写原型为恰恰16整数数组功能 [英] Write the prototype for a function that takes an array of exactly 16 integers

问题描述

一个面试问题问我写的原型为一个C函数，它正好是16整数数组，我想知道这可能是什么？也许一个函数的声明是这样的：

One of the interview questions asked me to "write the prototype for a C function that takes an array of exactly 16 integers" and I was wondering what it could be? Maybe a function declaration like this:

void foo(int a[], int len);

或者其他什么东西？

Or something else?

和怎么样，如果语言是C ++呢？

And what about if the language was C++ instead?

推荐答案

在C，这需要一个指向16整数数组：

In C, this requires a pointer to an array of 16 integers:

void special_case(int (*array)[16]);

这将与被称为：

int array[16];
special_case(&array);

在C ++中，你可以使用一个引用到一个数组，也如图的纳瓦兹​​答案。 （这个问题询问℃的称号，并原本只在标签中提到C ++）。

In C++, you can use a reference to an array, too, as shown in Nawaz's answer. (The question asks for C in the title, and originally only mentioned C++ in the tags.)

这是使用的一些变种任何版本：

Any version that uses some variant of:

void alternative(int array[16]);

最后等于为：

void alternative(int *array);

这将接受阵列的任何尺寸，在实践中。

which will accept any size of array, in practice.

现在的问题是问 - 确实 special_case（）真的prevent被传递不同大小的数组。答案是是。

The question is asked - does special_case() really prevent a different size of array from being passed. The answer is 'Yes'.

void special_case(int (*array)[16]);

void anon(void)
{

    int array16[16];
    int array18[18];
    special_case(&array16);
    special_case(&array18);
}

编译器（GCC 4.5.2上的MacOS X 10.6.6，因为它发生）抱怨（警告）：

The compiler (GCC 4.5.2 on MacOS X 10.6.6, as it happens) complains (warns):

$ gcc -c xx.c
xx.c: In function ‘anon’:
xx.c:9:5: warning: passing argument 1 of ‘special_case’ from incompatible pointer type
xx.c:1:6: note: expected ‘int (*)[16]’ but argument is of type ‘int (*)[18]’
$

切换到GCC 4.2.1 - 为苹果公司提供 - 和警告是：

Change to GCC 4.2.1 - as provided by Apple - and the warning is:

$ /usr/bin/gcc -c xx.c
xx.c: In function ‘anon’:
xx.c:9: warning: passing argument 1 of ‘special_case’ from incompatible pointer type
$

在4.5.2警告较好，但实质是一样的。

The warning in 4.5.2 is better, but the substance is the same.

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