Question

对于下面的编译错误，任何评论都表示赞赏。虽然我的问题类似于其他主题：pthread function from a class，但我仍然无法解决我的问题。我仍然不是那种指针，以及C＆amp; S中的线程编程。 C ++。

错误

../src/Main.cpp: In function ‘int main(int, char**)’:
../src/Main.cpp:22: error: invalid conversion from ‘unsigned int* (*)(void*)’ to ‘void* (*)(void*)’
../src/Main.cpp:22: error:   initializing argument 3 of ‘int pthread_create(pthread_t*, const pthread_attr_t*, void* (*)(void*), void*)’
make: *** [src/Main.o] Error 1

Main.cpp的

#include <process.h>
#include "ThreadInstance.hpp"
#include <iostream>
#include <fstream>
using namespace std;

int main(int argc, char** argv)
{
    pthread_mutex_t mutex;
    int ht1;
    pthread_t threadId1;
    pthread_attr_t attr1;

    pthread_mutex_init(&mutex, NULL);
    pthread_attr_init(&attr1);
    pthread_attr_setdetachstate(&attr1, PTHREAD_CREATE_DETACHED);

    ht1 = pthread_create(&threadId1,
            &attr1,
            &ThreadInstance::ThreadEntryPoint,
            //(void *)readThread);
            NULL);

    unsigned long rc = 0;
    rc = pthread_join(ht1, NULL);

    return 0;
}

ThreadInstance.hpp

#ifndef _SCENE_CLASSIFY_THREAD_H
#define _SCENE_CLASSIFY_THREAD_H

#ifndef STDCALL
#define STDCALL __attribute__((stdcall))
#endif

using namespace std;

class ThreadInstance
{
    public:
        ThreadInstance();
        ThreadInstance(int camNum);

        void startUp();

        static unsigned STDCALL* ThreadEntryPoint(void* pThis)
        {
            //static unsigned __stdcall ThreadEntryPoint(void* pThis) {
            ThreadInstance *ptr = (ThreadInstance*) pThis;
            ptr->startUp();
            //return 1; // Returns error "invalid conversion from ‘int’ to ‘unsigned int*’" when the function is declared as pointer.
                            // Since returning either 1 or 0, 
                            // compile error still occurs. 
                            // So this return value should not be the cause.

            return 0; 
        }
        ~ThreadInstance();
};
#endif

注意：只显示必要的部分

Answer 1

您的ThreadEntryPoint必须返回void*。

错误表示预期的类型，这是您需要使用的函数指针类型。

Answer 2

start函数返回void*并取void*。你的回复unsigned int*。

更改方法以返回指向void的指针。

“使用pthread_create问题从”无效转换“

2 个答案: