取消引用void指针到指针数组 [英] De-referencing void pointer to a pointer array

问题描述

我正在使用学校提供给我的线程库，无法理解如何将指针数组的引用传递给方法，或者说，我在解引用和使用指针数组时遇到了麻烦.

I'm using a threading library given to me at school and having trouble understanding how to pass a reference of an array of pointers to a method, or rather, I'm having trouble de-referencing and using the pointer array.

我(相信我)理解的情况是这样的:

The situation that I (believe I) understand is this:

int main(void)
{
    Foo* bar = new Foo();

    // Passing instance of Foo pointer by reference 
    CThread *myThread = new CThread(MyFunction, ACTIVE, &bar);

    return 0;
}

UINT __stdcall MyFunction(void *arg)
{
    Foo* bar = *(Foo*)(arg); 

    return 0;
}

我正在创建一个指向Foo对象的指针，并将其通过引用传递给运行MyFunction的线程，该线程接受一个void指针作为其参数.然后，MyFunction将"arg"强制转换为Foo指针，并对其取消引用以获取原始对象.

I'm creating a pointer to a Foo object and passing it by reference to a thread running MyFunction, which accepts a void pointer as its argument. MyFunction then casts "arg" to a Foo pointer and de-references it to get the original object.

当我想传递一个Foo指针数组而不是一个数组时，就会出现我的问题:

My problem arises when I want to pass an array of Foo pointers instead of just one:

int main(void)
{
    Foo* barGroup[3] = 
    {
        new Foo(),
        new Foo(),
        new Foo()
    };

    // Passing instance of Foo pointer by reference 
    CThread *myThread = new CThread(MyFunction, ACTIVE, &barGroup);

    return 0;
}

UINT __stdcall MyFunction(void *arg)
{
    // This is wrong; how do I do this??
    Foo* barGroup[3] = *(Foo[]*)(arg); 

    return 0;
}

推荐答案

将 MyFunction(& barGroup); 替换为 MyFunction(barGroup); (从而传递指针)指向第一个元素，而不是指向整个数组的指针)，然后使用嵌套的指针:

Replace MyFunction(&barGroup); with MyFunction(barGroup); (thus passing a pointer to the first element instead of a pointer to the entire array) and use a nested pointer:

Foo** barGroup = (Foo**)(arg); 

然后，您可以简单地使用 barGroup [0] ， barGroup [1] 和 barGroup [2] .

Then you can simply use barGroup[0], barGroup[1] and barGroup[2].

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