Summary of C + + copy function, about the scope of variables and so on---shinepans

#include <iostream>using namespace Std;class circle{private:double r0;public:circle (double r) {r0 = R;cout < < R << "function called the initialization of the sphere \ n";} Circle (const circle &t) {r0 = T.r0;cout << "r=" << r0 << "Duplicate function called the sphere \ n";} Double Get_rr () {return r;} Double Getarea () {cout << "sphere surface area:" << 4 * 3.14*r0*r0;return 4 * 3.14*R0*R0;}}; Class rectangle{private:double length;double width;double height;public:rectangle (double A, double b, double c) {length = A;width = B;height = c;cout << length << "," << width << "," << height << ", the initialization of the box is called function \ n ";} Rectangle (Rectangle &n) {length = N.length;width = N.width;height = n.height;cout << height << "Copy of Box is called Count \ n ";} Double Getarea () {return (2 * length*width + 2 * length*height + 2 * width*height);}}; Class Whole{private:circle P1; Rectangle p2;double All_area;public:whole (Circle Xp1, Rectangle xp2);}; Whole::whole (Circle Xp1, Rectangle xp2):p 2 (XP2), p1 (XP1) {Double area1 =2 * P1.getarea () cout << "Two spheres of surface area are:" << area1 << endl;double area2 = P2.getarea (); cout << "cuboid surface The product is: "<< area2 << endl;all_area = area1 + area2;cout <<" Output total surface area: "<< all_area << Endl;} /*whole::whole (Whole &p):p 1 (P.P1), p2 (p.p2) {all_area=p.area1+p.area2;} /*whole::whole (Whole &p4):p (P4.P1), P (p4.p2) {cout<< "Output total surface area:"; area=p4.area;} */int Main () {double m;cout << "Please enter the value of M:"; cin >> m;double rr = m/2;circle XP1 (RR); Rectangle XP2 (2 * m, M, m); Whole (XP1, XP2); System ("pause"); return 0;}

For a copy function, there is an important error-prone place:

When defining a variable in a class:

If I define a private:double R in class circle, then the program will recognize the error and use R without initialization, so it is best to define r0, the subsequent use of R,

Here is the code that uses r:

#include <iostream>using namespace Std;class circle{private:double r;public:circle (double r) {R=r;cout<<r << "called the initialized function of the sphere \ n";}    Circle (Circle & T) {R=T.R; cout<< "r=" <<r<< "called the copied function of the sphere \ n";} Double Get_rr () {return r;} Double Getarea () {cout<< "Sphere surface area:" <<4*3.14*r*r;return 4*3.14*r*r;}; Class rectangle{private:double length;double width;double height;public:rectangle (double a,double b,double c) {length= a;width=b;height=c;cout<<length<< "," <<width<< "," <

Operation Result:


It's wrong.


Summary of C + + copy function, about the scope of variables and so on---shinepans