数组如何定义索引开头_为什么数组索引在C中以0开头？

柔光的暖阳◎ 2022-12-07 13:59 180阅读 0赞

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数组如何定义索引开头

Why array indexing starts with 0 in C, C++, Java and most of other programming languages is one of the common confusion among programmers.

为什么在C，C ++，Java和大多数其他编程语言中，数组索引以0开头是程序员之间常见的困惑之一。

In this article I will tell you the reason behind it.

在本文中，我将告诉您其背后的原因。

![Array in C][]

[Image Source][]

[图片来源][Image Source]

## 为什么数组索引在C中以0开头？ **(**Why Array Indexing Starts with 0 in C?**)** ##

Lets try to understand this by taking one example in C. We can declare an array of size 5 in following way.

让我们尝试通过在C中举一个例子来理解这一点。我们可以通过以下方式声明大小为5的数组。

**int a\[5\];**

**int a \[5\];**

Here **a** itself is a pointer which contains the memory location of first element of the array.

这里**，**本身就是一个指针，它包含数组第一个元素的存储位置。

Now for accessing the first element we will write **a\[0\]** which is internally decoded by compiler as **\*(a + 0)**.

现在，为了访问第一个元素，我们将编写**a \[0\]** ，它由编译器在内部解码为**\*(a + 0)** 。

In the same way the second element can be accessed by **a\[1\]** or **\*(a + 1)**. As **a** contains the address of first element so for accessing second element we have to add 1 to it. Thats why here we have written **\*(a +1)**.

同样，可以通过**a \[1\]**或**\*(a + 1)**访问第二个元素。 **作为**包含第一个元素的地址，以便访问第二个元素，我们必须1添加到它。 这就是为什么我们在这里编写**\*(a +1)** 。

In array the index describes the offset from the first element, i.e. the distance from the first element.

在数组中，索引描述距第一个元素的偏移量，即距第一个元素的距离。

Now lets assume that array indexing starts with 1 instead of 0. In this case for accessing the first element we have to write **a\[1\]** which is internally decoded as **\*(a + 1 – 1)**.

现在，假设数组索引从1而不是0开始。在这种情况下，为了访问第一个元素，我们必须编写**a \[1\]** ，该内部解码为**\*(a +1-1)** 。

Observe here that we have to perform one extra operation i.e. subtraction by 1. This extra operation will greatly decrease the performance when the program is big.

在这里观察到，我们必须执行一个额外的操作，即减1。当程序很大时，此额外的操作将大大降低性能。

Thats why to avoid this extra operation and improve the performance, array indexing starts with 0 in C, C++, Java, etc.

这就是为什么要避免这种额外的操作并提高性能的原因，在C，C ++，Java等中，数组索引从0开始。

Comment below if you have any queries regarding above article. Do share it if you found this information valuable.

如果您对以上文章有任何疑问，请在下面评论。 如果发现此信息有价值，请共享它。

> 翻译自: [https://www.thecrazyprogrammer.com/2017/03/why-array-indexing-starts-with-0-in-c.html][https_www.thecrazyprogrammer.com_2017_03_why-array-indexing-starts-with-0-in-c.html]

数组如何定义索引开头

[df11be90a2d316f2ec19c2dff7bc87a2.png]: /images/20221123/077af6d8f429411eaf81dabef730f12e.png
[Array in C]: /images/20221123/92cda21178314a1daa2ce0cbb3fccfc7.png
[Image Source]: https://www.programiz.com/c-programming/c-arrays
[https_www.thecrazyprogrammer.com_2017_03_why-array-indexing-starts-with-0-in-c.html]: https://www.thecrazyprogrammer.com/2017/03/why-array-indexing-starts-with-0-in-c.html