樓主應該翻譯：https://thispointer.com/category/multithreading/

轉載來自：https://blog.csdn.net/lijinqi1987/article/details/78404092

要將引數傳遞給執行緒的可關聯物件或函式，只需將引數傳遞給std::thread建構函式。

預設情況下，所有的引數都將複製到新執行緒的內部儲存中。

#include <iostream>
#include <string>
#include <thread>
void threadCallback(int x, std::string str)
{
    std::cout 
 
<< "Passed Number = " << x << std::endl;
    std::cout << "Passed String = " << str << std::endl;
}
int main()
{
    int x = 10;
    std::string str = "Sample String";
    std::thread threadObj(threadCallback, x, str);
    threadObj.join();
    return 0;
}

不要將變數的地址從本地堆疊傳遞給執行緒的回撥函式。

#include <iostream>
#include <thread>
void newThreadCallback(int* p)
{
    std::cout << "Inside Thread :  "" : p = " << p << std::endl;
    std::chrono::milliseconds dura(1000);
    std::this_thread::sleep_for(dura);
    
 
*p = 19;
}
void startNewThread()
{
    int i = 10;
    std::cout << "Inside Main Thread :  "" : i = " << i << std::endl;
    std::thread t(newThreadCallback, &i);
    t.detach();
    std::cout << "Inside Main Thread :  "" : i = " << i << std::endl;
}
int main()
{
    startNewThread();
    std::chrono::milliseconds dura(2000);
    std::this_thread::sleep_for(dura);
    return 0;
}

同樣的，在傳遞指向堆記憶體的指標給heap時，因為某些執行緒可能在新執行緒嘗試訪問它之前刪除該記憶體。
在這種情況下，訪問無效地址可能會導致不可預測的行為。

#include <iostream>
#include <thread>
void newThreadCallback(int* p)
{
    std::cout << "Inside Thread :  "" : p = " << p << std::endl;
    std::chrono::milliseconds dura(1000);
    std::this_thread::sleep_for(dura);
    *p = 19;
    std::cout << *p << std::endl;
}
void startNewThread()
{
    int* p = new int();
    *p = 10;
    std::cout << "Inside Main Thread :  "" : *p = " << *p << std::endl;
    std::thread t(newThreadCallback, p);
    t.detach();
    delete p;
    p = NULL;
}
int main()
{
    startNewThread();
    std::chrono::milliseconds dura(2000);
    std::this_thread::sleep_for(dura);
    return 0;
}

給執行緒傳遞引用

由於引數被複制到新的執行緒堆疊，所以，如果想通過常用的方式傳遞引用，如：

#include <iostream>
#include <thread>

void threadCallback(int const& x) {
    int& y = const_cast<int&>(x);
    y++;
    std::cout << "Inside Thread x = " << x << std::endl;
}

int main() {
    int x = 9;
    std::cout << "In Main Thread : Before Thread Start x = " << x << std::endl;
    std::thread threadObj(threadCallback, x);
    threadObj.join();
    std::cout << "In Main Thread : After Thread Joins x = " << x << std::endl;
    return 0;
}

即使threadCallback接受引數作為引用，但是並沒有改變main中x的值，線上程引用外它是不可見的。
這是因為執行緒函式threadCallback中的x是引用複製在新執行緒的堆疊中的臨時值。

如何修改：

使用 std::ref

#include <iostream>
#include <thread>

void threadCallback(int const& x) {
    int& y = const_cast<int&>(x);
    y++;
    std::cout << "Inside Thread x = " << x << std::endl;
}

int main() {
    int x = 9;
    std::cout << "In Main Thread : Before Thread Start x = " << x << std::endl;
    std::thread threadObj(threadCallback, std::ref(x));
    threadObj.join();
    std::cout << "In Main Thread : After Thread Joins x = " << x << std::endl;
    return 0;
}

指定一個類的成員函式的指標作為執行緒函式
將指標傳遞給成員函式作為回撥函式，並將指標指向物件作為第二個引數

#include <iostream>
#include <thread>
class DummyClass {
public:
    DummyClass()
    {}
    DummyClass(const DummyClass& obj)
    {}
    void sampleMemberFunction(int x)
    {
        std::cout << "Inside sampleMemberFunction " << x << std::endl;
    }
};
int main() {

    DummyClass dummyObj;
    int x = 10;
    std::thread threadObj(&DummyClass::sampleMemberFunction, &dummyObj, x);
    threadObj.join();
    return 0;
}