正确的线程调用语法？ 错误：没有匹配调用std :: thread :: thread（ <brace-enclosed initializer list> ）

Question

I'm trying to create a thread which runs a class function. The place where I think I'm doing something wrong is near the bottom in main where I've got RowChecker r0(puz, 0, s); thread rt0 {r0.check()}; RowChecker r0(puz, 0, s); thread rt0 {r0.check()}; . My compiler (g++) tells me that there's no matching function for call to 'std::thread::thread(<brace-enclosed initializer list>)' So I understand that I'm not making the call correctly. What is the proper way to format this call to make a new thread?

#include <iostream>
#include <thread>

using namespace std;

class Sum
{
private:
    int sum;
public:
    Sum();
    int getSum();
    void addSum();
};

class RowChecker
{
private:
    int puz[9][9];
    int myRow;
    Sum* sum;
public:
    RowChecker(int puzzel[9][9], int row, Sum* shared);
    void check();
};

Sum::Sum() {
    sum = 0;
}

int Sum::getSum() {
    return sum;
}

void Sum::addSum() {
    ++sum;
}

RowChecker::RowChecker(int puzzel[9][9], int row, Sum* shared) {
    for (int i=0; i<9; ++i) {
        for (int j=0; j<9; ++j) {
            puz[i][j] = puzzel[i][j];
        }
    }
    myRow = row;
    sum = shared;
}

void RowChecker::check() {
    char table[] = {0,0,0, 0,0,0, 0,0,0};
    for (int i=0; i<9; ++i) {
        if (puz[i][myRow]<10 && puz[i][myRow]>=0) {
            table[puz[i][myRow]] = 1;
        }
    }
    for (int i=0; i<9; ++i) {
        if (table[i]==0) {
            return;
        }
    }
    sum->addSum();
}

void readPuzzel(int puz[9][9]){
    for (int i=0; i<9; ++i) {
        for (int j=0; j<9; ++j) {
            puz[i][j] = rand() % 10;
        }
    }
}

int main()
{
    Sum s;

    int puz[9][9];
    readPuzzel(puz);

    RowChecker r0(puz, 0, &s);

    thread rt0 {r0.check()};

    rt0.join();

    cout << "Sum s is " << s.getSum() << endl;

    return 0;
}

Sorry for the length. Also, I am aware that passing arrays around is a great way to invite bugs in. I'm planning to switch things over to vectors.

Answer 1

You need to pass a function to the constructor of thread . In your code, you are calling r.check() and passing the result to the constructor of thread , and a constructor which takes such an argument does not exist, hence the error.

The thread constructor takes a function and arguments. And in the case of a member function, the first argument is the this pointer. So for your code you need:

thread rt0 { &RowChecker::check, &r0 };

That will call RowChecker::check on r0 .