array[100] = {0} 如何将整个数组设置为 0?
编译器如何填充char array[100] = {0};中的值?它背后的魔力是什么?
How does the compiler fill values in char array[100] = {0};? What's the magic behind it?
我想知道编译器内部是如何初始化的.
I wanted to know how internally compiler initializes.
推荐答案
这不是魔法.
此代码在 C 中的行为在 C 规范的第 6.7.8.21 节(C 规范在线草案):对于没有指定值的元素，编译器将指向 NULL 的指针和算术类型初始化为零(并递归地将其应用于聚合).
The behavior of this code in C is described in section 6.7.8.21 of the C specification (online draft of C spec): for the elements that don't have a specified value, the compiler initializes pointers to NULL and arithmetic types to zero (and recursively applies this to aggregates).
此代码在 C++ 中的行为在 C++ 规范的第 8.5.1.7 节(C++ 规范在线草案):编译器聚合初始化没有指定值的元素.
The behavior of this code in C++ is described in section 8.5.1.7 of the C++ specification (online draft of C++ spec): the compiler aggregate-initializes the elements that don't have a specified value.
另外，请注意，在 C++(但不是 C)中，您可以使用空的初始化列表，导致编译器聚合初始化数组的所有元素:
Also, note that in C++ (but not C), you can use an empty initializer list, causing the compiler to aggregate-initialize all of the elements of the array:
char array[100] = {};
至于当你这样做时编译器可能会生成什么样的代码，看看这个问题:来自数组 0-initialization 的奇怪程序集
As for what sort of code the compiler might generate when you do this, take a look at this question: Strange assembly from array 0-initialization
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