从C到D的数组指针。

I'm using D and interfacing with some C libraries. As a result I have to convert D arrays to pointers for C (ex. short*). Currently I just cast them like this:

我使用D，并与一些C库交互。因此，我必须将D数组转换为C (ex. short*)的指针。现在我就这样把它们扔了:

int[] dArray = [0, 1, 2, 3, 4];
myCFunction(cast(int*) dArray);

Is this unsafe? I tried to do:

这是不安全的吗?我想做的事:

myCFunction(&dArray);

But doing that gives the function an int[]* instead of int*. I see that in C++ some people take the first element like this:

但是这样做给了函数一个int[]*而不是int*。我在c++中看到一些人使用第一个元素:

myCFunction(&dArray[0]);

But wouldn't that pointer only point to the first element? I am new to pointers and references as I have come from the world of Java.

但是那个指针不是指向第一个元素吗?我是来自Java世界的新指针和引用。

How would I convert an array to a pointer so I can pass it to a C function?

我如何将数组转换为一个指针，这样我就可以把它传递给C函数?

1 个解决方案

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In D, an array is actually (conceptually) this:

在D中，数组实际上(概念上)是这样的:

struct {
    size_t length;
    void* ptr;
};

The usual way of getting a pointer from an array is to use the .ptr field. In your case: myCFunction(dArray.ptr);

从数组中获取指针的通常方法是使用.ptr字段。在你的例子:myCFunction(dArray.ptr);

But wouldn't that pointer only point to the first element

但是这个指针不会指向第一个元素。

Because the elements are stored contiguously in memory, a pointer to the first element is all we need. We just add an offset to that pointer if we want to get the addresses of other elements.

因为元素是在内存中连续存储的，所以我们只需要一个指向第一个元素的指针。如果我们想要得到其他元素的地址，我们只需向该指针添加一个偏移量。

One other point: usually if a C function wants an array pointer, it also has an argument for the array length. In most cases you can give it dArray.length, but sometimes it's actually asking for the size in bytes, rather than the number of elements.

另一个要点:通常如果C函数想要一个数组指针，它也有一个数组长度的参数。在大多数情况下，你可以给它dArray。长度，但有时它实际上要求的是字节的大小，而不是元素的数量。

#1