Java 参考和 C++ 参考有什么区别 [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 时)...

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

我知道这可能看起来很傻，但为什么我不能在 C++ 中做到这一点.

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

float &f = new float;

这不是说f的引用是new float的地址吗?

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

在 Java 中，我看到类似这样的东西

In Java, I see something like this

String s = new String("something")

String s 称为字符串引用.

Java 中的引用"一词与 C++ 中的含义相同吗?

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

推荐答案

Java 引用更接近 C++ 指针，而不是 C++ 引用.在 Java 中，您可以通过引用执行以下操作:

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

• 更改它引用的对象
• 检查两个引用是否相等或不相等
• 向引用的对象发送消息.

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

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;

这是完全合法的.为了更好的比较，这段 Java 代码:

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());

将映射到此 C++ 代码:

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++!

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