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Classes & Objects. 2008/03. 執行結果. Welcome to the Grade Book. 1.1 定義一個類別函數. #include<iostream.h> class GradeBook { public: void printMessage() { cout <<"Welcome to the Grade Book!"<<endl; } }; void main() {
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Classes & Objects 2008/03
執行結果 Welcome to the Grade Book 1.1 定義一個類別函數 #include<iostream.h> class GradeBook { public: void printMessage() { cout <<"Welcome to the Grade Book!"<<endl; } }; void main() { GradeBook myGB; myGB.printMessage(); } //定義一個GradeBook的class //GradeBook類別包含一個成員函數 printMessage //程式執行時，會自動呼叫main函數 //建立一個GradeBook類別的物件，叫做 myGB //使用點符號( . )來呼叫成員函數 printMessage
執行結果 Please enter the course name: Math101 Introduction to C++ Welcome to the grade book for Math101 Introduction to C++ ! 1.2 定義一個有參數的類別函數 #include<iostream> #include<string> using namespace std; class GradeBook { public: void printMessage(string courseName) { cout<<"Welcome to the grade book for\n"<< courseName <<"!"<<endl; } }; int main() { string course; GradeBook myGB; cout<<"Please enter the course name:"<< endl; getline(cin,course); cout<<endl; myGB.printMessage(course); return 0; } //定義一個GradeBook的class //GradeBook類別包含一個成員函數 printMessage //由於cin遇到space鍵會停止讀取，因此使用 getline函數來輸入字元 //course變數當成參數傳給 printMessage 函數
1.3 資料成員、set函數、get函數 #include<iostream> #include<string> using namespace std; class GradeBook { public: void setCourseName( string name) { courseName=name; } string getCourseName() { return courseName; } void printMessage() { cout<< "Welcome to the grade book for\n" << getCourseName() << "!" << endl; } private: string courseName; }; // setCourseName接收一個參數，利用此參數設定 courseName的值 // getCourseName回傳 courseName的值 // private 表示只能被類別的成員函數所存取 // 因此 courseName 只能使用在setCourseName、getCourseName與 //printMessage函數
執行結果 Please enter the course name: Math101 Introduction to C++ Welcome to the grade book for Math101 Introduction to C++ ! 1.3 資料成員、set函數、get函數 int main() { string course; GradeBook myGB; cout<<"Please enter the course name:" << endl; getline( cin,course ); myGB.setCourseName(course); cout << endl; myGB.printMessage(); return 0; } // 呼叫setCourseName 函數來設定值
1.4 初始化物件---建構子 #include<iostream> #include<string> using namespace std; class GradeBook { public: GradeBook(string name) { setCourseName(name); } void setCourseName( string name) { courseName=name; } string getCourseName() { return courseName; } void printMessage() { cout<< "Welcome to the grade book for\n" << getCourseName() << "!" << endl; } private: string courseName; }; // 建立GradeBook類別的建構子 //建構子名稱要與類別名稱相同
執行結果 gradeBook1 created for course: Math101 Introduction to C++ gradeBook2 created for course: Math102 Data Structures in C++ 1.4 初始化物件---建構子 int main() { GradeBook myGB1("Math101 Introduction to C++"); //建立物件時，傳入參數設定初始值 GradeBook myGB2("Math102 Data Structures in C++"); cout<<"gradeBook1 created for course:" << myGB1.getCourseName() <<"\ngradeBook2 created for course:" << myGB2.getCourseName() << endl; return 0; }
