Arrays

Let us see an  Array  with following  points:

1. What is an Array?
2. Declaration of an Array.
3. Types of Array.
4. Initialization of an Arrays.
5. Solved Case Studies.

• What is an Array?

Array can be defined as follows:

1. It is a group of same type of elements.
2. It is a set of values of same data type.
3. Related data items share the common name .
4. Single name can be used to represent collection of same type of items.

E.g   Array of int ,Array of float ,Array of char etc.

• Declaration of an Array

Let us see how to declare Array in  C Language

Syntax:

      data_type Array_name[size_of_array];

This is one dimensional array where

         [] are used to specify Array_name is an array and inside bracket we mention the size of array means how many elements are hold by array_name

data_type Array_name[no_of_rows][no_of_column];

This is Two dimensional array

• Types of Array.

The type of an array depends on number of dimensions used.

The types are

1. 1-D array(One dimension Array)
2. 2-D Array(Two Dimension Array)
3. Multi Dimension array

• 1-D array(One dimension Array)

In this data is stored linearly in consecutive locations i.e it reserve consecutive memory locations for specified type of data with size_of_array.

e.g 

 int roll[10];

It declares an integer array roll with size 10.i.e Array with name roll can store 10 integer elements.

Each element is used with array name and it's subscript/index.

For array index always starts with 0 and ends with (size_of_array-1)

e.g

roll[0] -->This is the first element of an array

roll[1]

.

.

.

roll[9] -->This is the last element of an array.

Memory allocated for this array is calculated as follows:

Assume size of int is 2 bytes

Total consecutive Memory reserved/allocated is 2*10=20 bytes 

• 2-D Array(Two Dimension Array)

In this type data is stored in table format by using rows and columns

Syntax: 

1) int abc[10][5]; --> abc array has 10 rows and 5 columns

   i.e it can store 10*5=50 integer elements into array abc

2) char name[2][10]; -->name array has 2 rows and 10 columns

  i.e it can store 2*10=20 character elements into array name

Memory allocation for 2-D array.

Total memory for (rows*column) elements will be allocated.

In above 1st example ,

Assume size of int is 2 bytes

Total consecutive Memory reserved/allocated is 2*50=100 bytes

In above 2nd example ,

Assume size of char is 1 bytes .
Total consecutive Memory reserved/allocated is 1*20=20 bytes.

Each element in 2-D is used with array name and it's 2 subscript/index

e.g 

abc[0][0] -->this is the first element of an array 

abc[0][1]

..

abc[9][4] -->This is the last element of an array

• Multi Dimension array

Similar to 2D this uses multiple dimensions.

e.g

 int xyz[2][3][4];

• Initialization of an Arrays

Initialization means assigning initial values to elements in the array i.e at the time of declaration

1-D Array Initialization

   type arr-name[size]={comma separated list of values};

e.g 

int roll[10]={1,2,3,4,5,6,7,8,9,10};

   //it will initialize all 10 elements of roll array

int roll[10]={1,2,3,4};  

  //it will initialize only 1st 4 elements and remaining to zero(0)

Array Initialization without size

int roll[]={1,2,3,4,5,6}; 

  //It will declare roll array to contain 6 elements with initial vales as per given in list

char name[]={'R','I','Y','A'};

2-D Array Initialization

int roll[2][4]={1,1,1,1,2,2,2,2};

 //initialize row by row

 //first row to 1 and second row to 2

also written as

int roll[2][4]={{1,1,1,1},{2,2,2,2}};

if value missing in initialization then automatically set to zero.

e,

int roll[2][4]={{1,1},{2,2,2}};

//first 2 elements of 1st row to 1 and 1st 3 elements of 2nd row to 2 and remaining are set to zerog

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