Can a two-dimensional array in C be initialized without explicit size?

Question

I have a question regarding two-dimensional arrays in C. I know now (from direct compiler experience) that I can\'t initialize such an array analogously to one-dimensional a

Answer 1

Not a direct answer to those questions in the original post, I just want to point out that what the asker propose may be not such a good or useful idea.

---

The compiler indeed can infer from

int multi_array[][] = {
  {1,2,3,4,5},
  {10,20,30,40,50},
  {100,200,300,400,500}
};

the structure of multi_array.

But when you want to declare and define a function (this declaration and definition could be in another compilation unit or source file) that supposes to accept multi_array as one of its argument, you still need to do something like

int foo(..., int multi_array[][COL], ...) { }

Compiler needs this COL to do proper pointer arithmetic in foo().

Usually, we define COL as a macro that will be replaced by an integer in a header file, and use it in the definitions of multi_array and foo():

int multi_array[][COL] = { ... };

int foo(..., int multi_array[][COL], ...) { }

By doing this, it is easy to make sure they are the same. And let compiler to infer the structure of multi_array according to its initialization, when you give it a wrong initialization, you actually introduce a bug in your code.