Arrays

All arrays consist of contiguous memory locations. The lowest address corresponds to the first element and the highest address to the last element.

What are Arrays?

An array is a sequence of data item of homogeneous value(same type).

Memory Representation of arrays.

int marks[5] = {51,62,43,74,55};

Here an array marks of 5 elements is created. Figure shows its memory representation.

Array Declaration

To declare an array in C, a programmer specifies the type of the elements and the number of elements required by an array as follows.

type arrayName[array size];

This is called a single-dimensional array. The arraySize must be an integer constant greater than zero and type can be any valid C data type. For example, to declare a 10-element array called balance of type double, use this statement:

double balance[10];

Array Initialization

int num[6] = {4,5,3,6,34,56};

int num[] = {4,5,3,6,34,56};

float press[] = { 12.4,5.6,7.5,3.3,2};

Accessing Array Elements

int arr[5] = {12,5,6,3,4};

int x= arr[3];

int y= arr[4];

int z= arr[0]+arr[2];

printf("%d %d %d",x,y,z);

output: 3 4 18

printf("%d", arr[5]);

output: Error - Array Index Out of bound

Basic Array Program

#include <stdio.h>
 
int main ()
{
   int n[ 10 ]; /* n is an array of 10 integers */
   int i,j;
 
   /* initialize elements of array n to 0 */         
   for ( i = 0; i < 10; i++ )
   {
      n[ i ] = i + 100; /* set element at location i to i + 100 */
   }
   
   /* output each array element's value */
   for (j = 0; j < 10; j++ )
   {
      printf("Element[%d] = %d\n", j, n[j] );
   }
 
   return 0;
}

Output:

Element[0] = 100
Element[1] = 101
Element[2] = 102
Element[3] = 103
Element[4] = 104
Element[5] = 105
Element[6] = 106
Element[7] = 107
Element[8] = 108
Element[9] = 109

Another Example