读程序的完善

#include<iostream>
#include<stdlib.h>
using namespace std;
class A
{private:
  char *a;
 public:
  A():a(NULL){
  } //（1）__初始化_______________________________________
  A(char *aa) {
    a=new char[strlen(aa)+1];  //（2）______动态确定_a的空间____________________________________
    strcpy(a,aa);  //（3）______把aa复制给a______________________________________
  }
  ~A() {
      delete []a;
      } //（4）_____________析构函数释放a的空间______________________________
  void output(){
      cout<<a<<endl;
      }
};
int main()
{
  A a("good morning, code monkeys!");
  a.output();
  return 0;
}