在C数组指针的试验 [英] Experimenting with pointers of arrays in C

问题描述

我有一个数组 A ，其值我想通过另一个函数修改。这是code，我有：

I have an array a whose values I wish to modify through another function. This is the code that I have:

#include "stdlib.h" 
#include "stdio.h"

void myfunc(int* );

int main() {

    int *a, i;

    a = (int*) calloc(10,sizeof(int));
    myfunc(&a);

    for (i=0; i<10; i++) printf("%d\n", a[i]);

    return 0;
}

void myfunc(int* a) {

    int i;

    for (i=0; i<10; i++) *a[i] = i;
}

显然东西是错误与我的语法，我想知道，如果有人可以帮我一把：）

Obviously something is wrong with my syntax and I Was wondering if someone could lend me a hand :)

谢谢！

推荐答案

在主函数中，你已经有了一个指向一个整数， A 。那么你该指针的地址传递给 MYFUNC ，但 MYFUNC 期待一个指向一个int，而不是一个指针一个指针为int。您需要将到 MYFUNC 通话改成这样：

In the main function, you've got a pointer to an integer, a. Then you pass the address of this pointer to myfunc, but myfunc is expecting a pointer to an int, not a pointer to a pointer to an int. You need to change your call to myfunc to this:

myfunc(a);

不过，你也有内部的 MYFUNC 的一个问题。你不需要解引用 A [I] 因为这指数到一个数组 A 。这些都是（有效），同样的事情：

But, you've also got a problem inside myfunc. You don't need to dereference a[i] since that indexes into an array a. These are (effectively) the same thing:

a[i]

和

*(a+i)

（这是不是100％，我认为，因为在C指针和数组不完全一样的东西，所以一些专家的C程序员可以指正）

(This isn't 100%, I think, because in C pointers and arrays are not completely the same thing, so some expert C programmer can correct me)

你可能只是得到一个有点绕指针和数组语法的收集困惑：

You're probably just get a bit confused by the collection of syntax around pointers and arrays:

&a
*a
a[i]
*(a+i)

第一个是 A ，第二个指针引用 A 为指针，第三个是一个地址索引到一个数组，第四个是取消引用 A 与指针的偏移量。

The first one is the address of a, the second dereferences a as a pointer, the third is an index into an array and the fourth is dereferencing a as a pointer with an offset.

您只需要做到这一点 *（A []​​）如果你有一个指针数组，而不是一个指针为int。

You would only want to do this *(a[i]) if you had an array of pointers, not a pointer to an int.

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