As I told you earlier the concept of arrays is very closely related to pointers. Arrays will work faster by using pointers rather than using a subscript. So it is always recommended to access arrays by using pointers. In the last tutorial I gave a brief overview on 2D arrays in C. Today I will discuss the usage of 2D arrays with pointers. This is one of the most complex topics of C programming, so I would like to suggest you to read this tutorial with full concentration.
2D Arrays with Pointers
A 2D array is nothing but a combination of 1D arrays. To prove my point I would like to show you an example.
#include<stdio.h>
int main( )
{
int s[4][2]={
{542,43},
{154,354},
{432,54},
{435,435}
};
int x;
for(x=0;x<=3;x++)
printf("n Address of %d th 1-D array = %u",x,s[x]);
return 0;
}
Output
Explanation
- In the beginning I have declared a 2D array with 4 rows and 2 columns and also initialized it. So we can say that this 2D array is a collection of four 1D arrays having 2 elements each.
- After that I have declared integer variable x which will act as a loop counter.
- Now I have started the for loop with one printf() function. Consider carefully the arguments in printf() function. I have given two arguments which are x and s[x].
- As you can see I am only accessing the 2D array with one dimension. So it will give the addresses of only 1D arrays. s[0] will show the address of first element of first 1D array, s[1] will show address of first element of second 1D array and so on.
Access 2D Array Using Pointer Notation
The best way to learn it is through a program.
#include<stdio.h>
int main()
{
int s[4][2]={
{ 542, 43 },
{ 154, 354 },
{ 432, 54 },
{ 435, 435 }
} ;
int x;
printf(" %dn",s[2][1]);
printf(" It will give you address of 1st element of 3rd 1D array - %u n",s[2]);
printf(" It will give you address of 2st element of 3rd 1D array - %u n",s[2]+1);
printf(" Value at that address %d n", *(s[2]+1));
printf(" Alternate way of accessing that address %d n",*(*(s+2)+1));
return 0;
}
Output
