用C访问数组元素的不同方式 [英] Different way of accessing array elements in C

问题描述

我是一个C语言编程课程的助教，和我遇到以下行C $ C $的c传来：

I am a teaching assistant for a C programming course, and I came across the following line of C code:

> char str[] = "My cat's name is Wiggles.";
> printf("%c %c %c %c\n", str[5], *(str + 5), *(5 + str), 5[str]);

我从来没有跨越最后一个参数（ 5 [STR] ）之前来了，也没有我的教授。我不认为这是K＆放提及; R和C的Primer Plus。我发现了这片code在一套技术面试问题。有谁知道为什么C允许您访问数组元素的方式也？我从来没有听说过的索引是组括号及括号内的数组的名称之外的。

I never came across the very last argument (5[str]) before, and neither did my professor. I don't think it's mentioned in K&R and C Primer Plus. I found this piece of code in a set of technical interview questions. Does anyone know why C allows you to access an array element that way also? I never heard of an index being outside the set of brackets and the name of an array inside the brackets.

您的帮助将大大AP preciated！

Your help will be greatly appreciated!

推荐答案

完全有效C.从维基百科：

类似地，由于前pression一个[i]为语义上等同于*（A + I），这又相当于*第（i + a）中，前pression也可以写成作为I [A]（虽然这种形式很少使用）。

Similarly, since the expression a[i] is semantically equivalent to *(a+i), which in turn is equivalent to *(i+a), the expression can also be written as i[a] (although this form is rarely used).

古怪，但有效。

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