c programming

Question

#include<stdio.h>
main()
{
int a[][3] = {1, 2, 3, 4, 5, 6};
int (*ptr)[3] = a;
printf("%d %d ", (*ptr)[1], (*ptr)[2]);
++ptr;
printf("%d %d\n", (*ptr)[1], (*ptr)[2]);
return 0;
}

explain this program?

Answer 1

${\color{Red} {int (*ptr)[3]} } \rightarrow$ This is a pointer to an array of $3 \ integers$

${\color{Blue} {int (*ptr)[3] = a}} \rightarrow$    it stores address of $a$ .

${\color{Blue} {(*ptr)[1] }} \rightarrow$   it is $a[0][1]$ which is $2$

${\color{Blue} {(*ptr)[2] }} \rightarrow$    it is $a[0][2]$ which is $3$

${\color{Blue} {(++ptr) }} \rightarrow$it is  increased .it accesses  to $2^{nd}$ row of the  array 

${\color{Blue} {(*ptr)[1] }} \rightarrow$   it is $a[1][1]$ which is $5$

${\color{Blue} {(*ptr)[2] }} \rightarrow$    it is $a[1][2]$ which is $6$