Java引用和C ++引用之间的区别是什么 [英] What's the difference between a Java reference and C++ reference

问题描述

所以我一直在想（在阅读这个Java pdf）...

我知道这可能看起来很蠢，但为什么我不能这样做在c + 。

  float& f = new float; 
  

这不是说f的引用是新float的地址？

在Java中，我看到了这样的东西。

  String s = new String ）
  

String s 参考。

Java中的'reference'一词是否与C ++中的含义相同？

解决方案

Java引用更接近于C ++ 指针，而不是C ++ 引用。在Java中，您可以使用引用执行以下操作：

• 更改其引用的对象


• 检查两个引用是否相等或不相等


• 向引用对象发送消息。

在C ++中，指针具有这些相同的属性。因此，您在C ++中寻找的代码类似于

  float * f = new float; 
  

这是完全合法的。为了更好的比较，这个Java代码：

  String myString = new String（This is a string！ //通常我不会在这里分配一个字符串，但只是为了并行结构。 
 System.out.println（myString.length（））; 
 
 / *重新指定myString以指向不同的字符串对象。 * / 
 myString = new String（这是另一个字符串！ 
 System.out.println（myString.length（））; 
  

会映射到此C ++代码：

  std :: string * myString = new std :: string（This is a string）; 
 std :: cout<< myString-> length（）<< std :: endl; 
 
 delete myString; // C ++中没有GC！ 
 
 / *重新指定myString以指向不同的字符串对象。 * / 
 myString = new std :: string（这是另一个字符串！ 
 std :: cout<< myString-> length（）<< std :: endl; 
 
 delete myString; // C ++中没有GC！ 
  

希望这有助于！

So I've been thinking (while reading this Java pdf)...

I know this may seem silly but why can't I do this in c++.

float &f = new float;

Isn't this saying the reference of f is the address of new float?

In Java, I see something like this

String s = new String("something")

String s is called a string reference.

Does the word 'reference' in Java have the same meaning as in C++?

解决方案

Java references are much closer to C++ pointers rather than C++ references. In Java, you can do the following with a reference:

• Change which object it refers to
• Check whether two references are equal or unequal
• Send messages to the referenced object.

In C++, pointers have these same properties. As a result, the code you're looking for in C++ is something like

float* f = new float;

Which is perfectly legal. For a better comparison, this Java code:

String myString = new String("This is a string!"); // Normally I wouldn't allocate a string here, but just for the parallel structure we will.
System.out.println(myString.length());

/* Reassign myString to point to a different string object. */
myString = new String("Here's another string!");
System.out.println(myString.length());

would map to this C++ code:

std::string* myString = new std::string("This is a string");
std::cout << myString->length() << std::endl;

delete myString; // No GC in C++!

/* Reassign myString to point to a different string object. */
myString = new std::string("Here's another string!");
std::cout << myString->length() << std::endl;

delete myString; // No GC in C++!

Hope this helps!

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