类的声明和对象的定义-形式1
#include <iostream> #include <cstring> using namespace std; class Student { private: int num; char name[20]; char sex; public: void set_data(int n, char *p,char s) { num=n; strcpy(name,p); sex=s; } void display( ) { cout<<"num: "<<num<<endl; cout<<"name: " <<name<<endl; cout<<"sex: " <<sex<<endl<<endl; } }; int main() { Student stud1,stud2; stud1.set_data(1,"He",'f'); stud2.set_data(2,"She",'m'); stud1.display(); stud2.display(); return 0; }
类声明的第2种形式——更实用和常见
#include <iostream> #include <cstring> using namespace std; class Student { public: void set_data(int n, char *p,char s); void display( ); private: int num; char name[20]; char sex; }; void Student::set_data(int n, char *p,char s) { num=n; strcpy(name,p); sex=s; } void Student::display( ) { cout<<"num: "<<num<<endl; cout<<"name: " <<name<<endl; cout<<"sex: " <<sex<<endl<<endl; } int main() { Student stud1,stud2; stud1.set_data(1,"He",'f'); //stud1.sex='m'; //strcpy(stud1.name,"You"); stud2.set_data(2,"She",'m'); stud1.display(); stud2.display(); return 0; }
并非所有成员函数必须公有
#include <iostream> using namespace std; class Time { public: void set_time( ); void show_time( ); private: bool is_time(int, int, int); int hour; int minute; int sec; }; void Time::set_time( ) { char c1,c2; cout<<"请输入时间(格式hh:mm:ss)"; while(1) { cin>>hour>>c1>>minute>>c2>>sec; if(c1!=':'||c2!=':') cout<<"格式不正确,请重新输入"<<endl; else if (!is_time(hour,minute,sec)) cout<<"时间非法,请重新输入"<<endl; else break; } } void Time::show_time( ) { cout<<hour<<":"<<minute<<":"<<sec<<endl; } bool Time::is_time(int h,int m, int s) { if (h<0 ||h>24 || m<0 ||m>60 || s<0 ||s>60) return false; return true; } int main( ) { Time t1; t1.set_time( ); t1.show_time( ); return 0; }