c - c在第一次定义时如何给指针数组赋值？

Question

我有一个 int 指针数组。

int *ints[3];

定义这个数组后内存会发生什么变化？存储的初始指针值是多少？当我尝试取消引用一个值时，我得到一个 segmentation fault，它告诉我这些值是任意的。

Answer 1

这取决于数组的存储。

• 如果它有静态存储，即在任何函数之外声明或在函数中用 static 声明，则所有元素都将为 NULL

• 如果在函数中声明，没有static，它将有自动存储且初始值不确定

标准恰好在这件事上非常清楚并且很有帮助:

If an object that has automatic storage duration is not initialized explicitly, its value is indeterminate. If an object that has static or thread storage duration is not initialized explicitly, then:

• if it has pointer type, it is initialized to a null pointer;
• if it has arithmetic type, it is initialized to (positive or unsigned) zero;
• if it is an aggregate, every member is initialized (recursively) according to these rules, and any padding is initialized to zero
  bits;