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单选题 What will be displayed by the following program?#include <iostream>using namespace std;class CC {public: virtual string toString( ) { return "C"; }};class BB: public CC { string toString( ) { return "B"; }};class AA: public BB { virtual string toString( ) { return "A"; }};void displayObject(CC p) { cout << p.toString( );}int main( ) { AA a; BB b; CC c; displayObject(a); displayObject(b); displayObject(c); return 0;}
学科：C++语言程序设计
时间：2025-12-18 02:35:52
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题目1单选题
What is the correct signature for the overloaded subscript operator [ ] in class RA. long R::operator[ ](const int index)B. long &operator[ ](const int index)C. &long operator[ ](const int index)D. long operator&[ ](const int index)
题目2单选题
The output result after executing the following program is ( )#include <iostream>using namespace std;class complex {private: double re, im;public: complex (double r, double i) : re(r), im(i) { } double real ( ) const { return re; } double image ( ) const { return im; } complex &operator += (complex a) { re += a.re; im += a.im; return *this; }};void disp(const complex &z) { cout << "(" << z.real( ) << ", " << z.image( ) << ")";}int main ( ) { complex x(1, -2), y(2, 3); disp(x+=y); return 0;}A. (1, -2)B. (2, 3)C. (3, 5)D. (3, 1)
题目3单选题
The result of running the following program is ( ).#include <iostream>using namespace std;template <class T>class Num {private: T x;public: Num( ) { } Num(T x) { this->x = x; } Num<T>& operator + (const Num<T>& x2) { static Num<T> temp; temp.x = x + x2.x; return temp; } void disp( ) { cout << "x = " << x; }};int main ( ) { Num<int> A(3.8), B(4.8); A = A + B; A.disp( ); return 0;}A. x = 7B. x = 8C. x = 3D. x = 4
题目4单选题
Suppose r is an object with class type R, in order to perform 4 + r, the R class header file must containA. int operator( )B. R(int n)C. friend R operator+(int r1, const R& r2)D. R operator+(const R& r1)E. friend R operator+(const R& r2, int r1)
题目5单选题
In the expression x + y * z, operator + is overloaded using a member function, and * is overloaded using a non-member function. Then, which of the following is correctA. functions operator+( ) and operator*( ) contain two parametersB. functions operator+( ) and operator*( ) contain two and one parameters, respectivelyC. functions operator+( ) and operator*( ) contain one and two parameters, respectivelyD. functions operator+( ) and operator*( ) contain one parameter
题目6单选题
The followings are prototypes of a binary operator function overloaded as a non-member function except for ( )A. Fraction operator+ (Fraction, Fraction)B. Fraction operator- ( )C. Fraction& operator= (Fraction&, Fraction)D. Fraction& operator+= (Fraction&, Fraction)
题目7单选题
To convert a fundamental type to a class type, we need to create a ( )A. default constructorB. parameter constructorC. a copy constructorD. none of the above
题目8单选题
To convert a class type into a fundamental type, we need a ( )A. default constructorB. parameter constructorC. a copy constructorD. conversion operator
题目9单选题
Analyze the following program:#include <iostream>using namespace std;class AA {public: AA( ) { t( ); cout << "i from AA is " << i << endl; } void t( ) { setI(20); } virtual void setI(int i) { this->i = 2*i; } int i;};class BB: public AA {public: virtual void setI(int i) { this->i = 3*i; }};int main( ) { AA *p = new BB( ); return 0;}A. The constructor of class AA is not calledB. The constructor of class AA is called and it displays "i from AA is 0"C. The constructor of class AA is called and it displays "i from AA is 40"D. The constructor of class AA is called and it displays "i from AA is 60"
题目10单选题
What will be displayed by the following program?#include <iostream>using namespace std;class CC {public: virtual string toString( ) { return "C"; }};class BB: public CC { string toString( ) { return "B"; }};class AA: public BB { virtual string toString( ) { return "A"; }};void displayObject(CC p) { cout << p.toString( );}int main( ) { AA a; BB b; CC c; displayObject(a); displayObject(b); displayObject(c); return 0;}A. ABCB. CBAC. AAAD. BBBE. CCC
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