是否允许/正确定义零长度可变长度数组？ [英] Are zero-length variable length arrays allowed/well defined?

问题描述

我正在C99中编程，并且在代码的一部分中使用了可变长度数组。我知道在C89中不允许使用零长度数组，但是我不确定C99和可变长度数组。

I'm programming in C99 and use variable length arrays in one portion of my code. I know in C89 zero-length arrays are not allowed, but I'm unsure of C99 and variable length arrays.

简而言之，以下定义明确的行为是吗？

In short, is the following well defined behavior?

int main()
{
    int i = 0;
    char array[i];
    return 0;
}

推荐答案

不，零长度数组被C语言明确禁止，即使它们是通过运行时大小值（如您的代码示例中）作为VLA创建的。

No, zero-length arrays are explicitly prohibited by C language, even if they are created as VLA through a run-time size value (as in your code sample).

6.7.5.2数组声明符

...

5 如果大小是不是整数常量
表达式：如果它出现在函数原型范围的声明中，则
会被视为用*替换； 否则，每次对
进行评估时，其值都应大于零。

5 If the size is an expression that is not an integer constant expression: if it occurs in a declaration at function prototype scope, it is treated as if it were replaced by *; otherwise, each time it is evaluated it shall have a value greater than zero.

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