不可在 for 循环体内修改循环变量，防止 for 循环失去控制
不可在 for 循环体内修改循环变量，防止 for 循环失去控制。
1 #include <iostream> 2 3 /* run this program using the console pauser or add your own getch, system("pause") or input loop */ 4 using namespace std; 5 //基类 6 class First { 7 int val1; 8 protected: 9 void SetVal1(int v) { 10 val1=v; 11 } 12 public: 13 show_First(void) { 14 cout<<"val1="<<val1<<endl; 15 } 16 }; 17 //派生类 18 class Second:public First { 19 int val2; 20 protected: 21 void SetVal2(int v) { 22 SetVal1(v); //使用First 基类的保护成员 23 val2=v; 24 } 25 public: 26 show_Second(void) { 27 show_First(); 28 cout<<"val2="<<val2<<endl; 29 } 30 }; 31 //派生类 32 class Third:public Second { 33 int val3; 34 public: 35 void SetVal3(int n) { 36 SetVal1(n); //使用First 基类的保护成员 37 SetVal2(n); //使用Second基类的保护成员 38 val3=n; 39 } 40 show_Third(void) { 41 show_Second(); 42 cout<<"val3="<<val3<<endl; 43 } 44 }; 45 //main()函数的定义 46 47 int main(int argc, char** argv) { 48 First f1; 49 //f1.SetVal1(1); 不可访问 50 51 Second s1; 52 //s1.SetVal1(1); 不可访问 53 //s1.SetVal2(2); 不可访问 54 55 Third t1; 56 //t1.SetVal1(1); 不可访问 57 //t1.SetVal2(2); 不可访问 58 t1.SetVal3(10); 59 60 //显示t1对象的数据 61 cout<<"t1.show_Third();"<<endl; 62 t1.show_Third(); 63 cout<<"t1.show_Second();"<<endl; 64 t1.show_Second(); 65 cout<<"t1.show_First();"<<endl; 66 t1.show_First(); 67 return 0; 68 }
