We should think of multidimensional arrays in a
different way in C:
A 2D array is really a 1D array, each of whose elements
is itself an array
Hence
a[n][m] notation.
Array elements are stored row by row.
When we pass a 2D array to a function we must specify the
number of columns and the number of rows is irrelevant.
The reason for this is pointers again. C needs to know how
many columns in order that it can jump from row to row in memory.
Considerint a[5][35] to be passed in a function:
We can do:
f(int a[][35]) {.....}
or even:
f(int (*a)[35]) {.....}
We need parenthesis (*a) since [] have a higher precedence than *
So:
int (*a)[35]; /*declares a pointer to an array of 35 int */
int *a[35]; /*declares an array of 35 pointers to int */
Now lets look at the (subtle) difference between pointers
and arrays. Strings are a common application of this.
Consider:
char *name[10];
char Aname[10][20];
We can legally do name[3][4] and Aname[3][4] in C.
