Understanding Array/Pointer Conversion

/* see: C11 Standard - 6.3.2.1 Other Operands - Lvalues, arrays, and function designators(p3)
 *      http://port70.net/~nsz/c/c11/n1570.html#6.3.2.1p3
 */
#include <stdio.h>

void printmyarr (int pt[][4], int nptrs)
{
    int nelem = sizeof *pt/sizeof **pt;     /* number of int per-array */

    for (int i = 0; i < nptrs; i++) {       /* iterate each row */
        for (int j = 0; j < nelem; j++)     /* iterate each col */
            printf (" %4d", pt[i][j]);      /* output int */
        putchar ('\n');                     /* tidy up with newline */
    }
}

void printwptr (int (*pt)[4], int nptrs)
{
    int nelem = sizeof *pt/sizeof **pt;     /* number of int per-array */

    while (nptrs--) {               /* iterate nptrs times */
        int *p = *pt++,             /* initialize p to row, advance pt */
            n = nelem;              /* initialize n to nelem */
        while (n--)                 /* iterate n times */
            printf (" %4d", *p++);  /* output element, advance to next */
        putchar ('\n');             /* tidy up with newline */
    }
}

int main (void) {

    int myarr[][4]  =  {{  12,   16,   19,   20},
                        {   5,   99,  102,  200},
                        {  12,   20,   25,  600},
                        {  65,   66,  999, 1000}};

    puts ("print with indexes:");
    printmyarr (myarr, sizeof myarr/sizeof *myarr);

    puts ("\nprint with pointers:");
    printwptr (myarr, sizeof myarr/sizeof *myarr);
}