[C++应用程序性能优化]列表初始化和构造函数内初始化

#include <iostream>
#include <Windows.h>

class Val
{
public:
Val(double v = 1.0)
{
for (int i = 0; i < 1000; i++)
{
d[i] = v + i;
}
}

void Init(double v = 1.0)
{
for (int i = 0; i < 1000; i++)
{
d[i] = v + i;
}
}
protected:
private:
double d[1000];
};

class Object
{
public:
// Object(double d) : v(d) {}  // 344ms
/*Object(double d)  // 687ms
{
v.Init(d);
}*/
protected:
private:
Val v;
};

int main()
{
using namespace std;
unsigned long i, ncount;
ncount = GetTickCount();
for (i = 0; i < 100000; i++)
{
Object obj(5.0);
}

ncount = GetTickCount() - ncount;
cout << ncount << "ms" << endl;
system("pause");
return 0;
}