设计模式——简单工厂
第一版： 简单实现
在int main 主函数中读取数据，使用switch语句分别进行操作。不同操作用类实现。
#include <iostream> using namespace std; static int num_a; static int num_b; static char op; void input_num() { cout<<"input_num : "; } void input_op() { cout<<"input_op : "; } class Op_Add { public: int calc() { return num_a+num_b; } }; class Op_Minus { public: int calc() { return num_a-num_b; } }; class Op_Mut { public: int calc() { return num_a*num_b; } }; class Op_Div { public: int calc() { if(num_b) { return num_a/num_b; } else { cout<<"分母为0"<<endl; return 0; } } }; int main(int argc, char *argv[]) { input_num(); cin>>num_a; input_num(); cin>>num_b; input_op(); cin>>op; switch (op) { case '+': { Op_Add op1; cout<<"result is "<<op1.calc()<<endl; break; } case '-': { Op_Minus op2; cout<<"result is "<<op2.calc()<<endl; break; } case '*': { Op_Mut op3; cout<<"result is "<<op3.calc()<<endl; break; } case '/': { Op_Div op4; cout<<"result is "<<op4.calc()<<endl; break; } default: break; } return 0; }
第二版：输入数据和计算结果分离
使用Input类输入数据，operation类实现计算。
int main主函数语句变少。
#include <iostream> using namespace std; //依据使用习惯，输入数字，再输入运算符 //使用静态变量存储要进行操作的数和符号 //Input类从终端读取数据 static int num_a=0; static int num_b=0; static char op; class Input { public: void input_num(); void input_op(); //static int num_a; //static int num_b; //char op; istream& set_num_a(istream& is); istream& set_num_b(istream& is); istream& set_op(istream& is); void read_data() { set_num_a(cin); cout<<"input num_a"<<endl; set_num_b(cin); cout<<"input num_b"<<endl; set_op(cin); cout<<"input op"<<endl; cout<<"input done"<<endl; } }; void Input::input_num() { cout<<"input_num : "; } void Input::input_op() { cout<<"input_op : "; } istream& Input::set_num_a(istream& is) { this->input_num(); is >> num_a; //this->num_a = _a; } istream& Input::set_num_b(istream& is) { this->input_num(); is >> num_b; //this->num_b = _b; } istream& Input::set_op(istream& is) { this->input_op(); is >> op; //this->op = _op; } class Op_four //貌似没用的纯虚类 { public: virtual int calc()=0; } ; class Op_Add: public Op_four { public: int calc() { cout<<"num_a "<<num_a<<endl; cout<<"num_b "<<num_b<<endl; return num_a+num_b; } }; class Op_Minus: public Op_four { public: int calc() { return num_a-num_b; } }; class Op_Mut: public Op_four { public: int calc() { return num_a*num_b; } }; class Op_Div: public Op_four { public: int calc() { if(num_b) { return num_a/num_b; } else { cout<<"分母为0"<<endl; return 0; } } }; class Op_sqrt: public Op_four { public: int calc() { if(num_a >=0 ) { //开更号(假装完成) cout<<"开更号"<<endl; } } }; class Operation //运算类 { public: int get_result(int _a,int _b,char _op) { int result; switch (_op) { case '+': { Op_Add op1; cout<<"result is "<<op1.calc()<<endl; break; } case '-': { Op_Minus op2; cout<<"result is "<<op2.calc()<<endl; break; } case '*': { Op_Mut op3; cout<<"result is "<<op3.calc()<<endl; break; } case '/': { Op_Div op4; cout<<"result is "<<op4.calc()<<endl; break; } case 's': { Op_sqrt op5; cout<<"result is "<<op5.calc()<<endl; } default: break; } } }; int main(int argc, char *argv[]) { Input input; input.read_data(); Operation op1; op1.get_result(num_a,num_b,op); return 0; }
第三版：
简单工厂模式：产品和工厂类。产品为抽象类，可以派生出不同的产品，工厂类中有switch语句可以进行判断。
#include <iostream> using namespace std; //先输入运算符，再输入数据 //定以四则运算的抽象类，作为父类，具有操作数字段 class Op_four// 抽象类 { private: int _num_a=0; int _num_b=0; public: virtual int calc()=0;//重载函数 //获取运算符 int get_num_a() { return _num_a; } int get_num_b() { return _num_b; } //设置操作数 void set_num_a(istream& is) { cout<<"input_num : "; is >> this->_num_a ; } void set_num_b(istream& is) { cout<<"input_num : "; is >> this->_num_b ; } } ; class Op_Add: public Op_four { public: int calc() { //cout<<"num_a "<<num_a<<endl; //cout<<"num_b "<<num_b<<endl; return get_num_a()+get_num_b(); } }; class Op_Minus: public Op_four { public: int calc() { return get_num_a()- get_num_b(); } }; class Op_Mut: public Op_four { public: int calc() { return get_num_a()*get_num_b(); } }; class Op_Div: public Op_four { public: int calc() { if(get_num_b()) { return get_num_a()/get_num_b(); } else { cout<<"分母为0"<<endl; return 0; } } }; /*class Op_sqrt: public Op_four { public: int calc() { if(num_a >=0 ) { //开更号 cout<<"开更号"<<endl; } } };*/ class OperationFactory //运算工厂类 { public: int get_result(char _op) { int result; switch (_op) { case '+': { Op_Add op1; op1.set_num_a(cin); op1.set_num_b(cin); cout<<"result is "<<op1.calc()<<endl; break; } case '-': { Op_Minus op2; op2.set_num_a(cin); op2.set_num_b(cin); cout<<"result is "<<op2.calc()<<endl; break; } case '*': { Op_Mut op3; op3.set_num_a(cin); op3.set_num_b(cin); cout<<"result is "<<op3.calc()<<endl; break; } case '/': { Op_Div op4; op4.set_num_a(cin); op4.set_num_b(cin); cout<<"result is "<<op4.calc()<<endl; break; } /*case 's': { Op_sqrt op5; cout<<"result is "<<op5.calc()<<endl; }*/ default: break; } } }; int main(int argc, char *argv[]) { OperationFactory *of=new OperationFactory(); //输入要进行的运算符号 of->get_result('-'); delete of; return 0; }
第四版：优化数据读入，在产品的构造函数中进行数据读取
#include <iostream> //工厂模式 using namespace std; class Operation//产品类 { private: int _num_a=0; int _num_b=0; public: void set_num(istream& is) { cout<<"input num_a: "; is>>_num_a; cout<<"input num_b: "; is>>_num_b; } Operation() { set_num(cin);//在构造产品时输入数据 } int get_num_a() { return _num_a; } int get_num_b() { return _num_b; } virtual int calc()=0; }; class Op_Add:public Operation { public: int calc() { return get_num_a()+get_num_b(); } }; class Factory { public: int creat()//在工厂中获得运算符 { char op; cout<<"input op: "; cin>>op; switch(op) { case '+': { Operation *op1=new Op_Add(); //Op_Add *op1 = new Op_Add(); cout<<"result is "<<op1->calc(); delete op1; break; } case '-': { break; } default: { cout<<"do not support"<<endl; break; } } } }; int main(int argc, char *argv[]) { Factory *fac = new Factory(); fac->creat(); delete fac; return 0; }
