指向数组的指针作为函数参数

I wrote a function which takes a pointer to an array to initialize its values:

我写了一个函数，它接受一个指向数组的指针来初始化它的值：

#define FIXED_SIZE 256
int Foo(int *pArray[FIXED_SIZE])
{
/*...*/
}

//Call:

int array[FIXED_SIZE];
Foo(&array);

And it doesn't compile:

它不编译：

error C2664: 'Foo' : cannot convert parameter 1 from 'int (*__w64 )[256]' to 'int *[]'

错误C2664：'Foo'：无法将参数1从'int（* __ w64）[256]'转换为'int * []'

However, I hacked this together:

但是，我一起攻击了这个：

typedef int FixedArray[FIXED_SIZE];
int Foo(FixedArray *pArray)
{
/*...*/
}

//Call:

FixedArray array;
Foo(&array);

And it works. What am I missing in the first definition? I thought the two would be equivalent...

它有效。我在第一个定义中缺少什么？我以为这两个是等价的......

3 个解决方案

#1

int Foo(int *pArray[FIXED_SIZE])
{
/*...*/
}

In the first case, pArray is an array of pointers, not a pointer to an array.

在第一种情况下，pArray是一个指针数组，而不是指向数组的指针。

You need parentheses to use a pointer to an array:

您需要括号来使用指向数组的指针：

int Foo(int (*pArray)[FIXED_SIZE])

You get this for free with the typedef (since it's already a type, the * has a different meaning). Put differently, the typedef sort of comes with its own parentheses.

你可以使用typedef免费获得这个（因为它已经是一个类型，*具有不同的含义）。换句话说，typedef类型带有自己的括号。

Note: experience shows that in 99% of the cases where someone uses a pointer to an array, they could and should actually just use a pointer to the first element.

注意：经验表明，在99％的情况下，有人使用指向数组的指针，他们可以而且实际上应该只使用指向第一个元素的指针。

#2

One simple thing is to remember the clockwise-spiral rule which can be found at http://c-faq.com/decl/spiral.anderson.html

一个简单的事情是记住顺时针螺旋规则，可以在http://c-faq.com/decl/spiral.anderson.html找到。

That would evaluate the first one to be an array of pointers . The second is pointer to array of fixed size.

那将评估第一个是一个指针数组。第二个是指向固定大小数组的指针。

#3

An array decays to a pointer. So, it works in the second case. While in the first case, the function parameter is an array of pointers but not a pointer to integer pointing to the first element in the sequence.

数组衰减到指针。所以，它适用于第二种情况。在第一种情况下，函数参数是一个指针数组，但不是一个指向序列中第一个元素的整数的指针。

#1

int Foo(int *pArray[FIXED_SIZE])
{
/*...*/
}