这个C结构分配是什么意思？

Question

I'm trying to read through some C source code and I've come across a structure assignment that I don't understand:

static struct sym_table *sym_array = (struct sym_table *) 0;

I understand that the left-hand-side is trying to initialize a pointer to a structure of type 'sym_table' (which is defined elsewhere); however, I am struggling to understand the right-hand-side. It's probably fairly simple, but I can't find any similar examples of this sort of assignment in any of the online C tutorials that I've seen.

If anyone can shed some light on it, I would really appreciate it!

Answer 1

static struct sym_table *sym_array = (struct sym_table *) 0;

is a slightly cumbersome way to set a pointer to NULL , NULL being defined in stdio.h as ((void *)0) . You'd be better off with:

static struct sym_table *sym_array = NULL;

Answer 2

The right-hand-side is the equivalent of NULL pointer. But here , it is a NULL pointer of type (struct sym_table *)

Answer 3

this the Stroustrup way. He hates macros. So he always uses 0 in his code or eventually when keyword nullptr was introduced the nullptr . I think it is from the C++ code or from the program written by someone who usually uses C++.