指向C++类

指向类的指针

指向C++类的指针与指向结构体的指针以及指向类的成员的访问方式完全相同，您使用成员访问运算符->运算符，就像您使用指向结构体的指针一样。此外，与所有指针一样，您必须在使用指针之前初始化它。

指向类的指针示例

让我们尝试以下示例来理解指向类的指针的概念：

#include <iostream>
 
using namespace std;

class Box {
   public:
      // Constructor definition
      Box(double l = 2.0, double b = 2.0, double h = 2.0) {
         cout <<"Constructor called." << endl;
         length = l;
         breadth = b;
         height = h;
      }
      double Volume() {
         return length * breadth * height;
      }
      
   private:
      double length;     // Length of a box
      double breadth;    // Breadth of a box
      double height;     // Height of a box
};

int main(void) {
   Box Box1(3.3, 1.2, 1.5);    // Declare box1
   Box Box2(8.5, 6.0, 2.0);    // Declare box2
   Box *ptrBox;                // Declare pointer to a class.

   // Save the address of first object
   ptrBox = &Box1;

   // Now try to access a member using member access operator
   cout << "Volume of Box1: " << ptrBox->Volume() << endl;

   // Save the address of second object
   ptrBox = &Box2;

   // Now try to access a member using member access operator
   cout << "Volume of Box2: " << ptrBox->Volume() << endl;
  
   return 0;
}

当以上代码编译并执行时，会产生以下结果：

Constructor called.
Constructor called.
Volume of Box1: 5.94
Volume of Box2: 102