#include <iostream>
using namespace std;
struct point
{
    double x,y;//交点坐标
};

class line
{
private:
    double m,b;//m为斜率，b为截距
    point pt;//pt为交点
public:
    void set_line_data();
    void show_line_data();
    void calc_pt(line);
};

void line::set_line_data()
{
    cout<<"please input m(xielv):";
    cin>>m;
    cout<<"please input b(jieju):";
    cin>>b;
}
void line::show_line_data()
{
    cout<<"m="<<m<<",b="<<b<<endl;
}
void line::calc_pt()
{
    pt.x=(crossing_line.b-b)/(m-crossing_line.m);
    pt.y=m*pt.x+b;
    cout<<"the two lines crossing point is:("<<pt.x<<","<<pt.y<<")"<<endl;

}

int main()
{
    line line1,line2;
    cout<<"please input line1:\n"; line1.set_line_data();
cout<<"please input line2:\n"; line2.set_line_data();
cout<<"line1:\n";   line1.show_line_data();
cout<<"line2:\n";   line2.show_line_data();
line1.calc_pt(line2);
return 0;
}

错误提示是：
--------------------Configuration: example2 - Win32 Debug--------------------
Compiling...
example2.cpp
d:\my_c_documents\example\example2.cpp(31) : error C2511: 'calc_pt' : overloaded member function 'void (void)' not found in 'line'
        d:\my_c_documents\example\example2.cpp(9) : see declaration of 'line'
执行 cl.exe 时出错.

example2.obj - 1 error(s), 0 warning(s)