如下函数的作用是以双倍行距输出文件：void　double_space(ifstream&　f,ofstream&　t){char　c;while　(__________){____________;if(c=='n')　t.out(c);}}画线处缺失的部分是

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• 1下列是重载惩罚运算符的函数原型生命，其中错误的是

  A.MyClass　operator　*(double,double);

  B.MyClass　operator　*　(double,MyClass);

  C.MyClass　operator　*　(MyClass,double);

  D.MyClass　operator　*　(MyClass,MyClass);

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• 2有如下程序：#include　<iostream>using　namespace　std;class　Base{public:void　output(){cout<<1;}virtual　void　Print(){cout<<'B';}};class　derived:public　Base{public:void　output(){cout<<2;}void　Print(){cout<<'D';}};int　main(){Base　*ptr=new　Derived;ptr->output();ptr->Print();delete　ptr;return　0;}程序的输出结果是

  A.1B

  B.1D

  C.2B

  D.2D

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• 3若有如下类定义class　B{void　fun1(){}protected:double　var1;public:void　fun2(){}};class　D:public　B{protected:void　fun3(){}};已知obj是类D的对象，下列语句中不违反类成员访问控制权限的是

  A.obj.fun1();

  B.obj.var1;

  C.obj.fun2();

  D.obj.fun3();

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• 4有如下程序：#include　<iostream>using　namespace　std;class　Base{public:Base(int　x=0){cout<<x;}};class　Derived:public　Base{public:Derived(int　x=0){cout<<x;}private:Base　val;};int　main(){Derived　d(1);return　0;}程序的输出结果是

  A.0

  B.1

  C.01

  D.001

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• 5有如下程序：#include　<iostream>using　namespace　std;class　Part{public:Part(int　x=0):val(x){cout<<val;}~Part(){cout<<val;}private:int　val;};class　Whole{public:Whole(int　x,int　y,　int　z=0):p2(x),p1(y),val(z){cout<<val;}~Whole(){cout<<val;}private:Part　p1,p2;int　val;};int　main(){Whole　obj(1,2,3);return　0;}程序的输出结果是

  A.123321

  B.213312

  C.213

  D.123123

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• 6有如下程序：#include　<iostream>using　namespace　std;class　B{public:virtual　void　show(){cout<<"B";}};class　D:public　B{public:void　show(){cout<<"D";}};void　fun1(B　*ptr){ptr->show();}void　fun2(B　&amp;ref){ref.show();}void　fun3(B　b){b.show();}int　main(){B　b,*p=new　D;D　d;fun1(p);fun2(b);fun3(d);return　0;}程序的输出结果是

  A.BBB

  B.BBD

  C.DBB

  D.DBD

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