32、c++ 多线程和回调函数绑定

基本思想：复习一下c++的多线程和回调函数使用

#include<functional>
#include <iostream>
#include <thread>
#include <vector>

using namespace std;

void fun(int &x, int &y) {
    cout << "x=" << x << endl << "y=" << y << endl;
    x += 100;
    y += 100;
}

void sum(vector<int>::iterator first, vector<int>::iterator end, int &result) {
    for (auto it = first; it < end; it++) {
        result = result + (*it);
    }

}

int main() {
    int a = 0;
    int b = 100;
    function<void()> f1 = bind(fun, a, ref(b));//回调函数
    f1();
    cout << "a=" << a << endl << "b=" << b << endl;

    function<void(int &, int &)> f2 = fun;

    f2(a, ref(b)); //对于绑定函数使用ref传递引用
    cout << "a=" << a << endl << "b=" << b << endl;

    int c=5;
    int &d=c;
    d=d+1;
    cout<<d<<endl;
    int e=ref(c);
    cout<<e<<endl;
    int result1 = 0;
    int result2 = 0;
    int result3 = 0;
    int result4 = 0;
    int result5 = 0;
    vector<int> sequenece;
    sequenece.reserve(8000);
    for (int i = 0; i < 8000; i++) {
        sequenece.push_back(i);
    }
    clock_t start, ends;
    start = clock();
    thread first(sum, sequenece.begin(), sequenece.begin() + 2000, ref(result1));
    thread second(sum, sequenece.begin() + 2000, sequenece.begin() + 4000, std::ref(result2));
    thread third(sum, sequenece.begin() + 4000, sequenece.begin() + 6000, std::ref(result3));
    thread fourth(sum, sequenece.begin() + 6000, sequenece.end(), std::ref(result4));
    first.join(); // 阻塞主线程，等待子线程完成   first.detach() 主线程继续执行 子线程也继续执行
    second.join();
    third.join();
    fourth.join();
    ends = clock();
    cout << (result1 + result2 + result3 + result4) << endl << ends - start << "s" << endl;
    start = clock();
    for (vector<int>::iterator it = sequenece.begin(); it != sequenece.end(); it++) {
        result5 = result5 + *it;
    }
    ends = clock();
    cout << (result5) << endl << ends - start << "s" << endl;
    return 0;
}

显示

/home/ubuntu/CLionProjects/test/cmake-build-debug/test
x=0
y=100
a=0
b=200
x=0
y=200
a=100
b=300
6
6
31996000
454s
31996000
208s

Process finished with exit code 0