有以下程序include using namespace std; class sample { private: int x; public:

有以下程序 #include ＜iostream＞ using namespace std; class sample { private: int x; public: sample(int a) { x=a; } friend double square(sample s); }; double square(sample s) { return s.x*s.x; } int main() { sample s1 (20),s2(30); cout＜＜square(s2)＜＜end1; return 0; } 执行结果是

A．20

B．30

C．900

D．400

[单选题]有以下程序 include using namespace std; class MyClass { public:有以下程序 #include＜iostream＞ using namespace std； class MyClass { public： MyClass(intn) {number＝n；} //拷贝构造函数 MyClass (MyClass& other) {number＝other.number；} ～MyClass(){} private： int number； }

[主观题]有以下程序: include using namespace std; class MyClass { public: static int s; M有以下程序：include＜iostream＞using namespace std;class MyClass{public:static int s;MyClass();void SetValue(int val);};int MyClass::s=0;MyClass::MyClass(){S++;}void MyClass::SetValue

[单选题]若有以下程序:include using namespace std;class Base {public:Base() { x=0; } int若有以下程序： #include ＜iostream＞ using namespace std; class Base { public: Base() { x=0; } int x; }; class Derivedl: virtual public Base { public: Derivedl() { x=10; } }; class Deriv

[单选题]若有以下程序:include using namespace std;class A{private: int a;public: A(int i若有以下程序： #include ＜iostream＞ using namespace std; class A { private: int a; public: A(int i) { a=i; } void disp() { cout＜＜a＜＜", "; } }; class B { private: int b; public: B(int

[单选题]若有以下程序:include using namespace std;class Base{public:Base (){x=0;}int x;}若有以下程序： #include ＜iostream＞ using namespace std; class Base { public: Base () { x=0; } int x; }; class Derived1 : virtual public Base { public: Derived1 () { x=10; } }; class De

[单选题]若有以下程序:include using namespace std;class A{private:int a;public:A(int i){若有以下程序： #include ＜iostream＞ using namespace std; class A { private: int a; public: A(int i) { a=i; } void disp () { cout＜＜a＜＜","; } }; class B { private: int b; public: B(int

[单选题]若有以下程序:include using namespace std;class A{public:A() { }A(int i){x1=i;}v若有以下程序： #include ＜iostream＞ using namespace std; class A { public: A() { } A(int i) { x1=i; } void dispa0 { cout＜＜"x1="＜＜x1＜＜","; } private: int x1; }; class B: public A { p

[单选题]若有以下程序:include using namespace std;class A{protected: int a;public: A() {若有以下程序： #include ＜iostream＞ using namespace std; class A { protected: int a; public: A() { a=10; } }; class A1 : public A { public: A1() { a=a+1; } }; class A2 : public A { publ

[单选题]若有以下程序:include using namespace std;class data{public: int x; data (int x)若有以下程序： #include ＜iostream＞ using namespace std; class data { public: int x; data (int x) { data: :x=x; } }; class A { private: data d1; public: A(int x) : d1 (x) { } void dispa

[单选题]若有以下程序:include using namespace std;class A{private: int x;protected: int若有以下程序： #include ＜iostream＞ using namespace std; class A { private: int x; protected: int y; public: int z; void setx(int i) { x=i; } int getx () { return x; }; class B : protect