c++ 类

#include<iostream>
using namespace std;
class Box
{
public:
Box(int h,int w,int len):height(h),width(w),length(len){}
int volume();
private:
int height;
int width;
int length;
};
int Box::volume()
{
return (height*width*length);
}
int main()
{
Box a[3]={
a[0]=(12,45,45),
a[1]=(14,12,17),
a[2]=(14,14,74)
};
cout<<"the volume of box1 is"<<a[0].volume()<<endl;
cout<<"the volume of box2 is"<<a[1].volume()<<endl;
cout<<"the volume of box3 is"<<a[2].volume()<<endl;
return 0;
}

我只知道这儿有问题 请帮我改正 并说明理由 谢谢！

int main()
{
Box a[3]={
Box(12,45,45),
Box(14,12,17),
Box(14,14,74)
};
cout<<"the volume of box1 is "<<a[0].volume()<<endl;
cout<<"the volume of box2 is "<<a[1].volume()<<endl;
cout<<"the volume of box3 is "<<a[2].volume()<<endl;
return 0;
}