I am writing a code about the deadlocks and their detection, i use eclipse Juno C/C++ on Ubuntu 12.10, 64 bit.
The problem is when i use
sleep(1)
, i get this
sleep was not declared in this scope
when i build the project, i tried to include
include < unistd.h>
, but then all the pthread functions like
pthread_join
gives me errors like
undefined reference to pthread_join
, without #include < unistd.h> such error doesn't show up.
sample code:
#include <unistd.h>
#include <iostream>
#include <semaphore.h>
#include <queue>
#include <stdlib.h>
using namespace std;
pthread_mutex_t mutex;
sem_t sem; //used for writing in the console
.......
void cross(Batman b) {
// code to check traffic from the right, use counters, condition
sem_wait(&sem);
cout << "BAT " << b.num << " from " << b.direction << " crossing" << endl;
sem_post(&sem);
sleep(1);
}
........
p.s. i followed these instructions to get pthreads working in other project and i did the same for this project
http://blog.asteriosk.gr/2009/02/15/adding-pthread-to-eclipse-for-using-posix-threads/
p.s. i am working on this project with a friend and i used the same code he uses and still get those errors, while he doesn't
when you #include < unistd.h>, you fixed sleep function look up issue, now you have pthread library issue.
Next you need to #include <pthread.h> and link your application with pthread library
It sounds like you have two different errors,
first sleep() is undefined because you forgot to include unistd.h. I'd also include pthread.h but it sounds like it might get pulled in by one of the headers you include.
Secondly it sounds like you have a linker error add, you can either compile with -pthread or add -lpthread to the linker. The reason it doesn't show up is because linking can only be done once the files have been compiled and the first error is blocking this. I'd bet that ld doesn't like -pthread for some reason (have you installed libpthread-dev?). You can try changing -pthread to -lpthread.
Related
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 wanted to practice with standard C++ threads instead of UNIX ones, but soon encountered a problem, whenever I write std::thread CLion underlines it with red and says Can't resolve namespace member 'thread'. I checked my CMake file it's set for C++11. I reinstalled the latest version of MinGW (6.3.0) and ticked a box with G++ compiler. I have been told by my friend that he uses Cygwin and everything works. But is it still possible to make it work with MinGW?
#include <iostream>
#include <thread>
#define BUFFER_SIZE 3
#define PROD_NUM 3
#define CONS_NUM 2
void produce(){
//production
}
void consume(){
//consumption
}
int main() {
std::cout << "Hello, World!" << std::endl;
int i,j;
std::thread producer(produce);
std::thread consumer (consume);
return 0;
}
The code itself has literally nothing
EDIT
in thread library there is
#pragma GCC system_header
#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#else
#include <chrono>
#include <functional>
#include <memory>
#include <cerrno>
#include <bits/functexcept.h>
#include <bits/functional_hash.h>
#include <bits/gthr.h>
#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* #defgroup threads Threads
* #ingroup concurrency
*
* Classes for thread support.
* #{
*/
/// thread
class thread
{
public:
// Abstract base class for types that wrap arbitrary functors to be
// invoked in the new thread of execution.
struct _State
{
virtual ~_State();
virtual void _M_run() = 0;
};
can you make sure if the library is available in the CLion toolchain? For example Cygwin does have the include.
CLion shows things red when it can't link codes with the library.
It is possibly a host environment variable error. Make sure your CMakeLists.txt is working and your environment variables, standard library linkage is correct as well as your compiler setup.
Compiler version and and standard libraries compatible. (e.g. you are using a cross-compiler (RasPi, Android) but environment vars shows host library etc. will make it fail)
Check this relevant post, it may help.
C++11 std::threads vs posix threads
Ok, so I finally solved the problem. I installed Cygwin and in CLion Settings I manually linked C/C++ compilers (for some reason CLion was unable to auto-detect them). Cleared all and re-indexed the project. Now it shows no errors and code compiles.
Regarding MinGW, I read on cplusplus.com some posts regarding the issue but they were about previous versions of MinGW and it was said that they finally fixed it, however I tell: No, they didn't. Here there is a nice repository and its README file suggests that thread of win32 rely on gthreads, however i found gthread file in my libraries everything seemed ok... so still need to investigate the issue. Write your ideas and experience here if you know more.
As for now solution is Cygwin, use it instead of MinGW.
P.S. Thanks #KillzoneKid for links
I'm using GMP and getting an illegal instruction that I have found to be caused by mpf_set_d. I'm programming in Netbeans with cygwin in c++.
Thanks in advance!
Edit:
I have a folder containing the following files:
.dep.inc, cyggcc_s-seh-1.dll, cyggmp-10.dll, cyggmpxx-4.dll, cygstdc++-6.dll, cygwin1.dll, my executable, gmp.h, gmpxx.h, libgmp.a, libgmp.la, libgmp.lai, libgmp.lai, libgmp.libcmd, libgmpxx.a, libgmpxx.la, libgmpxx.lai, main.cpp, main.o, main.o.d, Makefile, text file needed for program and folders needed for program.
I have tried many things, one of which was to add an executable to this folder that ran the following code:
#include <cstdlib>
#include <iostream>
#include <stdio.h>
#include "gmpxx.h"
#include <stdarg.h>
#include <string>
using namespace std;
int main()
{
mpf_t a;
mpf_init(a);
mpf_set_d(a,3.1415926535);
cout << "works" << endl;
}
Running this on my own computer with GMP installed gives me 'works' after which it closes, on another computer that does not have GMP installed it throws an error and closes. The error is an exception: status_illegal_instruction.
I can't give you my code but I can post snippets. Please tell me if more information is necessary!
Thanks again.
Edit 2:
The same counts for mpf_set_str as well as the c++ wrapper.
I've been trying to run some of the example code (BermudanSwaption) in Xcode but keep getting an EXC_BAD_ACCESS code=2.
But compiling and running the BermudanSwaption code in the terminal works correctly.
The following code throws the same error in Xcode.
#include <ql/quantlib.hpp>
#include <iostream>
using namespace QuantLib;
int main (){
Date date(18, March, 2014);
std::cout << date << std::endl;
}
And this runs correctly.
g++ -I/opt/local/include/ -I/opt/local/include/boost main.cpp -o main -L/opt/local/lib/ -lQuantLib
Are there some specific settings I need to tweak in Xcode in order for this to run?
I found that #including the individual libraries separately rather then including ql/quanlib to work. So in my example sub ql/quantlib.hpp with ql/time/date.hpp and everything runs fine.
Following the suggestion of Kaush, and a bit of trial and error, the following works for me in QuantLib 1.4, and means you don't have to add in every single individual library:
In <ql/experimental/models/all.hpp>, comment out these lines:
#include <ql/experimental/models/kahalesmilesection.hpp>
#include <ql/experimental/models/markovfunctional.hpp>
main.cpp
#include <iostream>
#include <string>
using namespace std;
void echo(string);
int main()
{
echo("hello");
cout << "Hello world!" << endl;
return 0;
}
print.cpp
#include <iostream>
#include <string>
void echo(string code){
cout << code;
}
After compiling the code in code blocks 12.11, it gives me that error:
undefined reference to `echo(std::string)
I use windows 7 x64.
I have added the directory; Project>build options > search directories and added the current working directory.
All the files are in one console project in code blocks
I believe you should read up a bit more on namespaces usage. You are missing std in print.cpp.
Generally, while starting to learn cpp or getting a grip of the language you should always try writing full names of the classes along with the namespaces. Eventually with practice and some oversights (like now) you will learn why you really need them. In a nutshell namespaces are great:
When you are writing code over multiple files
Compartmentalize your code into separate blocks.
Also, using namespace std; should be used within cpp files mostly (otherwise headers get mangled up.
Anyways, try changing your code to this:
#include <iostream>
#include <string>
void echo(std::string code){
std::cout << code;
}
Then your results will look like this:
> g++ main.cpp print.cpp -o a.out
> ./a.out
helloHello world!
You should get more than that linker error, since you use string without any namespace in your print.cpp file. And if that source file doesn't compile it can't be linked with, and you will get the linker error you have.
Change to e.g.
void echo(std::string code) { ... }
And you do try to link with the object file created from print.cpp ?
I know this is old, but for anyone looking to solve this issue, the following may be a solution for you. If you have g++ follow c++ 11 under project->build options (check your options anyway) then you must check that box for all files you make in the project for the error to be cleared up. I had that annoying undefined reference thing too but now it is gone!
Try "Project/Properties/Build Targets tab". There you should find "Build target files" field. In that filed find "print.cpp" and click the checkbox (now the compiler will build print.cpp).
Some usefull information on Project management in CB
http://www.codeblocks.org/docs/main_codeblocks_en.html
When dealing with strings in C++ its best to sue std::string and your code seems to be wrong with a changes like using std::cout instead of plain cout another thing you need to be careful is linking your files especially files in different directories you need to tell code blocks were to find this print.cpp by going to build option and go for the search tab directory and point to where print.cpp is other wise the other approach is to just build a project which will have the main.cpp and and then add print.cpp class to current project I hope this will be of some help