什么是int&意思 [英] What does int & mean

问题描述

一个C ++问题，

我知道

  int * foo（void）
  

foo将返回指向int类型的指针

如何

  int& foo（void）
  
 
 
 
它是什么？
 
 
 
非常感谢！
解决方案
它返回一个引用到一个int。引用类似于指针，但有一些重要的区别。我建议您阅读指针，引用，对象和原始数据类型之间的差异。
 
 
 
有效的C ++和更有效的C ++ Meyers）有一些很好的描述差异和何时使用指针vs引用。
 
 
 
编辑：有很多答案说，语法糖以更容易处理指针。 
 
 
 
请考虑以下代码：
  int a = 3; 
 int b = 4; 
 int * pointerToA =& a; 
 int * pointerToB =& b; 
 int * p = pointerToA; 
 p = pointerToB; 
 printf（％d％d％d \\\
，a，b，* p）; // Prints 3 4 4 
 int& referenceToA = a; 
 int& referenceToB = b; 
 int& r = referenceToA; 
 r = referenceToB; 
 printf（％d％d％d \\\
，a，b，r）; // Prints 4 4 4 
  
行 p = pointerToB 更改 p 的值，即它现在指向不同的内存块。 
 
 
 
  r = referenceToB 完全不同：它分配 b 到 a 的值。它不更改 r 。  r 仍然是对同一块内存的引用。
 
 
 
区别是微妙但非常重要。 p> 
 
 
如果你仍然认为引用只是用于指针处理的语法糖，请阅读Scott Meyers的书。他可以比我更好地解释差异。
 
A C++ question,

I know 
int* foo(void)
foo will return a pointer to int type

how about 
int &foo(void)
what does it return?

Thank a lot!
解决方案
It returns a reference to an int. References are similar to pointers but with some important distinctions. I'd recommend you read up on the differences between pointers, references, objects and primitive data types.

"Effective C++" and "More Effective C++" (both by Scott Meyers) have some good descriptions of the differences and when to use pointers vs references.

EDIT: There are a number of answers saying things along the lines of "references are just syntactic sugar for easier handling of pointers". They most certainly are not.

Consider the following code:
int a = 3;
int b = 4;
int* pointerToA = &a;
int* pointerToB = &b;
int* p = pointerToA;
p = pointerToB;
printf("%d %d %d\n", a, b, *p); // Prints 3 4 4
int& referenceToA = a;
int& referenceToB = b;
int& r = referenceToA;
r = referenceToB;
printf("%d %d %d\n", a, b, r); // Prints 4 4 4
The line p = pointerToB changes the value of p, i.e. it now points to a different piece of memory. 

r = referenceToB does something completely different: it assigns the value of b to where the value of a used to be. It does not change r at all. r is still a reference to the same piece of memory.

The difference is subtle but very important.

If you still think that references are just syntactic sugar for pointer handling then please read Scott Meyers' books. He can explain the difference much better than I can.

                        
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