{"id":192,"date":"2020-08-22T21:53:27","date_gmt":"2020-08-22T13:53:27","guid":{"rendered":"https:\/\/kishere.gq\/?p=192"},"modified":"2021-01-14T10:54:22","modified_gmt":"2021-01-14T02:54:22","slug":"c%e5%a4%9a%e6%80%81","status":"publish","type":"post","link":"https:\/\/blog.kishere.cn\/?p=192","title":{"rendered":"C++\u591a\u6001"},"content":{"rendered":"

\u4ec0\u4e48\u662f\u591a\u6001?<\/h1>\n

\u591a\u6001\u7684\u610f\u601d\u5c31\u662f\u505a\u540c\u4e00\u4ef6\u4e8b\u60c5, \u4e0d\u540c\u7684\u5bf9\u8c61\u4ea7\u751f\u4e0d\u540c\u7684\u7ed3\u679c. \u6bd4\u5982\u5750\u8f66\u7684\u65f6\u5019, \u6210\u4eba\u5168\u7968, 1.2\u4ee5\u4e0b\u514d\u7968.
\n\u5176\u5b9e\u51fd\u6570\u91cd\u8f7d\u4e5f\u53ef\u4ee5\u7b97\u4f5c\u662f\u591a\u6001\u7684\u4e00\u79cd\u5f62\u5f0f.<\/p>\n

\u7ee7\u627f\u4e2d\u7684\u591a\u6001<\/h1>\n

\u51fd\u6570\u91cd\u8f7d\u6211\u4eec\u5df2\u7ecf\u8ba8\u8bba\u8fc7\u4e86, \u6240\u4ee5\u6211\u4eec\u91cd\u70b9\u6765\u770b\u770b\u5728\u7ee7\u627f\u4e2d\u5982\u4f55\u5b9e\u73b0\u591a\u6001.<\/p>\n

\u6784\u6210\u591a\u6001\u7684\u6761\u4ef6<\/h2>\n

\u5728\u7ee7\u627f\u4e2d\u6784\u6210\u591a\u6001\u9700\u8981\u6ee1\u8db3\u4e24\u4e2a\u6761\u4ef6:
\n 1. \u5fc5\u987b\u901a\u8fc7\u57fa\u7c7b\u6307\u9488\u6216\u8005\u5f15\u7528\u8c03\u7528\u865a\u51fd\u6570.<\/strong>
\n 2. \u88ab\u8c03\u7528\u7684\u5fc5\u987b\u662f\u865a\u51fd\u6570<\/strong>, \u800c\u4e14\u6d3e\u751f\u7c7b\u4e2d\u5fc5\u987b\u91cd\u5199\u865a\u51fd\u6570.<\/strong><\/p>\n

\u865a\u51fd\u6570\u4e0e\u865a\u51fd\u6570\u91cd\u5199<\/h2>\n

\u4ec0\u4e48\u662f\u865a\u51fd\u6570?
\n\u88abvirtual\u4fee\u9970\u7684\u51fd\u6570\u5c31\u662f\u865a\u51fd\u6570<\/p>\n

class Animal{\npublic:\n    virtual void func(){ \/\/\u865a\u51fd\u6570\n        cout<<\"\u4f60\u4e0d\u662f\u4eba\"<<endl;\n    }\n};\nclass Person : public Animal{\n    virtual void func(){ \/\/\u865a\u51fd\u6570\u7684\u91cd\u5199\n        cout<<\"\u4f60\u662f\u4eba\"<<endl;\n    }\n};\n<\/code><\/pre>\n
\u865a\u51fd\u6570\u7684\u91cd\u5199\u9700\u8981\u5728\u6d3e\u751f\u7c7b\u4e2d<\/strong>\u5b8c\u6210, \u800c\u4e14\u6d3e\u751f\u7c7b\u865a\u51fd\u6570\u7684\u8fd4\u56de\u503c, \u51fd\u6570\u540d\u79f0, \u53c2\u6570\u5217\u8868\u5fc5\u987b\u5b8c\u5168\u76f8\u540c.<\/strong><\/p>\n
\u865a\u51fd\u6570\u91cd\u5199\u7684\u7279\u4f8b<\/h2>\n
1.\u534f\u53d8<\/h3>\n
\u534f\u53d8\u7684\u542b\u4e49\u662f\u6d3e\u751f\u7c7b\u5728\u91cd\u5199\u865a\u51fd\u6570\u65f6, \u5176\u8fd4\u56de\u503c\u7c7b\u578b\u4e0e\u57fa\u7c7b\u865a\u51fd\u6570\u8fd4\u56de\u503c\u7c7b\u578b\u4e0d\u540c.
\n\u57fa\u7c7b\u8fd4\u56de\u57fa\u7c7b\u6307\u9488\u6216\u5f15\u7528, \u6d3e\u751f\u7c7b\u8fd4\u56de\u6d3e\u751f\u7c7b\u6307\u9488\u6216\u5f15\u7528.<\/p>\n
class A{};\nclass B:public A{};\n\nclass Animal{\npublic:\n    virtual A* func(){ \n        cout<<\"\u4f60\u4e0d\u662f\u4eba\"<<endl;\n        return new A;\n    }\n};\nclass Person : public Animal{\n    virtual B* func(){ \/\/\u8fd4\u56de\u503c\u7c7b\u578b\u4e0d\u9700\u8981\u4e00\u5b9a\u662fPerson*\u7c7b\u578b, \u4e5f\u5c31\u662f\u8bf4, \n                       \/\/\u53ea\u8981\u8fd4\u56de\u503c\u7c7b\u578b\u6784\u6210\u4e86\u7ee7\u627f, \u5c31\u53ef\u4ee5\u4f5c\u4e3a\u53d1\u751f\u534f\u53d8\u7684\u8fd4\u56de\u503c.\n        cout<<\"\u4f60\u662f\u4eba\"<<endl;\n        return new B;\n    }\n};\n<\/code><\/pre>\n
2.\u6790\u6784\u51fd\u6570<\/h3>\n
\u5982\u679c\u57fa\u7c7b\u7684\u6790\u6784\u51fd\u6570\u4e3a\u865a\u51fd\u6570\uff0c\u6b64\u65f6\u6d3e\u751f\u7c7b\u6790\u6784\u51fd\u6570\u53ea\u8981\u5b9a\u4e49\uff0c\u65e0\u8bba\u662f\u5426\u52a0virtual\u5173\u952e\u5b57\uff0c\u90fd\u4e0e\u57fa\u7c7b\u7684\u6790\u6784\u51fd\u6570\u6784\u6210\u91cd\u5199\uff0c\u867d\u7136\u57fa\u7c7b\u4e0e\u6d3e\u751f\u7c7b\u6790\u6784\u51fd\u6570\u540d\u5b57\u4e0d\u540c\u3002\u867d\u7136\u51fd\u6570\u540d\u4e0d\u76f8\u540c\uff0c\u770b\u8d77\u6765\u8fdd\u80cc\u4e86\u91cd\u5199\u7684\u89c4\u5219\uff0c\u5176\u5b9e\u4e0d\u7136\uff0c\u8fd9\u91cc\u53ef\u4ee5\u7406\u89e3\u4e3a\u7f16\u8bd1\u5668\u5bf9\u6790\u6784\u51fd\u6570\u7684\u540d\u79f0\u505a\u4e86\u7279\u6b8a\u5904\u7406\uff0c\u7f16\u8bd1\u540e\u6790\u6784\u51fd\u6570\u7684\u540d\u79f0\u7edf\u4e00\u5904\u7406\u6210destructor\u3002<\/p>\n
class Person {\npublic:\n    virtual ~Person() {\n        cout << \"~Person()\" << endl;\n    }\n};\nclass Student : public Person {\npublic:\n    virtual ~Student() {\n        cout << \"~Student()\" << endl; \n    }\n};\n\/\/ \u53ea\u6709\u6d3e\u751f\u7c7bStudent\u7684\u6790\u6784\u51fd\u6570\u91cd\u5199\u4e86Person\u7684\u6790\u6784\u51fd\u6570\uff0c\u4e0b\u9762\u7684delete\u5bf9\u8c61\u8c03\u7528\u6790\u6784\u51fd\u6570\uff0c\u624d\u80fd\u6784\u6210\u591a\u6001\uff0c\u624d\u80fd\u4fdd\u8bc1p1\u548cp2\u6307\u5411\u7684\u5bf9\u8c61\u6b63\u786e\u7684\u8c03\u7528\u6790\u6784\u51fd\u6570\u3002\n<\/code><\/pre>\n
\u7eaf\u865a\u51fd\u6570\u4e0e\u62bd\u8c61\u7c7b<\/h2>\n
\u5728\u865a\u51fd\u6570\u7684\u540e\u9762\u5199\u4e0a = 0 \uff0c\u5219\u8fd9\u4e2a\u51fd\u6570\u4e3a\u7eaf\u865a\u51fd\u6570. \u5305\u542b\u7eaf\u865a\u51fd\u6570\u7684\u7c7b\u53eb\u505a\u62bd\u8c61\u7c7b, \u62bd\u8c61\u7c7b\u4e0d\u80fd\u5b9e\u4f8b\u5316\u51fa\u5bf9\u8c61\u3002\u6d3e\u751f\u7c7b\u7ee7\u627f\u540e\u4e5f\u4e0d\u80fd\u5b9e\u4f8b\u5316\u51fa\u5bf9\u8c61\uff0c\u53ea\u6709\u91cd\u5199\u7eaf\u865a\u51fd\u6570\uff0c\u6d3e\u751f\u7c7b\u624d\u80fd\u5b9e\u4f8b\u5316\u51fa\u5bf9\u8c61\u3002\u7eaf\u865a\u51fd\u6570\u89c4\u8303\u4e86\u6d3e\u751f\u7c7b\u5fc5\u987b\u91cd\u5199.<\/p>\n
class Car{\npublic:\n    virtual void Drive() = 0;\/\/\u7eaf\u865a\u51fd\u6570\n};\n\nclass Benz :public Car{\npublic:\n    virtual void Drive(){\n        cout << \"Benz-\u8212\u9002\" << endl;\n    }\n};\n\nclass BMW :public Car{\npublic:\n    virtual void Drive(){\n        cout << \"BMW-\u64cd\u63a7\" << endl;\n    }\n};\nvoid Test(){\n    Car* pBenz = new Benz;\n    pBenz->Drive();\n    Car* pBMW = new BMW;\n    pBMW->Drive();\n}\n<\/code><\/pre>\n
\u51fd\u6570\u91cd\u8f7d\u548c\u865a\u51fd\u6570\u91cd\u5199\u7684\u533a\u522b<\/h2>\n
\u51fd\u6570\u91cd\u8f7d:<\/h3>\n
    \n
  • \u5728\u540c\u4e00\u4f5c\u7528\u57df\u4e2d<\/li>\n
  • \u5f62\u53c2\u5217\u8868(\u53c2\u6570\u4e2a\u6570 \u6216 \u7c7b\u578b \u6216 \u987a\u5e8f)\u5fc5\u987b\u4e0d\u540c<\/li>\n
  • \u51fd\u6570\u540d\u76f8\u540c<\/li>\n<\/ul>\n
    \u865a\u51fd\u6570\u91cd\u5199<\/h3>\n
      \n
    • \u5fc5\u987b\u662f\u865a\u51fd\u6570<\/li>\n
    • \u51fd\u6570\u540d \u53c2\u6570\u5217\u8868 \u8fd4\u56de\u503c\u5fc5\u987b\u76f8\u540c<\/li>\n
    • \u5206\u522b\u5728\u57fa\u7c7b\u548c\u6d3e\u751f\u7c7b\u7684\u4f5c\u7528\u57df<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"
      \u4ec0\u4e48\u662f\u591a\u6001? \u591a\u6001\u7684\u610f\u601d\u5c31\u662f\u505a\u540c\u4e00\u4ef6\u4e8b\u60c5, \u4e0d\u540c\u7684\u5bf9\u8c61\u4ea7\u751f\u4e0d\u540c\u7684\u7ed3\u679c. \u6bd4\u5982\u5750\u8f66\u7684\u65f6\u5019, \u6210\u4eba\u5168\u7968, 1.2\u4ee5\u4e0b\u514d\u7968. \u5176\u5b9e\u51fd\u6570\u91cd\u8f7d\u4e5f\u53ef\u4ee5\u7b97\u4f5c\u662f\u591a\u6001\u7684\u4e00\u79cd\u5f62\u5f0f. \u7ee7\u627f\u4e2d\u7684\u591a\u6001 \u51fd\u6570\u91cd\u8f7d\u6211\u4eec\u5df2\u7ecf\u8ba8\u8bba\u8fc7\u4e86, \u6240\u4ee5\u6211\u4eec\u91cd\u70b9\u6765\u770b\u770b\u5728\u7ee7\u627f\u4e2d\u5982\u4f55\u5b9e\u73b0\u591a\u6001. \u6784\u6210\u591a\u6001\u7684\u6761\u4ef6 \u5728\u7ee7\u627f\u4e2d\u6784\u6210\u591a\u6001\u9700\u8981\u6ee1\u8db3\u4e24\u4e2a\u6761\u4ef6: 1. \u5fc5\u987b\u901a\u8fc7\u57fa\u7c7b\u6307\u9488\u6216\u8005\u5f15\u7528\u8c03\u7528\u865a\u51fd\u6570. 2. \u88ab\u8c03\u7528\u7684\u5fc5\u987b\u662f\u865a\u51fd\u6570, \u800c\u4e14\u6d3e\u751f\u7c7b\u4e2d\u5fc5\u987b\u91cd\u5199\u865a\u51fd\u6570. \u865a\u51fd\u6570\u4e0e\u865a\u51fd\u6570\u91cd\u5199 \u4ec0\u4e48\u662f\u865a\u51fd\u6570? \u88abvirtual\u4fee\u9970\u7684\u51fd\u6570\u5c31\u662f\u865a\u51fd\u6570 class Animal{ public: virtual void func(){ \/\/\u865a\u51fd\u6570 cout<<“\u4f60\u4e0d\u662f\u4eba”<<endl; } }; class Person : public Animal{ virtual void func(){ \/\/\u865a\u51fd\u6570\u7684\u91cd\u5199 cout<<“\u4f60\u662f\u4eba”<<endl; } }; \u865a\u51fd\u6570\u7684\u91cd\u5199\u9700\u8981\u5728\u6d3e\u751f\u7c7b\u4e2d\u5b8c\u6210, \u800c\u4e14\u6d3e\u751f\u7c7b\u865a\u51fd\u6570\u7684\u8fd4\u56de\u503c, \u51fd\u6570\u540d\u79f0, \u53c2\u6570\u5217\u8868\u5fc5\u987b\u5b8c\u5168\u76f8\u540c. \u865a\u51fd\u6570\u91cd\u5199\u7684\u7279\u4f8b 1.\u534f\u53d8 \u534f\u53d8\u7684\u542b\u4e49\u662f\u6d3e\u751f\u7c7b\u5728\u91cd\u5199\u865a\u51fd\u6570\u65f6, \u5176\u8fd4\u56de\u503c\u7c7b\u578b\u4e0e\u57fa\u7c7b\u865a\u51fd\u6570\u8fd4\u56de\u503c\u7c7b\u578b\u4e0d\u540c. \u57fa\u7c7b\u8fd4\u56de\u57fa\u7c7b\u6307\u9488\u6216\u5f15\u7528, \u6d3e\u751f\u7c7b\u8fd4\u56de\u6d3e\u751f\u7c7b\u6307\u9488\u6216\u5f15\u7528. class A{}; class B:public A{}; class Animal{ public: virtual A* func(){ cout<<“\u4f60\u4e0d\u662f\u4eba”<<endl; return new A; } }; class Person : public Animal{ virtual B* func(){ \/\/\u8fd4\u56de\u503c\u7c7b\u578b\u4e0d\u9700\u8981\u4e00\u5b9a\u662fPerson*\u7c7b\u578b, \u4e5f\u5c31\u662f\u8bf4, \/\/\u53ea\u8981\u8fd4\u56de\u503c\u7c7b\u578b\u6784\u6210\u4e86\u7ee7\u627f, \u5c31\u53ef\u4ee5\u4f5c\u4e3a\u53d1\u751f\u534f\u53d8\u7684\u8fd4\u56de\u503c. cout<<“\u4f60\u662f\u4eba”<<endl; return new B; } }; 2.\u6790\u6784\u51fd\u6570 \u5982\u679c\u57fa\u7c7b\u7684\u6790\u6784\u51fd\u6570\u4e3a\u865a\u51fd\u6570\uff0c\u6b64\u65f6\u6d3e\u751f\u7c7b\u6790\u6784\u51fd\u6570\u53ea\u8981\u5b9a\u4e49\uff0c\u65e0\u8bba\u662f\u5426\u52a0virtual\u5173\u952e\u5b57\uff0c\u90fd\u4e0e\u57fa\u7c7b\u7684\u6790\u6784\u51fd\u6570\u6784\u6210\u91cd\u5199\uff0c\u867d\u7136\u57fa\u7c7b\u4e0e\u6d3e\u751f\u7c7b\u6790\u6784\u51fd\u6570\u540d\u5b57\u4e0d\u540c\u3002\u867d\u7136\u51fd\u6570\u540d\u4e0d\u76f8\u540c\uff0c\u770b\u8d77\u6765\u8fdd\u80cc\u4e86\u91cd\u5199\u7684\u89c4\u5219\uff0c\u5176\u5b9e\u4e0d\u7136\uff0c\u8fd9\u91cc\u53ef\u4ee5\u7406\u89e3\u4e3a\u7f16\u8bd1\u5668\u5bf9\u6790\u6784\u51fd\u6570\u7684\u540d\u79f0\u505a\u4e86\u7279\u6b8a\u5904\u7406\uff0c\u7f16\u8bd1\u540e\u6790\u6784\u51fd\u6570\u7684\u540d\u79f0\u7edf\u4e00\u5904\u7406\u6210destructor\u3002 class Person { public: virtual ~Person() { cout << “~Person()” << endl; } }; class Student : public Person { public: virtual ~Student() { cout << “~Student()” << endl; } }; \/\/ \u53ea\u6709\u6d3e\u751f\u7c7bStudent\u7684\u6790\u6784\u51fd\u6570\u91cd\u5199\u4e86Person\u7684\u6790\u6784\u51fd\u6570\uff0c\u4e0b\u9762\u7684delete\u5bf9\u8c61\u8c03\u7528\u6790\u6784\u51fd\u6570\uff0c\u624d\u80fd\u6784\u6210\u591a\u6001\uff0c\u624d\u80fd\u4fdd\u8bc1p1\u548cp2\u6307\u5411\u7684\u5bf9\u8c61\u6b63\u786e\u7684\u8c03\u7528\u6790\u6784\u51fd\u6570\u3002 \u7eaf\u865a\u51fd\u6570\u4e0e\u62bd\u8c61\u7c7b \u5728\u865a\u51fd\u6570\u7684\u540e\u9762\u5199\u4e0a = 0 \uff0c\u5219\u8fd9\u4e2a\u51fd\u6570\u4e3a\u7eaf\u865a\u51fd\u6570. \u5305\u542b\u7eaf\u865a\u51fd\u6570\u7684\u7c7b\u53eb\u505a\u62bd\u8c61\u7c7b, \u62bd\u8c61\u7c7b\u4e0d\u80fd\u5b9e\u4f8b\u5316\u51fa\u5bf9\u8c61\u3002\u6d3e\u751f\u7c7b\u7ee7\u627f\u540e\u4e5f\u4e0d\u80fd\u5b9e\u4f8b\u5316\u51fa\u5bf9\u8c61\uff0c\u53ea\u6709\u91cd\u5199\u7eaf\u865a\u51fd\u6570\uff0c\u6d3e\u751f\u7c7b\u624d\u80fd\u5b9e\u4f8b\u5316\u51fa\u5bf9\u8c61\u3002\u7eaf\u865a\u51fd\u6570\u89c4\u8303\u4e86\u6d3e\u751f\u7c7b\u5fc5\u987b\u91cd\u5199. class Car{ public: virtual void Drive() = 0;\/\/\u7eaf\u865a\u51fd\u6570 }; class Benz :public Car{ public: virtual void Drive(){ cout << “Benz-\u8212\u9002” << endl; } }; class BMW :public Car{ public: virtual void Drive(){ cout << “BMW-\u64cd\u63a7” << endl; } }; void Test(){ Car* pBenz = new Benz; pBenz->Drive(); Car* pBMW = new BMW; pBMW->Drive(); } \u51fd\u6570\u91cd\u8f7d\u548c\u865a\u51fd\u6570\u91cd\u5199\u7684\u533a\u522b \u51fd\u6570\u91cd\u8f7d: \u5728\u540c\u4e00\u4f5c\u7528\u57df\u4e2d \u5f62\u53c2\u5217\u8868(\u53c2\u6570\u4e2a\u6570 \u6216 \u7c7b\u578b \u6216 \u987a\u5e8f)\u5fc5\u987b\u4e0d\u540c \u51fd\u6570\u540d\u76f8\u540c \u865a\u51fd\u6570\u91cd\u5199 \u5fc5\u987b\u662f\u865a\u51fd\u6570 \u51fd\u6570\u540d \u53c2\u6570\u5217\u8868 \u8fd4\u56de\u503c\u5fc5\u987b\u76f8\u540c \u5206\u522b\u5728\u57fa\u7c7b\u548c\u6d3e\u751f\u7c7b\u7684\u4f5c\u7528\u57df<\/p>\n","protected":false},"author":1,"featured_media":196,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"footnotes":""},"categories":[11,5],"tags":[],"_links":{"self":[{"href":"https:\/\/blog.kishere.cn\/index.php?rest_route=\/wp\/v2\/posts\/192"}],"collection":[{"href":"https:\/\/blog.kishere.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.kishere.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.kishere.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.kishere.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=192"}],"version-history":[{"count":6,"href":"https:\/\/blog.kishere.cn\/index.php?rest_route=\/wp\/v2\/posts\/192\/revisions"}],"predecessor-version":[{"id":217,"href":"https:\/\/blog.kishere.cn\/index.php?rest_route=\/wp\/v2\/posts\/192\/revisions\/217"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blog.kishere.cn\/index.php?rest_route=\/wp\/v2\/media\/196"}],"wp:attachment":[{"href":"https:\/\/blog.kishere.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=192"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.kishere.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=192"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.kishere.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=192"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}