无论是java还是c++都提供了三种访问控制权限:
public、private、protected
它们提供类级别的访问控制,但是类的成员函数可以访问同一类的所有对象的所有私有成员,例如下面的C++示例:
#include "stdafx.h"#include <stdlib.h>class test{protected:private:int ivalue;int _get_and_add(){return (ivalue + 10);}public:test(){ivalue = 0;}void setValue(int _ivalue){ivalue = _ivalue;}void setValue(test t){ivalue = t.ivalue;}void add(test t){ivalue += t._get_and_add();}int getValue(){return ivalue;}};int _tmain(int argc, _TCHAR* argv[]){test t1,t2;printf("1. value:\n");printf(" t1: %d \n",t1.getValue());printf(" t2: %d \n",t2.getValue());t2.setValue(100);t1.setValue(t2);printf("2.after setValue:\n");printf(" t1: %d \n",t1.getValue());printf(" t2: %d \n",t2.getValue());t1.add(t2);printf("3.after add_other:\n");printf(" t1: %d \n",t1.getValue());printf(" t2: %d \n",t2.getValue());system("pause");return 0;}
其中类test的成员函数:
void setValue(test t){ivalue = t.ivalue;}
void add(test t){ivalue += t._get_and_add();}
分别访问了同类的其他对象(由参数传递过来)t 的私有数据成员 ivalue以及私有函数,上述程序的输出结果为: