I'm trying to compile a little test program with Open ALPR as described on https://github.com/openalpr/openalpr/wiki/Integrating-OpenALPR.
I've come up with something like:
#include <alpr.h>
#include <iostream>
int main (void)
{
alpr::Alpr openalpr("us", "/etc/openalpr/openalpr.conf");
std::cout << "Hello World!" << std::endl;
return 0;
}
but I am unable to get it to compile. I've tried:
g++ -Wall -l /usr/lib/libopenalpr.so test.cpp -o test but I get
/usr/bin/ld: cannot find -l/usr/lib/libopenalpr.so.
/usr/lib/libopenalpr.so does exist and links to libopenalpr.so.2, which also exists. What is the correct way to link to this library?
The answer can be found here:
unable to compile with library
Related
I am trying to build a static library using MinGW.
Everything was going fine until I tried to use the library and got an error saying that add_numbers is an undefined function.
Many other people have had this problem and sorted it out by moving their library to be linked after the source files were included, but that was how I had written my batch file anyway, so that was not of much help.
Here are my sources.
mylib.h
#ifndef MYLIB_H
#define MYLIB_H
int add_numbers(int a, int b, int c);
#endif
mylib.c
#include "mylib.h"
int add_numbers(int a, int b, int c)
{
return a+b+c;
}
I'm building my .a file with the following commands
gcc --std=c89 -c mylib.c -o mylib.o
ar rcs libmylib.a mylib.o
I've also tried with out specifying the standard.
There are no errors or warnings when running this command.
Next, my test program looks like this.
#include <stdio.h>
#include "mylib.h"
int main()
{
printf("The sum of 1, 2, and 3 is %d", add_numbers(1, 2, 3));
getchar();
return 0;
}
And lastly, we build the test with this command.
gcc mylibtest.c -L -lmylib -o test.exe
I've tried moving around those commands into many many different sequences, but always receiving the following error:
C:\Users\Aaron\AppData\Local\Temp\cc0ERpBi.o:mylibtest.c:(.text+0x26): undefined
reference to `add_numbers'
collect2.exe: error: ld returned 1 exit status
E:\my_first_static_library>
Any help would be very appreciated, I've read every tutorial I could find on the art of writing static libraries, as well as a good ten stackoverflow questions.
You are missing a dot after -L:
gcc mylibtest.c -L . -lmylib -o test.exe
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
Having trouble compiling the following C++ code on Windows 7:
#include <boost/asio.hpp>
#include <iostream>
void handler1(const boost::system::error_code &ec)
{
std::cout << "5 s." << std::endl;
}
void handler2(const boost::system::error_code &ec)
{
std::cout << "10 s." << std::endl;
}
int main()
{
boost::asio::io_service io_service;
boost::asio::deadline_timer timer1(io_service, boost::posix_time::seconds(5));
timer1.async_wait(handler1);
boost::asio::deadline_timer timer2(io_service, boost::posix_time::seconds(10));
timer2.async_wait(handler2);
io_service.run();
}
I have MinGW installed (gcc 4.8.1) in c:\mingw with my PATH set up correctly. I have downloaded boost and declared environment variable BOOST_ROOT to be the path where it resides. I have gone through the bootstrap and b2 procedure for boost. I now try and compile:
c:\path\to\sandbox> g++ -I%BOOST_ROOT% -o main main.cpp
Gives a bunch of error: '::UnregisterWaitEx' has not been declared errors
I then search a bit and see I may need to link boost_system. So:
c:\path\to\sandbox> g++ -I%BOOST_ROOT% -lboost_system -o main main.cpp
Same errors. Thought I'd try specify library path. Did a search for boost_system and found static libs (libboost_system-mgw48-mt-1_55.a) in %BOOST_ROOT%/stage/lib. So
c:\path\to\sandbox> g++ -I%BOOST_ROOT% -L%BOOST_ROOT%/stage/lib -lboost_system-mgw48-mt-1_55 -o main main.cpp
Same errors. So I search again and see others suggesting appending a -D-D_WIN32_WINNT=0x0601. So
c:\path\to\sandbox> g++ -I%BOOST_ROOT% -L%BOOST_ROOT%/stage/lib -lboost_system-mgw48-mt-1_55 -o main main.cpp -D_WIN32_WINNT=0x0601
And the inevitable errors:
c:\mingw\include\mswsock.h:125:20: error: 'WSAPOLLFD' was not declared in this scope
int WSAAPI WSAPoll(WSAPOLLFD, ULONG, INT);
^
c:\mingw\include\mswsock.h:125:36: error: expected primary-expression before ',' token
int WSAAPI WSAPoll(WSAPOLLFD, ULONG, INT);
^
c:\mingw\include\mswsock.h:125:41: error: expected primary-expression before ')' token
int WSAAPI WSAPoll(WSAPOLLFD, ULONG, INT);
^
c:\mingw\include\mswsock.h:125:41: error: expression list treated as compound expression in initializer [-fpermissive]
Where am I going wrong?
I went ahead and rebuilt Boost again with b2 toolset=gcc --build-type=complete. Same thing happened. Finally, after all that, it turned out all I needed was to put the linking at the end of the command:
C:\path\to\sandbox> g++ -D_WIN32_WINNT=0x0601 -I%BOOST_ROOT% -L%BOOST_ROOT%\stage\lib -o boosttest boosttest.cpp -lwsock32 -lws2_32 -lboost_system-mgw48-mt-d-1_55
C:\path\to\sandbox> boosttest.exe
5 s.
10 s.
The -D_WIN32_WINNT was still necessary and, for anyone who has skipped the other comments, I had to patch winsock.h as detailed http://sourceforge.net/p/mingw/bugs/1980/. And remember to put %BOOST_ROOT%\stage\lib in your PATH so Windows can find the dll at runtime.
Arduous
I want to have a .cuh file where I can declare kernel functions and host functions as well. The implementation of these functions will be made inside the .cu file. The implementation will include the use of the Thrust library.
In the main.cpp file I would like to use the implementation that is inside the .cu file. So let's say we have something like this:
myFunctions.cuh
#include <thrust/sort.h>
#include <thrust/device_vector.h>
#include <thrust/remove.h>
#include <thrust/host_vector.h>
#include <iostream>
__host__ void show();
myFunctions.cu
#include "myFunctions.cuh"
__host__ void show(){
std::cout<<"test"<<std::endl;
}
main.cpp
#include "myFunctions.cuh"
int main(void){
show();
return 0;
}
If I compile by doing this:
nvcc myFunctions.cu main.cpp -O3
And then run the executable by typing ./a.out
The test text will be printed.
However, if I decide to include -std=c++0x by using the following command:
nvcc myFunctions.cu main.cpp -O3 --compiler-options "-std=c++0x"
I get a lot of errors, some of which are the following:
/usr/include/c++/4.6/x86_64-linux-gnu/./bits/c++config.h(159): error: identifier "nullptr" is undefined
/usr/include/c++/4.6/x86_64-linux-gnu/./bits/c++config.h(159): error: expected a ";"
/usr/include/c++/4.6/bits/exception_ptr.h(93): error: incomplete type is not allowed
/usr/include/c++/4.6/bits/exception_ptr.h(93): error: expected a ";"
/usr/include/c++/4.6/bits/exception_ptr.h(112): error: expected a ")"
/usr/include/c++/4.6/bits/exception_ptr.h(114): error: expected a ">"
/usr/include/c++/4.6/bits/exception_ptr.h(114): error: identifier "__o" is undefined
What do these errors mean and how can I avoid them?
Thank you in advance
If you look at this specific answer, you'll see the user is compiling an empty dummy app with the same switch you are using and getting some of the exact same errors. If you restrict the usage of that switch to compiling .cpp files, you'll probably have better results:
myFunctions.h:
void show();
myFunctions.cu:
#include <thrust/sort.h>
#include <thrust/device_vector.h>
#include <thrust/remove.h>
#include <thrust/host_vector.h>
#include <thrust/sequence.h>
#include <iostream>
#include "myFunctions.h"
void show(){
thrust::device_vector<int> my_ints(10);
thrust::sequence(my_ints.begin(), my_ints.end());
std::cout<<"my_ints[9] = "<< my_ints[9] << std::endl;
}
main.cpp:
#include "myFunctions.h"
int main(void){
show();
return 0;
}
build:
g++ -c -std=c++0x main.cpp
nvcc -arch=sm_20 -c myFunctions.cu
g++ -L/usr/local/cuda/lib64 -lcudart -o test main.o myFunctions.o
I'm trying to run the following simple example from Xcode4:
#include <boost/mpi/environment.hpp>
#include <boost/mpi/communicator.hpp>
#include <iostream>
namespace mpi = boost::mpi;
int main(int argc, char* argv[])
{
mpi::environment env(argc, argv);
mpi::communicator world;
std::cout << "I am process " << world.rank() << " of " << world.size()
<< "." << std::endl;
return 0;
}
I've added libboost_mpi and libboost_serialization to Xcode, and compiling using the default LLVM returns :
/usr/local/include/boost/mpi/communicator.hpp:1329:9: error: call to
implicitly-deleted copy constructor of 'boost::mpi::communicator'
: comm(comm), source(source), tag(tag), ia(comm), value(value)
^ ~~~~
However, I can compile and run using
mpic++ -I/usr/local/include main.cpp -L/usr/local/lib
-lboost_mpi -lboost_serialization
Although mpic++ seems to be calling through to LLVM:
$ mpic++
i686-apple-darwin11-llvm-g++-4.2: no input files
Anyways, I tried adding mpic++ as a compiler option in Xcode 4. I can run
$ sudo opensnoop -n Xcode | grep mpicc.xcspec
and see that the spec file is being loaded by Xcode, but I don't see any MPICC option. My spec file is fairly simple:
/**
Xcode Compiler Specification for MPICC
*/
{ Type = Compiler;
Identifier = com.apple.compilers.mpicc;
BasedOn = com.apple.compilers.gcc.4_2;
Name = “MPICC”;
Version = “Default”;
Description = “MPI GNU C/C++ Compiler 4.0″;
ExecPath = “/usr/local/bin/mpicc”;
PrecompStyle = pch;
}
and it's stored in
/Applications/Xcode.app/Contents/PlugIns/Xcode3Core.ideplugin/Contents/SharedSupport/Developer/Library/Xcode/Plug-ins/LLVM GCC 4.2.xcplugin/Contents/Resources/mpicc.xcspec
So this works:
link binary with:
libmpi_cxx.dylib
libmpi.dylib
libboost_mpi.dylib
libboost_serialization.dylib
Change compiler (under build options) to LLVM GCC 4.2 (hinted at by running mpic++ directly, which reports that it's using llvm gcc 4.2 internally)
Under targets, build phases, compile sources, add the compiler option "-lm" to report that you need to link with libm. Credit to #pyCthon for pointing out mpic++ --showme:link which revealed the final library that was allowing it to build successfully from the command line