1D array decays to pointer, but 2D array doesn't do so, why? [duplicate]

Answer 1

It does decay. An expression whose type is "array of T" decays into a pointer to its first element. For a 2-dimensional array of T, the first element has type array of T. So:

int arr[5];

In most contexts, arr has type "pointer to int". Now apply the same rule to a 2-dimensional array:

int arr2[5][5];

Here, arr2 has type "pointer to array of 5 int". Note that the type of this object is not "array of T", so it does not decay further.