Diamond problem occurs when we use multiple inheritance in programming languages like C++ or Java.

当我们在诸如C ++或Java的编程语言中使用多重继承时，就会出现钻石问题。

Let’s understand this with one example.

让我们用一个例子来理解这一点。

继承中的钻石问题 (Diamond Problem in Inheritance)

class A {	void display()	{		//some code	}} class B : public A{	void display()	{		//some code	}} class C : public A{	void display()	{		//some code	}} class D : public B, public C{	//contains two display() functions}

Suppose there are four classes A, B, C and D. Class B and C inherit class A. Now class B and C contains one copy of all the functions and data members of class A.

假设有四个类A，B，C和D。类B和C继承了类A。现在，类B和C包含类A的所有函数和数据成员的一个副本。

Class D is derived from Class B and C. Now class D contains two copies of all the functions and data members of class A. One copy comes from class B and another copy comes from class C.

D类是从B和C派生的。现在D类包含A类所有函数和数据成员的两个副本。一个副本来自B类，另一个副本来自C类。

Let’s say class A have a function with name display(). So class D have two display() functions as I have explained above. If we call display() function using class D object then ambiguity occurs because compiler gets confused that whether it should call display() that came from class B or from class C. If you will compile above program then it will show error.

假设类A有一个名为display()的函数。 因此，类D具有两个我上面已经解释过的display()函数。 如果我们使用类D对象调用display()函数，则会产生歧义，因为编译器会混淆应调用来自类B还是来自类C的display()。如果您要编译上述程序，则会显示错误。

This kind of problem is called diamond problem as a diamond structure is formed (see the image).

这种问题被称为钻石问题，因为形成了钻石结构(见图)。

如何清除C ++中的Diamond问题？ (How to Remove Diamond Problem in C++?)

We can remove diamond problem by using virtual keyword. It can be done in following way.

我们可以使用虚拟关键字消除钻石问题。 可以通过以下方式完成。

class A {	void display()	{		//some code	}} class B : virtual public A{	void display()	{		//some code	}} class C : virtual public A{	void display()	{		//some code	}} class D : public B, public C{	//contains one display() functions}

You can see we have marked class B and C as virtual. Now compiler takes care that only one copy of data members and functions of class A comes to class D.

您可以看到我们已将B类和C类标记为虚拟。 现在，编译器要注意的是，类D的数据成员和函数只有一个副本。

如何清除Java中的钻石问题？ (How to Remove Diamond Problem in Java?)

To remove this problem . Although we can achieve multiple inheritance using interfaces.

为了消除此问题， 。 尽管我们可以使用接口实现多重继承。

Comment below if you found anything missing or incorrect in above diamond problem tutorial.

如果您在上述钻石问题教程中发现任何缺失或不正确的地方，请在下面评论。

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