C langugae : Arrays

An array is a collection of variables of the same type that are referred to through a common name. A specific element in an array is accessed by an index. In C, all arrays consist of contiguous memory locations. The lowest address corresponds to the first element and the highest address to the last element. Arrays can have from one to several dimensions. The most common array is the string, which is simply an array of characters terminated by a null.
Initialization of Array
To initialize an array explicitly when you define it, you must use an initialization list: this is a comma-separated list of initializers, or initial values for the individual array elements, enclosed in braces. An example:
int a[4] = { 1, 2, 4, 8 };
This definition gives the elements of the array a the following initial values:
a[0] = 1, a[1] = 2, a[2] = 4, a[3] = 8
Generating a Pointer to an Array
You can generate a pointer to the first element of an array by simply specifying the array name, without any index. For example, given
int sample[10];
int *p;
p = sample;

Element	a[0]	a[1]	a[2]	a[3]	a[4]	a[5]	a[6]
Address	1000	1001	1002	1003	1004	1005	1006

Values assigned to elements by index

Element	a[0]	a[1]	a[2]
Index	0	2	4

Single-Dimension Arrays
C99 has introduced element designators to allow you to associate initializers with specific elements . To specify a certain element to initialize, place its index in square brackets. In other words, the general form of an element designator for array elements is:
[constant_expression]
type var_name[size];
int a[4] = { 1, 2 };
int a[ ] = { 1, 2, 0, 0 };
#define A_SIZE 20
Consider the following example of array declarations:
//To sort the series using array. #include< stdio.h >
#include< conio.h >
void main()
{
int a[10];
clrscr();
fun(a[10]);
getch();
}
fun(int s[10])
{
int j,r,p;
printf("enter the sized array");
scanf("%d",&p);
printf("ener the array element\n");
for(r=0;r scanf("%d",&s[r]);
for(r=0;r {
for(j=0;j {
if(s[j]<=s[j+1])
{
int temp;
temp=s[j];
s[j]=s[j+1];
s[j+1]=temp;
}
}
}
for(r=0;r printf("%d\n",s[r]);
return 0;
}
Multidimensional Arrays
C allows arrays of more than two dimensions. The general form of a multidimensional array declaration is
type name[Size1][Size2][Size3] . . .[SizeN];
Arrays of more than three dimensions are not often used because of the amount of memory they require. For example, a four-dimensional character array with dimensions 10,6,9,4 requires 10 * 6 *9 *4 or 2,160 bytes. If the array held 2-byte integers, 4,320 bytes would be needed. If the array held doubles (assuming 8 bytes per double), 17,280 bytes would be required. The storage required increases exponentially with the number of dimensions. For example, if a fifth dimension of size 10 was added to the preceding array, then 172,800 bytes would be required.
In multidimensional arrays, it takes the computer time to compute each index. This means that accessing an element in a multidimensional array can be slower than accessing an element in a single-dimension array.
When passing multidimensional arrays into functions, you must declare all but the leftmost dimension. For example, if you declare array m as
int m[4][3][6][5];

Two-dimensional array(Matrices)