c构造函数和析构函数

Program 1:

程序1：

#include
    
     using namespace std;class Sample{	private:		int X;		int Y;				public:		Sample(int x, int y)		{			X = x;			Y = y;		}			void set(int x, int y)		{			X = x;			Y = y;		}				void print()		{			cout<
     
      <<" "<
      
       <
      
     
    

Output:

输出：

main.cpp: In function ‘int main()’:main.cpp:32:12: error: no matching function for call to ‘Sample::Sample()’  Sample S[2];

Explanation:

说明：

The above code will generate a syntax error because in the we created an that must be instantiated by the , but in the class, the default constructor is not defined.

上面的代码将产生语法错误，因为在我们创建了必须由实例化 ，但是在类中，未定义默认构造函数。

Program 2:

程式2：

#include 
    
     using namespace std;class Sample {private:    int X;    int Y;public:    Sample(int x, int y)    {        X = x;        Y = y;    }    void set(int x, int y)    {        X = x;        Y = y;    }    void print()    {        cout << X << " " << Y << endl;    }};int main(){    Sample S[2] = { Sample(0, 0), Sample(0, 0) };    Sample* PTR;    PTR = S;    PTR[0].set(10, 20);    PTR[1].set(30, 40);    PTR[0].print();    PTR[1].print();    return 0;}
    

Output:

输出：

10 2030 40

Explanation:

说明：

In the above program, we created a class Sample that contains two X and Y, one , set() and print() member functions. 

在上面的程序中，我们创建了一个Sample类，其中包含两个 X和Y ，一个 ， set()和print()成员函数。

Now coming to the main() function, we created an array of objects and that will instantiated by the parameterized constructor. And created a pointer that is being initialized with the base address of array objects. And then called set() and print() functions using the pointer.

现在进入main()函数，我们创建了一个对象数组，该数组将由参数化构造函数实例化。 并创建了一个使用数组对象的基地址初始化的指针。 然后使用指针调用set()和print()函数。

Program 3:

程式3：

#include 
    
     using namespace std;class Sample {private:    int X;public:    Sample() const    {    }    void set(int x)    {        X = x;    }    void print()    {        cout << X << endl;    }};int main(){    Sample S;    S.set(10);    S.print();    return 0;}
    

Output:

输出：

main.cpp:9:14: error: constructors may not be cv-qualified     Sample() const              ^~~~~

Explanation:

说明：

The above program will generate an error because we cannot as a const member function in C++.

上面的程序将产生错误，因为我们不能在C ++中将函数为const成员函数。

翻译自:

c构造函数和析构函数