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?
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++?
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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