Introduction of Arrays

  • An array is a data structure used to process multiple elements with the same data type when a number of such elements are known.
  • Arrays form an important part of almost all-programming languages.
  • It provides a powerful feature and can be used as such or can be used to form complex data structures like stacks and queues.
  • An array can be defined as an infinite collection of homogeneous(similar type) elements.
  • This means that an array can store either all integers, all floating point numbers, all characters, or any other complex data type, but all of same type.
  • Arrays are always stored in consecutive memory locations.

Types of Arrays

There are two types of Arrays

  • One Dimensional Arrays
  • Two Dimensional Arrays

One Dimensional Arrays

  • A one-dimensional array is one in which only one subscript specification is needed to specify a particular element of the array.
  • A one-dimensional array is a list of related variables. Such lists are common in programming.

One-dimensional array can be declared as follows : 

 Data_type var_name[Expression];

Initializing One-Dimensional Array

ANSI C allows automatic array variables to be initialized in declaration by constant initializers as we have seen we can do for scalar variables.

These initializing expressions must be constant value; expressions with identifiers or function calls may not be used in the initializers.

The initializers are specified within braces and separated by commas.

 int ex[5] = { 10, 5, 15, 20, 25} ;
 char word[10] = { 'h', 'e', 'l', 'l', 'o' } ;

Example:-

// Program to print the element of Array
#include <stdio.h>
int main()
{
    /*an array with 5 rows and 2 columns*/
    int a[5][2] = {{0,0},{1,2},{2,4},{3,6},{4,8}};
    int i,j;
    /* Output each array elements value*/
    for(i=0; i<5; i++);
    {
      for(j=0; j<2; j++);
      {
        printf("a[%d][%d]=%d",i,j,a[i][j]);
      }
    }
    return 0;
}

Output:-

 a[0][0] = 0
 a[0][1] = 0
 a[1][0] = 1
 a[1][1] = 2
 a[2][0] = 2
 a[2][1] = 4
 a[3][0] = 3
 a[3][1] = 6
 a[4][0] = 4

 

Passing Arrays to Function

  • Arrays like other simple variables can be passed to function. To pass, its name is written inside the argument list in the call statement.
  • Arrays are by default passed to function by call by reference method because array name is itself a pointer to the first memory location of the array.
  • However we can pass individul array elements through call by value method also.