傳遞對執行緒的引用

你不能將引用（或 const 引用）直接傳遞給執行緒，因為 std::thread 將複製/移動它們。相反，使用 std::reference_wrapper：

void foo(int& b)
{
    b = 10;
}

int a = 1;
std::thread thread{ foo, std::ref(a) }; //'a' is now really passed as reference

thread.join();
std::cout << a << '\n'; //Outputs 10

void bar(const ComplexObject& co)
{
    co.doCalculations();
}

ComplexObject object;
std::thread thread{ bar, std::cref(object) }; //'object' is passed as const&

thread.join();
std::cout << object.getResult() << '\n'; //Outputs the result