写出下面程序的运行结果。
#include<iostream>
using namespace std;
class example
{
public:
example(int n)
{
i=n;
cout<<"Constructing\n";
}
~example()
{
cout <<"Destructing\n";
}
int get_i()
{
return i;
}
private:
int i;
};
int sqr_it(example o)
{
return o.get_i()* o.get_i();
}
int main()
{
example x(10);
cout<<x.get_i()<<endl;
cout<<sqr_it(x)<<endl;
return 0;
}
Constructing
10
100
Destructing
Destructing
#include<iostream>
using namespace std;
class aClass
{
public:
aClass()
{
total++;}
~aClass()
{
total--;}
int gettotal()
{
return total;}
private:
static int total;
};
int aClass::total=0;
int main()
{
aClass o1,o2,o3;
cout<<o1.gettotal()<<" objects in existence\n";
aClass *p;
p=new aClass;
if (!p)
{
cout<<"Allocation error\n";
return 1;
}
cout<<o1.gettotal();
cout<<" objects in existence after allocation\n";
delete p;
cout<<o1.gettotal();
cout<<" objects in existence after deletion\n";
return 0;
}
3 objects in existence
4 objects in existence after allocation
3 objects in existence after deletion
#include<iostream>
using namespace std;
class test
{
public:
test() ;
~test(){
};
private:
int i; };
test::test()
{
i = 25;
cout<<"Here＇s the program output. \n";
cout<<"Let′s generate some stuff...\n";
for (int ctr=0; ctr<10; ctr++)
{
cout<<"Counting at "<<ctr<<"\n";
}
}
test anObject;
int main()
{
return 0;
}
Here＇s the program output.
Let′s generate some stuff…
Counting at 0
Counting at 1
Counting at 2
Counting at 3
Counting at 4
Counting at 5
Counting at 6
Counting at 7
Counting at 8
Counting at 9
#include<iostream>
using namespace std;
class R{
public:
R(int r1,int r2)
{
R1=r1;
R2=r2;
}
void print();
void print() const;
private:
int R1,R2;
};
void R::print()
{
cout<<R1<<","<<R2<<endl;
}
void R::print() const
{
cout<<R1<<","<<R2<<endl;
}
int main()
{
R a(6,8);
const R b(56,88);
b.print();
return 0;
}
56,88
#include<iostream>
using namespace std;
class Sample{
public:
Sample( int i,int j)
{
x=i;
y=j;
}
void disp()
{
cout<<"disp1"<<endl;
}
void disp() const
{
cout<<"disp2"<<endl;
}
private:
int x,y;
};
int main()
{
const Sample a(1,2);
a.disp();
return 0;
}
disp2
#include<iostream>
using namespace std;
class A{
public:
void set(int i,int j)
{
x=i;
y=j;
}
int get_y()
{
return y;
}
private:
int x,y;
};
class box{
private:
int length,width;
A label;
public:
void set(int l,int w,int s,int p)
{
length=l;
width=w;
label.set(s,p);
}
int get_area()
{
return length*width;
}
};
int main()
{
box b;
b.set(4,6,1,20);
cout<<b.get_area()<<endl;
return 0;
}
24
#include<iostream>
using namespace std;
class B {
public:
B(){
}
B(int i,int j)
{
x=i;
y=j;
}
void printb()
{
cout<<x<<","<<y<<endl;
}
private:
int x,y;
};
class A{
public:
A()
{
}
A(int i,int j);
void printa();
private:
B c;
};
A::A(int i,int j):c(i,j)
{
}
void A::printa()
{
c.printb();
}
int main()
{
A a(7,8);
a.printa();
return 0;
}
7,8
#include <iostream>
using namespace std;
class B1{
public:
B1(int i)
{
b1=i;cout<<"Constructor B1. "<<endl; }
void Print()
{
cout<<b1<<endl;}
private:
int b1;
};
class B2 {
public:
B2 (int i)
{
b2=i; cout<<"Constructor B2. "<<endl;}
void Print()
{
cout<<b2<<endl;}
private:
int b2;
};
class A: public B2, public B1
{
public:
A(int i,int j,int l);
void Print();
private:
int a;
};
A::A(int i,int j,int l):B1(i), B2(j)
{
a=l; cout<<"Constructor A. "<<endl;}
void A:: Print()
{
B1:: Print();
B2:: Print();
cout<<a<<endl;
}
int main()
{
A aa(3,2,1);
aa. Print();
return 0;
}
Constructor B2.
Constructor B1.
Constructor A.
3
2
1
#include<iostream>
using namespace std;
class A{
private:
int a;
public:
A()
{
a=0;}
A(int i)
{
a=1;}
void Print()
{
cout<<a<<",";}
};
class B: public A
{
private:
int b1, b2;
public:
B()
{
b1=0;b2=0;}
B(int i)
{
b1=i;b2=0;}
B(int i, int j,int k): A(i), b1(j),b2(k)
{
}
void Print()
{
A:: Print();
cout<<b1<<","<<b2<<endl;
}
};
int main()
{
B ob1,ob2(1),ob3(3,6,9);
ob1.Print();
ob2.Print();
ob3.Print();
return 0;
}
0,0,0
0,1,0
1,6,9
#include <iostream>
using namespace std;
class shapes {
protected:
int x, y;
public:
void setvalue(int d, int w = 0) {
x = d;
y = w;
}
virtual void disp() = 0;
};
class square: public shapes {
public:
void disp() {
cout << x *y << endl;
}
};
int main() {
shapes *ptr;
square s1;
ptr = &s1;
ptr->setvalue(10, 5);
ptr->disp();
return 0;
}
50
#include <iostream>
using namespace std;
class Stock {
public:
virtual void print() {
cout << "Stock class.\n";
}
};
class Der1_Stock: public Stock {
public:
void print() {
cout << "Der1_Stock class.\n";
}
};
class Der2_Stock: public Stock {
public:
void print() {
cout << "Der2_Stock class.\n";
}
};
int main() {
Stock s1;
Stock *ptr;
Der1_Stock d1;
Der2_Stock d2;
ptr = &s1;
ptr->print();
ptr = &d1;
ptr->print();
ptr = &d2;
ptr->print();
return 0;
};
Stock class.
Der1_Stock class.
Der2_Stock class
#include <iostream>
using namespace std ;
class Array{
public :
Array(int);
int& operator ()(int); //重载运算符()
private :
int *m ;
int x ;
} ;
Array :: Array(int x)
{
this->x=x ;
m=new int[x] ;
for(int i=0;i<x;i++)
*(m+i)=i;
}
int& Array :: operator() (int x1)
{
return(*(m+x1)) ; }
int main ()
{
Array a(10) ;
cout<<a(5) ;
a(5) =7 ;
cout<<a(5) ;
return 0 ;
}
57
#include <iostream>
using namespace std;
class A {
public :
A(int i) : x(i)
{
}
A ()
{
x = 0 ;
}
friend A operator++(A a) ;
friend A operator--(A &a) ;
void print () ;
private :
int x ;
} ;
A operator++(A a)
{
++a.x;
return a ;
}
A operator--(A &a)
{
--a.x ;
return a;
}
void A::print()
{
cout << x << endl;
}
int main()
{
A a(7) ;
++a;
a.print() ;
--a ;
a.print() ;
return 0 ;
}
7
6