c++ trying to understand clockwise rules for deciphering complicated syntax

Question

I have the following code:

int ia[3][4] = {    //
{0, 1, 2, 3},   //
{4, 5, 6, 7},   //
{8, 9, 10, 11}  //
};

int (*p4)[4] = ia;
cout << \"(*(p4 + 0))         


        

Answer 1

I don't understand the last one how it arrives at 1.

Undefined behavior got you there.

Due to operator precedence (the array indexing operator binds tighter than the pointer dereference operator),

*(p4 + 0)[3] is the same as:
*((p4 + 0)[3]), which is the same as:
*(p4[3]), which is the same as:
p4[3][0].

For your array. the valid indices for the first dimension are: 0, 1, and 2. Accessing the array using the index value of 3 accesses memory beyond valid range, leading to undefined behavior.