20

私はこれらのファイルを持っています

consumer.cpp
consumer.hpp
defines.hpp
main.cpp
makefile
producer.cpp
producer.hpp

ここにファイル define.hpp があります

#ifndef DEFINES_HPP
#define DEFINES_HPP

#include <cassert>
#include <pthread.h> 
#include <queue>
#include <stdlib.h>
#include <string>
#include <unistd.h>

pthread_mutex_t set_queue_mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t  condition_var = PTHREAD_COND_INITIALIZER;

std::queue<int> q;

#endif // DEFINES_HPP

この define.hpp ファイルは、producer.hpp および consumer.hpp に含まれています。Producer.hpp および consumer.hpp ファイルは、それぞれ producer.cpp および consumer.cpp に含まれ、main.cpp にはまだ含まれていません。コンパイルするとエラーが発生します。

g++ -o main producer.cpp consumer.cpp main.cpp producer.hpp consumer.hpp defines.hpp -lpthread -ggdb
/tmp/ccctuRp7.o: In function `__gnu_cxx::new_allocator<int>::destroy(int*)':
/home/vardan/test/consumer.cpp:8: multiple definition of `set_queue_mutex'
/tmp/cciGccft.o:/home/vardan/test/producer.cpp:8: first defined here
/tmp/ccctuRp7.o: In function `std::deque<int, std::allocator<int> >::front()':
/home/vardan/test/consumer.cpp:12: multiple definition of `condition_var'
/tmp/cciGccft.o:/home/vardan/test/producer.cpp:11: first defined here
/tmp/ccctuRp7.o: In function `global::consumer::entry_point(void*)':
/home/vardan/test/consumer.cpp:17: multiple definition of `q'
/tmp/cciGccft.o:/home/vardan/test/producer.cpp:17: first defined here
/tmp/ccKCxptM.o: In function `main':
/home/vardan/test/main.cpp:8: multiple definition of `set_queue_mutex'
/tmp/cciGccft.o:/home/vardan/test/producer.cpp:8: first defined here
/tmp/ccKCxptM.o: In function `main':
/home/vardan/test/main.cpp:13: multiple definition of `condition_var'
/tmp/cciGccft.o:/home/vardan/test/producer.cpp:11: first defined here
/tmp/ccKCxptM.o: In function `main':
/home/vardan/test/main.cpp:25: multiple definition of `q'
/tmp/cciGccft.o:/home/vardan/test/producer.cpp:17: first defined here
collect2: error: ld returned 1 exit status
make: *** [main] Error 1

ここに私のメイクファイルがあります

main : producer.cpp consumer.cpp main.cpp producer.hpp consumer.hpp defines.hpp
    g++ -o $@ $^ -lpthread -ggdb
.PHONY : clean
clean:
    rm -rf main *.swf *.o

この問題を解決するには？

4

1 に答える 1

41

In C++ (as well as in C) there is a difference between declaring and defining things like variables. What you are doing in the header file is defining the variables, which means that every source file that includes the header file will have the definitions.

In the header file you should only declare the variables, and then in a single source file define them.

So in the header file do e.g.

extern pthread_mutex_t set_queue_mutex;
extern pthread_cond_t  condition_var;

extern std::queue<int> q;

And then in a single source file put the definitions (what you have now).

于 2013-10-30T06:56:43.597 に答える