如何在 C++ 中多线程 for 循环？

Question

How do I multi-thread a for loop in C++? Suppose I want to get such a serial calculation:

// arr is some vector with size n
int sum = 0;
for(int i = 0; i < n; i++)
    sum += arr[i];

so I want to run with 8 threads that run on 1/8 of the array, save partial sum and then add all the partial sums together. so how do I exactly do this using std::thread? thanks a lot

Answer 1

You can try something like this

    int a = 1; // replace a with your array
    std::atomic <int> sum = 0;
    auto inc = [&](){
    for(int i = 0; i < 10; i++)
        sum += a;
    };
    for(int i = 0; i < 8; i++){
        std::thread(inc).detach();
    }