05 iec t1s1 oops session 07

8/14/2019 05 Iec t1s1 Oops Session 07

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Slide 1 of 32Session 7Ver. 1.0

Object-Oriented Programming Using C#

In this session, you will learn to:

Describe memory allocation

Use structure

Use enumerations

Implement arraysUse collections

Objectives


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The memory allocated to variables is referred to in the

following ways:

Value types: Contains data. Built-in data types, such as int,

char, and float are value types.

Reference types: Contains address referring to a block of

memory. Data types, such as string and class are reference

types.

Let us understand the concept of memory allocation in

detail.

Describing Memory Allocation


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Describing Memory Allocation (Contd.)

int Num1;

Num1=50;Initialization

Initializing Num2 with Num1

int Num2;

Num2=Num1;

Variable Declaration

Value Type:

Variable Declaration 50

50

Both Num1 and Num2 Contain 50

Num1

Num2


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Value Type (Contd.):

Num1=60;

Num1

60

Num2

50

The Value of Num2 Remains Unaffected

New Value Assigned to Num1


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Car Suzuki= new Car();

Suzuki.Model=10;

Object of Class Car()

Member Variable of Class Car()

Initialization

Initializing Mercedes with Suzuki

Object of Class Car()Car Mercedes;

Mercedes=Suzuki;


Reference Type:


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Suzuki

Mercedes

***

***

10

Referring to Memory

Location Where the Data

is Stored

Referring to Memory

Location Where the Data

is Stored


Reference Type (Contd.):


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A structure is a value type data type.

When you want a single variable to hold related data of

various data types, you can create a structure.

To create a structure you use the struct keyword.

The following code shows the example of a declaring astructure names Bill_Details:

struct Bill_Details

{ public string inv_No; // Invoice Number

string ord_Dt; // Order Date

string custName; // Customer name

Using Structure




public string product; // Product Name

public double cost; // Cost of the product

public double due_Amt; // Total amount due

}

Using Structure (Contd.)




Enumeration is a value type data type.

Enumeration contains its own values and cannot inherit or

pass inheritance.

Enumerators allows you to assign symbolic names to

integral constants.To enumerate, you can use the enum keyword.

Using Enumeration


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After declaring the enumeration type, you can use the

enumeration type in the same manner as any other data

type:

int First_Day = (int)Days.Sat;

int Last_Day = (int)Days.Fri;

Implementing Enumerations




Implementing Arrays

An array is a collection of values of the same data type.

The following figure shows the array structure in the

systems memory.

Index

Value 0

Index

Value 6




Declaring an Array

An array needs to be declared before it can be used in a

program.

You can declare an array by using the following statement:

datatype[] Arrayname;

Let us understand the explanation of the various elements

of the array declaration through an example.




Declaring an Array (Contd.)

int[ ] Score; Datatype

Is used to specify the

data type for the

elements





int[ ] Score; [ ]


rank of the array





int[ ] Score; Arrayname


name of the array using

which the elements of the

array will be initialized and

manipulated




In C#, you can initialize the array variable and can assign

values to the array elements. In addition, you can copy the

array variable to another variable.

During initialization, you need to use the new keyword to

create an instance of the array. In addition, the size of the

array is also specified while it is initialized.

The following is an example of array initialization:

int[] Score; // Array declaration

Score = new int[10]; //Array Instance

Initializing and Assigning Values to Array


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When an array is initialized, you can access the element

values and manipulate them.

The foreach loop is specially used for manipulating arrays.

The following is the syntax of the foreach loop:

foreach (type identifier in expression){

//statements

}

Manipulating Array Elements




The following is the example offoreach loop:

int[] Numbers = { 4, 3, 2, 1, 0, -1, -2, 9, 5 };

Console.WriteLine("The Contents of an Array

is:");

foreach (int K in Numbers)

{

Console.WriteLine("{0} \t",K);

}

Manipulating Array Elements (Contd.)




While declaring a method if you are not sure about the

number of arguments passed as a parameter, you can use

the param array.

The following is the example ofparam array:

public int Adding_ArrayElement(params int[] List)

{

int Total = 0;

foreach ( int I in List )

{

Total += I;}

return Total;

}

Manipulating Array Elements (Contd.)




Demo: Matrix Subtraction UsingArrays

Problem Statement:

David, a student of California University, is currently pursuing

mathematics. He is working on a project named Matrix

Subtraction. He needs to perform the following tasks for his

project:

Accept data in two Arrays.

Perform the subtraction operation.

Verify the value of subtraction.

Help David to create the C# program using Visual Studio IDE.


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Solution:

To solve the preceding problem, David needs to perform the

following tasks:

1. Create a console-based application for Matrix Subtraction.

2. Build and execute an application.

Demo: Matrix Subtraction Using Arrays (Contd.)


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Multidimensional Arrays

The rank value of the array is also known as the dimension

of the array.

The array can be single dimensional or multidimensional.

Single dimensional array stores data in a row.

Multidimensional array stores data using differentdimensions.

The following figure is a graphical representation of values

stored in a single dimensional array and a multidimensional

array.int [] Num; int[,] Num;

0

0 1 2 3 4 1

0 1 2 3 4


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Multidimensional Arrays (Contd.)

The Array class is the base class for all the arrays in C#.

The Array class provides properties and methods to work

with arrays.

Properties: The following table explains some of the most

commonly used properties of the Array class.

Properties Explanation

Length Returns the total number of items in all the dimensions of anarray

Rank Returns the total number of items in all the dimensions of anarray

IsFixedSize Return a value indicating if an array has a fixed size or not

IsReadOnly Returns a value indicating if an array is read-only or not


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Multidimensional Arrays (Contd.)

Methods: The following table explains some of the most

commonly used methods of the Array class.

Properties Explanation

Sort Performs sort operation on an array passed to it as a parameter

Clear Removes all items of an array and sets a range of items in thearray to 0

GetLength Returns the number of items in an Array

GetValue Returns the value of the specified item in an Array

IndexOf Returns the index of the first occurrence of a value in aone-dimensional Array or in a portion of the Array


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Using Collections

Arrays are used to collect the elements of same data type.

The .NET Framework provides several classes that also

collect elements in specialized ways. Theses classes are

the Collection classes, and are declared in the

System.Collections namespace and sub-namespaces.


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Using Collections (Contd.)

The collection classes accept, hold, and return their

elements as items.

The element type of collection class is an object. Object is a

reference type.

The following figure shows the storage of values in array oftype int:STACK HEAP

9 7 3 2

Array

@

int [] array= {9, 7, 3, 2};


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The action which automatically converts the value type to

the reference type, is known as boxing.

The following figure shows the boxing technique.

STACK HEAP

@ @ @ @

Array

@

int [] array= {9, 7, 3, 2};

7 2

39


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When you want to access the elements of an array through

its index value location in an array, use an ArrayList

class.

The following table describes the use of various methods of

an ArrayList class.

Method Use

Add Adds an object to the end of the ArrayList

Remove Removes the element at the first occurrence of a specific object from theArrayList

Clear Removes all the elements from the ArrayList

Insert Inserts an element into the ArrayList at the specified indexTrimToSize Sets the capacity to the actual number of elements in the ArrayList

Sort Sorts the elements in the ArrayList

Reverse Reverses the element in the ArrayList


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In this session, you learned that:

Memory allocated to variables are of two types, value type and

reference type.

Value-types are the simplest types in C#. Variables of value

types directly contain their data in the variable.

Reference-types variables contain only a reference to data. Thedata is stored in a separate memory area.

A value type variable holds its value in the stack.

A reference type variable holds a reference to an object in the

heap.

To hold related data of various data type in single variable,structures are used.

C# provides the features ofenum to create user defined data

types with numbers as an index value to access them.

An array is a collection of values of the same data type.

Summary


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The foreach statement interprets the common loop process

and removes the need for you to check the array size.

Param arrays are used in the methods with parameter list

when the total number of parameters is not known.

The .NET Framework provides several classes that also collect

elements together in other specialized ways. These are theCollection classes, and they live in the System

namespace.

ArrayList is useful when you want to manipulate the values

in an array easily.

Summary (Contd.)

05 iec t1s1 oops session 07

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