C++ 通过引用传递数组
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Passing an array by reference
提问by John DB
How does passing a statically allocated array by reference work?
通过引用传递静态分配的数组如何工作?
void foo(int (&myArray)[100])
{
}
int main()
{
int a[100];
foo(a);
}
Does (&myArray)[100]
have any meaning or its just a syntax to pass any array by reference?
I don't understand separate parenthesis followed by big brackets here. Thanks.
是否(&myArray)[100]
有任何意义或它只是一个语法按引用传递任何阵列?我不明白单独的括号后面是大括号。谢谢。
回答by Erik
It's a syntax for array references - you need to use (&array)
to clarify to the compiler that you want a reference to an array, rather than the (invalid) array of references int & array[100];
.
这是数组引用的语法 - 您需要使用(&array)
来向编译器说明您想要对数组的引用,而不是(无效的)引用数组int & array[100];
。
EDIT: Some clarification.
编辑:一些澄清。
void foo(int * x);
void foo(int x[100]);
void foo(int x[]);
These three are different ways of declaring the same function. They're all treated as taking an int *
parameter, you can pass any size array to them.
这三种是声明相同函数的不同方式。它们都被视为接受一个int *
参数,您可以将任何大小的数组传递给它们。
void foo(int (&x)[100]);
This only accepts arrays of 100 integers. You can safely use sizeof
on x
这仅接受 100 个整数的数组。您可以放心地使用sizeof
上x
void foo(int & x[100]); // error
This is parsed as an "array of references" - which isn't legal.
这被解析为“引用数组”——这是不合法的。
回答by Martin York
It's just the required syntax:
这只是所需的语法:
void Func(int (&myArray)[100])
^ Pass array of 100 int
by reference the parameters name is myArray
;
^int
通过引用传递 100 个数组,参数名称为myArray
;
void Func(int* myArray)
^ Pass an array. Array decays to a pointer. Thus you lose size information.
^ 传递一个数组。数组衰减为指针。因此,您会丢失尺寸信息。
void Func(int (*myFunc)(double))
^ Pass a function pointer. The function returns an int
and takes a double
. The parameter name is myFunc
.
^ 传递函数指针。该函数返回一个int
并接受一个double
。参数名称是myFunc
.
回答by cpx
It is a syntax. In the function arguments int (&myArray)[100]
parenthesis that enclose the &myArray
are necessary. if you don't use them, you will be passing an array of references
and that is because the subscript operator []
has higher precedence over the & operator
.
它是一种语法。在函数参数int (&myArray)[100]
中,括号&myArray
是必要的。如果你不使用它们,你会传递一个array of references
,就是因为subscript operator []
拥有更高的优先级& operator
。
E.g. int &myArray[100] // array of references
例如 int &myArray[100] // array of references
So, by using type construction ()
you tell the compiler that you want a reference to an array of 100 integers.
因此,通过使用,type construction ()
您可以告诉编译器您想要一个包含 100 个整数的数组的引用。
E.g int (&myArray)[100] // reference of an array of 100 ints
例如 int (&myArray)[100] // reference of an array of 100 ints
回答by Eduardo A. Fernández Díaz
Arrays are default passed by pointers. You can try modifying an array inside a function call for better understanding.
数组默认通过指针传递。您可以尝试在函数调用中修改数组以更好地理解。