開閉原則:

對擴(kuò)展開放，對修改關(guān)閉。

增加功能是提過增加代碼來實(shí)現(xiàn)的，而不是去修改源代碼。

代碼如下:

#include <iostream> #include <string> using namespace std;class Caculaor { public:Caculaor(int a,int b,string c):a(a),b(b),myOperator(c){}int getResult(){if (myOperator.compare("+") == 0){return a + b;}else if (myOperator.compare("-") == 0){return a - b;}else if (myOperator.compare("*")==0){return a * b;}else if (myOperator.compare("/") == 0){return a / b;}}private:int a;int b;string myOperator; };void test01() {Caculaor *a = new Caculaor(10, 10, "+");cout<<a->getResult()<<endl; }int main() {test01();return 0; }

測試結(jié)果:

缺點(diǎn):
如果增加取模的運(yùn)算，需要修改getResult成員方法，如果增加新功能的情況下要修改源代碼，那么就會有出錯的可能性，我們應(yīng)該在增加新的功能時候，不能影響其他已經(jīng)完成的功能，這就是對修改關(guān)閉，對擴(kuò)展開放，叫做開閉原則。

開閉原則
代碼如下:

#include <iostream> #include <string> using namespace std;class AbstractCaculator { public:virtual int getResult() = 0;virtual void setNumber(int a, int b) = 0; };class PlusCaculator :public AbstractCaculator { public:virtual void setNumber(int a, int b){this->a = a;this->b = b;}virtual int getResult(){return a + b;}private:int a;int b; };class MinuteCaculator :public AbstractCaculator { public:virtual void setNumber(int a, int b){this->a = a;this->b = b;}virtual int getResult(){return a - b;}private:int a;int b; };class MultiplyCaculator :public AbstractCaculator { public:virtual void setNumber(int a, int b){this->a = a;this->b = b;}virtual int getResult(){return a * b;}private:int a;int b; };class DivideCaculator :public AbstractCaculator { public:virtual void setNumber(int a, int b){this->a = a;this->b = b;}virtual int getResult(){return a / b;}private:int a;int b; };//取模計(jì)算器 通過增加代碼來實(shí)現(xiàn) class MoldTakingCaculator :public AbstractCaculator { public:virtual void setNumber(int a, int b){this->a = a;this->b = b;}virtual int getResult(){return a % b;}private:int a;int b; };void test01() {AbstractCaculator *a = new PlusCaculator;a->setNumber(10, 10);cout << a->getResult() << endl; }int main() {test01();return 0; }

測試結(jié)果:

總結(jié)

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