Initialising a 2-Dimensional Array in C programming language

How do we initialize a two-dimensional array? As simple as this...

int  stud[4][2] = {
    { 1234, 56 },
    { 1212, 33 },
    { 1434, 80 },
    { 1312, 78 }
                      } ;

or even this would work...

int stud[4][2] = { 1234, 56, 1212, 33, 1434, 80, 1312, 78 } ;

of course with a corresponding loss in readability. It is important to remember that while initializing a 2-D array it is necessary to mention the second (column) dimension, whereas the first dimension (row) is optional. Thus the declarations,

int  arr[2][3] = { 12, 34, 23, 45, 56, 45 } ;
int  arr[ ][3] = { 12, 34, 23, 45, 56, 45 } ;

are perfectly acceptable,
whereas,

int  arr[2][ ] = { 12, 34, 23, 45, 56, 45 } ;
int  arr[ ][ ] = { 12, 34, 23, 45, 56, 45 } ;

would never work.