpenCV v2.2 and above.
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <opencv/cv.h>
#include <opencv/highgui.h>
int main(int argc, char *argv[])
{
// Nothing but create a window
cvNamedWindow("mainWin", CV_WINDOW_AUTOSIZE);
cvMoveWindow("mainWin", 100, 100);
cvWaitKey(0);
return 0;
}
in a MSYS terminal, browse to the folder where you put test.c, and run:
gcc -o test -I"[OPENCV_BUILD_DIR]/install/include" test.c \
-L"[OPENCV_BUILD_DIR]/install/lib" \
-lopencv_core[OPENCV_VERSION] \
-lopencv_imgproc[OPENCV_VERSION] \
-lopencv_highgui[OPENCV_VERSION]
So in my case:
gcc -o test -I"/c/opencv/build/mingw/install/include" test.c \
-L"/c/opencv/build/mingw/install/lib" \
-lopencv_core231
-lopencv_imgproc231
-lopencv_highgui231
Path Editor: http://www.redfernplace.com/software-projects/patheditor/
You have the directory, C:\opencv\install\bin, to locate libraries on the gcc/g++ command line, but I think you'll also need to specify the libraries to use as linker inputs as well. I'm not sure what libraries are part of the OpenCV distribution, but going by the example on the instruction page you linked to, one might be:
-lopencv_calib3d220.dll
You'll probably have to add one or more other ones (that follow the name pattern lib*.a in the C:\opencv\install\bin directory - or maybe some other lib directory that you should be passing in a -L option).
I wrote a c++ program using boost library in Xcode. Here is my code. It is very simple.
#include <iostream>
#include </usr/local/include/boost/math/special_functions/beta.hpp>
using namespace std;
using namespace boost::math;
int main (int argc, char * const argv[])
{
double a = 100.0;
double b = 100000.0;
double x = 0.3;
double result = beta(a, b, x);
cout << result << endl;
return 0;
}
But when I tried to build it in the Xcode, there popped up a lot of errors related to the library linking stuff. I noticed that the compiler that Xcode was using was "System Default: gcc 4.2". And all other options are gcc or LLVM gcc (I have no idea what this is).
I later tried to compile the file simply using terminal. Weird thing happened. If I compile it with g++, without any extra flags, the compilation completed successfully and the the program could be ran normally; but if I compile it with gcc, there are pages of errors.
So, to sum it up, while using g++, everything is OK; while using gcc, everything is not OK. Since the Xcode is using gcc, the program could not be compiled using Xcode.
(And I kind of need to use the Xcode because this is just a test program, I actually have a much bigger project to handle and I depend on the debugger of Xcode.)
So my question is, WHAT THE HELL is the difference between gcc and g++? Or how can I change the compiler of Xcode to g++?
gcc is a C compiler.
g++ is a C++ compiler.
You're trying to compile C++, ergo, you need to use a c++ compiler.
Googling "Using XCode for c++" brings up lots of results, but this one seemed fairly straightforward and had pictures:
https://www.cs.drexel.edu/~mcs171/Wi07/extras/xCode_Instructions/index.html
The gcc command compiles C files (although you can use -libstdc++) to link C++ files as well but I don't recommend it.
The g++ command works for C++ files which is why it worked in your case.
For XCode you have to change the compiler from GCC to G++ for it to successfully work.