4번째줄에서 Declaration syntax error 라고나옵니다. 어떻게 하죠?
책에껄 그래도 따라했는데, 에러가 나거든요.
책은 on to c++ 이구요. 해결책좀 가르쳐 주십시오

#include <iostream.h>
#include <conio.h>

double box_volume {double h, double w, double l){return h*w*l;}
main()
{       double height, width, depth;
        while (cin >> height << width >> depth)
                cout << "The volume of a"
                << height << " by" << width << "by" << depth
                << "box car is " << box_volume (height, width, depth)
                << endl;
        cout << "You appear to have finished." << endl;
        getch()
}