매개 변수에서 '&'를 함수에 배치 할 위치는 어디입니까?

Question

누구는 C++에서

void fun(MyClass &mc); 

및

void fun(MyClass& mc); 

의 차이점은 무엇인지 말씀해 주시겠습니까?

Answer 1

주어진대로. 원래

는 C 허용 것 :

int x, *y; 

는 둘 모두 int, x 및 포인터가 int로 y를 선언하려면.

따라서 유형 정의의 일부 (포인터가되는 비트)는 다른 부분과 분리 될 수 있습니다.

C++이 (가)이 도매가를 복사했습니다.

다음은 참조가 추가 된 곳이며 *이 아닌 &을 제외하고 유사한 선언 스타일을가집니다. 즉, MyClass &mc과 MyClass& mc이 허용되었습니다. 선택에

이 *에 관해서, Strousup wrote : 그것은 &에 올 때 확장으로

Both are "right" in the sense that both are valid C and C++ and both have exactly the same meaning. As far as the language definitions and the compilers are concerned we could just as well say "int*p;" or "int * p;"

The choice between "int* p;" and "int *p;" is not about right and wrong, but about style and emphasis. C emphasized expressions; declarations were often considered little more than a necessary evil. C++, on the other hand, has a heavy emphasis on types.

A "typical C programmer" writes "int *p;" and explains it "*p is what is the int" emphasizing syntax, and may point to the C (and C++) declaration grammar to argue for the correctness of the style. Indeed, the * binds to the name p in the grammar.

A "typical C++ programmer" writes "int* p;" and explains it "p is a pointer to an int" emphasizing type. Indeed the type of p is int*. I clearly prefer that emphasis and see it as important for using the more advanced parts of C++ well.

The critical confusion comes (only) when people try to declare several pointers with a single declaration:

int* p, p1; // probable error: p1 is not an int*

Placing the * closer to the name does not make this kind of error significantly less likely.

int *p, p1; // probable error?

Declaring one name per declaration minimizes the problem - in particular when we initialize the variables. People are far less likely to write:

int* p = &i; int p1 = p; // error: int initialized by int*

And if they do, the compiler will complain.

Whenever something can be done in two ways, someone will be confused. Whenever something is a matter of taste, discussions can drag on forever. Stick to one pointer per declaration and always initialize variables and the source of confusion disappears. See The Design and Evolution of C++ for a longer discussion of the C declaration syntax.

는 MyClass& mc는 "전형적인 C++"스타일과 일치합니다.

Answer 2

컴파일러에는 아무런 차이가 없습니다.

첫 번째는 일반적인 C- 구문에 더 가깝고, 후자는 C + + - ish입니다.