INDEXING POINTERS

INDEXING POINTERS

                        When an array is declared, the compiler allocates a base address and sufficient amount of storage space for storing all the elements of the array in successive memory locations.  The name of the array is the beginning address (first element index 0) of the array, called the base address.  So, that the array name is referred to as an address constant.

            Example:        int x[5] = {10,20,30,40,50};

           

Here,

                        x = &x[0] = &x   all are referred to the address location 1000.

With the relationship between the array and pointer, array subscripts can also be defined in terms of pointer arithmetic operations which are known as indexing pointers.

For single dimensional arrays,

            int x[3], i=0;

            &x[0] = x+0                            x[0] = *(x+0)

           

            i.e., &x[i] = x+i                       x[i] = *(x+i)

Similarly, for double dimensional arrays,

            &x[i][j] = (*(x+i)+j)                x[i][j] = *(*(x+i)+j)

                                                                       

            #include<stdio.h>

#include<conio.h>

main()

{

int i,a[5] = {10,20,30,40,50};

clrscr();

for(i=0;i<5;i++)

printf("a[%d] : %d",i,*(a+i));

getch();

}