Object Oriented Programming - Value Types & Reference Types

Q3M1 – OOP C# Dudy Fathan Ali S.Kom

Value Types & Reference TypesQ3M1

Dudy Fathan Ali, S.Kom (DFA)2015

CEP - CCITFakultas Teknik Universitas Indonesia

Introduction


o The variables in a program are allocated memory at run time in the system.

o Variables are referred in two ways, value type and reference type.

o Value type variables contain data, whereas reference type variables hold the reference to the memory location where data is stored.

Describing Memory Allocation


The memory allocated to variables is referred to in two ways, value types and reference types.

- OOP C#, NIIT Courseware MMSv2.

int Num1 = 50;int Num2 = 100;

Example :

50

Value types are also called direct types because they contain data.

100

Num1

Num2

Memory Allocated for Value Type Variable





int Num1 = 50;int Num2 = Num1;Console.WriteLine(Num1);Console.WriteLine(Num2);

Another Example :

50

50

Num1

Num2







int Num1 = 50;int Num2 = Num1;Console.WriteLine(Num1);Num1++;Console.WriteLine(Num2);

Another Example :

Output:

5050

incrementing Num1 will have no effect on Num2





class Car{ public int Model; public void Display_Model() { Console.WriteLine (Model); }}

class Program{ static void Main (string[] args) { Car Ford = new Car (); Ford.Model = 10; Car Mercedes = Ford; Ford.Display_Model(); Mercedes.Display_Model (); }}

Memory Allocated for Reference Type Variable

****

Ford

****

Mercedes10

**** Output:

1010



class Car{ public int Model; public void Display_Model() { Console.WriteLine (Model); }}

class Program{ static void Main (string[] args) { Car Ford = new Car (); Ford.Model = 10; Car Mercedes = Ford; Ford.Display_Model(); Ford.Model++; Mercedes.Display_Model (); }}

Memory Allocated for Reference Type Variable

****

Ford

****

Mercedes10

****

11

Incrementing Form.Model will changing the value of Mercedes.Model.

Enumeration


Enumeration is a value type data type, it allows you to assign symbolic names to integral constants.


enum Days { Sat, Sun, Mon, Tue, Wed, Thu, Fri };

To declare an enumeration type called Days, where the values are restricted to thesymbolic names of the weekdays, use the following code:

Code :

Integral Constant

0 1 2 3 4 5 6

Symbolic Name

Sat Sun Mon Tue Wed Thu Fri

Representation :

Enumeration


class EnumTest{ enum Days { Sat, Sun, Mon, Tue, Wed, Thu, Fri }; static void Main(string[] args) { int First_Day = (int)Days.Sat; int Last_Day = (int)Days.Fri; Console.WriteLine(“Sat = ” + First_Day); Console.WriteLine(“Fri = ” + Last_Day); Console.ReadLine(); }}

Integral Constant

0 1 2 3 4 5 6

Symbolic Name

Sat Sun Mon Tue Wed Thu Fri

Full Code :

Representation :

Output:

Sat = 0Fri = 6

Array


An array is a collection of values of the same data type. Array elements are accessed using a single name and an index number representing the position of the element within the array. Array is a reference type data type.

Array Structure

Array


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 :

<data type>[] <array name>

Code Structure :

String[] DaftarNama;

Example Code :

String[] DaftarNama = new String[2];DaftarNama[0] = “Bambang”;DaftarNama[1] = “Suprapto”;

Initializing and Assigning Value :

Array


string[] n1 = new string[5];Data Dalam Memori :

Data Dalam Array :

i=0

Indeks di mulai dari 0

Assigning Value

Array


string[] n1 = new string[5];Data Dalam Memori :

Data Dalam Array :

i=0Masuk Nilai “1”

Assigning Value

Array


1

string[] n1 = new string[5];

n1[0] = “1”;

Data Dalam Memori :

i=0

a

1 a

Assigning Value

Array


1


n1[0] = “1”;

Data Dalam Memori :

i=0

a

1 a

Masuk Nilai “5”

a

Assigning Value

Array


1 5


n1[0] = “1”;

n1[1] = “5”;

Data Dalam Memori :

i=0

a

1 a

i=1

b

5 b

a

b

Assigning Value

Array


1 5


n1[0] = “1”;

n1[1] = “5”;

Data Dalam Memori :

i=0

a

1 a

i=1

b

5 b

Masuk Nilai “7”

a

b

Assigning Value

Array


1 5 7


n1[0] = “1”;

n1[1] = “5”;

n1[2] = “7”;

Data Dalam Memori :

i=0

a

1 a

i=1

b

5 b

c

i=2

7 c

a

b

c

Assigning Value

Array


1 5 7


n1[0] = “1”;

n1[1] = “5”;

n1[2] = “7”;

Data Dalam Memori :

i=0

a

1 a

i=1

b

5 b

c

i=2

7 c

a

b

c

Masuk Nilai “3”

Assigning Value

Array


1 5 7 3


n1[0] = “1”;

n1[1] = “5”;

n1[2] = “7”;

n1[3] = “3”;

Data Dalam Memori :

i=0

a

1 a

i=1

b

5 b

c

i=2

7 c

a

b

c

i=3

d

d

3 d

Assigning Value

Array


1 5 7 3


n1[0] = “1”;

n1[1] = “5”;

n1[2] = “7”;

n1[3] = “3”;

Data Dalam Memori :

i=0

a

1 a

i=1

b

5 b

c

i=2

7 c

a

b

c

i=3

d

d

3 d

Masuk Nilai “9”

Assigning Value

Array


1 5 7 3 9


n1[0] = “1”;

n1[1] = “5”;

n1[2] = “7”;

n1[3] = “3”;

n1[4] = “9”;

Data Dalam Memori :

i=0

a

1 a

i=1

b

5 b

c

i=2

7 c

a

b

c

i=3

d

d

3 d

e

e

e9

i=4

Assigning Value

Array


1 5 7 3 9


n1[0] = “1”;

n1[1] = “5”;

n1[3] = “7”;

n1[4] = “3”;

n1[5] = “9”;

Data Dalam Memori :

i=0

a

1 a

i=1

b

5 b

c

i=2

7 c

a

b

c

i=3

d

d

3 d

e

e

e9

i=4Bisa diisi lagi?

Assigning Value

Array


1 5 7 3 9


n1[0] = “1”;

n1[1] = “5”;

n1[3] = “7”;

n1[4] = “3”;

n1[5] = “9”;

Data Dalam Memori :

i=0

a

1 a

i=1

b

5 b

c

i=2

7 c

a

b

c

i=3

d

d

3 d

e

e

e9

i=4

Tidak! Karena Array PENUH.

Assigning Value

Array


Display Array Value

string[] n1 = new string[5]n1[0] = 1;n1[1] = 5;n1[2] = 3;n1[3] = 8;n1[4] = 4;

int x,i;x = n1.length();i = 0;for(i=0;i<x;i++){ Console.WriteLine(n1[i]);}Console.ReadLine();

Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x

Tampil nilai “i”

1 5 3 8 4i=0 i=1 i=2 i=3 i=4

Tampil Di Layar :

x = 5

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4

Tampil Di Layar :

x = 5

i=0

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4

Tampil Di Layar :

x = 5

i=0 i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4

Tampil Di Layar :

x = 5

n[0] = 1i=0 i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4

Tampil Di Layar : 1

x = 5

n[0] = 1 Tampil “1”i=0 i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4

Tampil Di Layar : 1

n[0] = 1 Tampil “1” i = i+ 1i=0

x = 5

i < x

Y i yang baru = 1

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4

Tampil Di Layar : 1

x = 5

i=1 i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4

Tampil Di Layar : 1

x = 5

n[1] = 5i=1 i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4

Tampil Di Layar : 15

x = 5

n[1] = 5 Tampil “5”i=1 i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


n[1] = 5 Tampil “5” i = i+ 1i=1

x = 5

i < x

Y i yang baru = 2

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


x = 5

i=2 i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


x = 5

n[2] = 3i=2 i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


x = 5

n[2] = 3 Tampil “3”i=2 i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


n[2] = 3 Tampil “3” i = i+ 1i=2

x = 5

i < x

Y i yang baru = 3

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


x = 5

i=3 i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


x = 5

n[3] = 8i=3 i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


n[3] = 8 Tampil “8”i=3

x = 5

i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


n[4] = 4 Tampil “4” i = i+ 1i=3

x = 5

i < x

Y i yang baru = 4

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


i=4

x = 5

i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


n[4] = 4i=4

x = 5

i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


n[4] = 4 Tampil “4”i=4

x = 5

i < x

Y

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


n[4] = 4 Tampil “4” i = i+ 1i=4

x = 5

i < x

Y i yang baru = 5

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


i=5

x = 5

i < x

N

Array


Display Array Value



Data array

int x,i

i++

Y

N

next command

x = n1.lengthi = 0

i < x


1 5 3 8 4i=0 i=1 i=2 i=3 i=4


Data telah tampil semua

Array


Latihan Mandiri

1. Buatlah array untuk menyimpan sejumlah nama siswa (jumlah siswa berdasarkan inputan user)

2. Buatlah 2 array untuk menyimpan angka ganjil dan angka genap dari 0 – 20 dan

3. Jumlahkanlah isi dari array ganjil dan array genap4. Jumlahkanlah array ganjil dan genap dengan index yang sama

kemudian masukkan hasil penjumlahannya ke dalam array yang baru

5. Hasil dari ke empat latihan di atas harus bisa ditampilkan


Thank You!Dudy Fathan Ali S.Kom

[email protected]

Credits array content by : Yaddarabullah S.Kom M.Kom

mailto:[email protected]

Technology

Object Oriented Programming - Value Types & Reference Types