在C ++中用字符串索引的整数 [英] integer indexed with a string in c++

问题描述

可能重复:
在C数组中为什么如此? a [5] == 5 [a]

Possible Duplicate:
In C arrays why is this true? a[5] == 5[a]

这怎么可能是有效的C ++?

How is it possible that this is valid C++?

void main()
{
  int x = 1["WTF?"];
}

在VC ++ 10上，它将进行编译，并且在调试模式下，语句后的x值为84.

On VC++10 this compiles and in debug mode the value of x is 84 after the statement.

这是怎么回事?

推荐答案

数组下标运算符是可交换的.等效于int x = "WTF?"[1];在这里，"WTF?"是5个char s的数组(它包含空终止符)，并且[1]给我们第二个字符，它是'T'-隐式转换为int给出值84.

Array subscript operator is commutative. It's equivalent to int x = "WTF?"[1]; Here, "WTF?" is an array of 5 chars (it includes null terminator), and [1] gives us the second char, which is 'T' - implicitly converted to int it gives value 84.

Offtopic:代码段不是有效的C ++，实际上-main必须返回int.

Offtopic: The code snippet isn't valid C++, actually - main must return int.

您可以在此处阅读更多深入的讨论:在C数组为何如此? a [5] == 5 [a]

You can read more in-depth discussion here: In C arrays why is this true? a[5] == 5[a]

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