#include <iostream>
#include <string>
#include <vector>
#include <array>
#include <tuple>
#include <initializer_list>
using std::cout;
using std::cin;
using std::endl;
using std::string;
using std::initializer_list;
using namespace std;
//定義一個測量代碼運行時間模板
template <class T>
void measure(T&& func)
{
using namespace std::chrono;
auto start = system_clock::now();
func();
duration<double> diff = system_clock::now() - start;
cout << "elapsed: " << diff.count() << "seconds: " << endl;
}
void func()
{
long long s = 0;
for (int i = 0; i < 100000; i++)
{
s += i;
}
cout << s << endl;
}
//測試多線程分擔任務..
void funMultex(long start,long end,long& nans)
{
int ann = 0;
for (int i = start; i < end; i++)
{
ann += i;
}
nans = ann;
}
long funSum(long start,long end)
{
long s = 0;
for (int i = start; i < end; i++)
{
s += i;
}
return s;
}
const long kLong = 1000000000;
int main()
{
//時間
measure([]() {
long long s = 0;
for (int i = 0; i < 1000000; i++)
{
s += i;
}
cout << s << endl;
});
//正常傳參.
measure(func);
measure([]() {
long ands1, ands2;
//測試雙分任務.
thread sum1 = thread(funMultex, 0, kLong / 2, std::ref(ands1));
thread sum2 = thread(funMultex, kLong / 2, kLong, std::ref(ands2));
sum1.join();
sum2.join();
cout << "輸出結果：" << (ands1 + ands2) << endl;
});
measure([]() {
long ans;
funMultex(0, kLong, ans);
cout << "輸出結果2： " << ans << endl;
});
measure([]() {
const long k = 4;
//這個記錄了每個線程的結果.
vector<future<long>> vf;
vf.reserve(k);
for (int i = 0; i < k; i++)
{
//這裏使用異步的形式，使用vf來保存結果
vf.push_back(async(funSum, i == 0 ? 0 : (kLong / k)*i, (kLong / k)*(i + 1)));
}
long ans = 0;
for (int i = 0; i < k; i++)
{
ans += vf[i].get();
}
cout << "五個線程計算的結果： " << ans << endl;
});
measure([]() {
long ans;
funMultex(0, kLong, ans);
cout << "輸出結果2： " << ans << endl;
});
system("pause");
return 0;
}
src data: i am a hero
move str2: i am a hero
i am a hero bag
499999500000
elapsed: 0.0022347seconds:
4999950000
elapsed: 0.0005302seconds:
輸出結果：-1243309312
elapsed: 1.02473seconds:
輸出結果2： -1243309312
elapsed: 2.02655seconds:
五個線程計算的結果： -1243309312
elapsed: 0.536332seconds:
輸出結果2： -1243309312
elapsed: 2.04541seconds:
請按任意鍵繼續. . .