c/c++语言开发共享《大话设计模式》之简单工厂模式

 1 #ifndef _calculator_h_  2 #define _calculator_h_  3 #include <string>  4   5 struct calculator {  6     calculator() = default;  7     calculator(double lnum, double rnum)   8         :leftnumber(lnum), rightnumber(rnum), result(0){}  9     ~calculator(){} 10  11     virtual double getresult() = 0; //基类中可实现也可不实现 12 protected: 13     double leftnumber; 14     double rightnumber; 15     double result; 16 }; 17  18 /* 19 关于继承方式： 20     public     -- 属性不变 21     protected  -- public变成protected 22     private    -- 都变成private 23 */ 24 class calculatoradd :public calculator 25 { 26 public: 27     calculatoradd() = default; 28     calculatoradd(double lnum, double rnum)  29         :calculator(lnum, rnum){} 30     ~calculatoradd(){}; 31     //加 32     virtual double getresult(); 33 }; 34 class calculatorsub :public calculator 35 { 36 public: 37     calculatorsub() = default; 38     calculatorsub(double lnum, double rnum)  39         :calculator(lnum, rnum){} 40     ~calculatorsub(){}; 41     //减 42     virtual double getresult(); 43 }; 44 class calculatormul :public calculator 45 { 46 public: 47     calculatormul() = default; 48     calculatormul(double lnum, double rnum)  49         :calculator(lnum, rnum){} 50     ~calculatormul(){}; 51     //乘 52     virtual double getresult(); 53 }; 54 class calculatordiv :public calculator 55 { 56 public: 57     calculatordiv() = default; 58     calculatordiv(double lnum, double rnum) 59         :calculator(lnum, rnum){} 60     ~calculatordiv(){}; 61     //除 62     virtual double getresult(); 63 }; 64  65 struct factorycalculator { 66     factorycalculator() = default; 67     factorycalculator(std::string op, double num1, double num2); 68     double getresult(){ return p->getresult(); }//简短函数默认inline 69 private: 70     std::string operate; 71     double number1; 72     double number2; 73     calculator *p; 74 }; 75  76 #endif

 1 #include "calculator.h"  2 #include <iostream>  3   4 using namespace std; //通常，using只出现在源文件中，而不出现在头文件中  5   6 double calculator::getresult()  7 {  8     cout << "message print in calculator::getresult" << endl;  9     return 0.0; 10 } 11  12 double calculatoradd::getresult() 13 { 14     calculator::getresult();//我曾经来过 15  16     result = leftnumber + rightnumber; 17     return result; 18 } 19 double calculatorsub::getresult() 20 { 21     calculator::getresult(); 22  23     result = leftnumber - rightnumber; 24     return result; 25 } 26 double calculatormul::getresult() 27 { 28     calculator::getresult(); 29  30     result = leftnumber * rightnumber; 31     return result; 32 } 33 double calculatordiv::getresult() 34 { 35     calculator::getresult(); 36  37     if (rightnumber == 0){ 38         cout << "division cannot be zero" << endl; 39         return -1; 40     } 41     result = leftnumber / rightnumber; 42     return result; 43 } 44  45 //如果函数体太长，则初始化列表就写在源文件（初始化列表必须跟函数体） 46 factorycalculator::factorycalculator(string op, double num1, double num2)  47     :operate(op), number1(num1), number2(num2) 48 { 49     char flag = operate[0]; 50     switch (flag) 51     { 52     case '+': 53         p = new calculatoradd(number1, number2); 54         break; 55     case '-': 56         p = new calculatorsub(number1, num2); 57         break; 58     case '*': 59         p = new calculatormul(number1, number2); 60         break; 61     case '/': 62         p = new calculatordiv(number1, number2); 63         break; 64     default: 65         break; 66     } 67 }

 1 #include "calculator.h"  2 #include <iostream>  3   4 using namespace std;  5   6 int main()  7 {  8     factorycalculator *factorycalculaotr = new factorycalculator("+", 1, 2);  9     factorycalculator *factorycalculaotr2 = new factorycalculator("-", 1, 2); 10     factorycalculator *factorycalculaotr3 = new factorycalculator("*", 1, 2); 11     factorycalculator *factorycalculaotr4 = new factorycalculator("/", 1, 2); 12     cout << factorycalculaotr->getresult() << endl; 13     cout << factorycalculaotr2->getresult() << endl; 14     cout << factorycalculaotr3->getresult() << endl; 15     cout << factorycalculaotr4->getresult() << endl; 16  17     system("pause"); 18 }