Question

Why can’t you declare a 2D array argument in a function as you do with a normal array?

 void F(int bar[]){} //Ok
 void Fo(int bar[][]) //Not ok
 void Foo(int bar[][SIZE]) //Ok

Why is it needed to declare the size for the column?

Answer 1

You can’t write void Foo(int bar[][]), because bar decays to a pointer. Imagine following code:

void Foo(int bar[][]) // pseudocode
{
    bar++; // compiler can't know by how much increase the pointer
    // as it doesn't know size of *bar
}

So, compiler must know size of *bar, therefore size of rightmost array must be provided.