c++从入门到精通——单例模式

声明无法直接调用

#define _CRT_SECURE_NO_WARNINGS

#include<iostream>

using namespace std;

class ChairMan {
public:
  static ChairMan *getInstance() {
    return singleMan;
  }
private:
  ChairMan() { };
  ChairMan(const ChairMan &){};
  static ChairMan *singleMan;
};
ChairMan * ChairMan::singleMan = new ChairMan;
void test01(){
  /* 无法调用函数
  ChairMan c1;
  ChairMan c2;
  ChairMan *c3 = new ChairMan;*/

  
}
int main() {
  test01();
//  system("pause");
  return EXIT_SUCCESS;
}

单例模式获取

#define _CRT_SECURE_NO_WARNINGS

#include<iostream>

using namespace std;

class ChairMan {
public:
  static ChairMan *getInstance() {
    return singleMan;
  }
private:
  ChairMan() { };
  ChairMan(const ChairMan &){};
  static ChairMan *singleMan;
};
ChairMan * ChairMan::singleMan = new ChairMan;
void test01(){
  /* 无法调用函数
  ChairMan c1;
  ChairMan c2;
  ChairMan *c3 = new ChairMan;
  ChairMan *c1 = ChairMan::singleMan;*/
  ChairMan *c1 = ChairMan::getInstance();
  ChairMan *c2 = ChairMan::getInstance();
  //ChairMan *c3 = new ChairMan(*c1);
  if(c1==c2){
    cout<<"c1=c2"<<endl;
  } else{
    cout<<"c1!=c2"<<endl;
  }


}
int main() {
  test01();
//  system("pause");
  return EXIT_SUCCESS;
}

打印机案例

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
using namespace std;
class Printer{
public:
  int m_Count{0};
  static Printer* getInstance(){
    return printer;
  }
  void printText(string text){
      m_Count++;
      cout<<"m_Count,打印机被调用"<<endl;
  };
private:
  static Printer *printer;
  Printer(){
    m_Count=0;
  }
  Printer(const Printer&p){};
};
Printer *Printer::printer = new Printer;
void test01(){
  Printer *p1 = Printer::getInstance();
  p1->printText("入职证明");
  p1->printText("离职证明");
  p1->printText("加薪证明");
  p1->printText("旅游证明");
  cout<<"打印机使用次数"<<p1->m_Count<<endl;

  Printer *p2 = Printer::getInstance();
  p1->printText("还是入职证明");
  cout<<"打印机使用次数"<<p1->m_Count<<endl;



}
int main() {
  test01();
//  system("pause");
  return EXIT_SUCCESS;
}