Object Oriented Programming Arrays Chapter 5, Thesis of Object Oriented Programming

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Lecture 5: Arrays

Arrays

• A data structure which stores fixed size collection of

elements of the same type.

• Once an array is created, its size is fixed.
• An array is used to store a collection of data of the same

type.

• Instead of declaring individual variables such as

number0, number1 ….number99.. We can declare one

array variable called numbers of size 100.

• We can then access all the number using an index. 6/13/2018 Object Oriented Programming

Indexing Arrays

• Access to array members is done through indexes.
• Indexing starts at 0.
• Example:

int [] myarray=new int[5];

myarray[0]=10; myarray[1]=20; myarray[2]=30; myarray[3]=40; myarray[4]=50; 6/13/2018 Object Oriented Programming Index Value myarray[0] 10 myarray[1] 20 myarray[2] 30 myarray[3] 40 myarray[4] 50

Example

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Examples of processing arrays:

1. Initializing arrays with input values

Scanner input=new Scanner(System.in);

int [] myarray=new int[5];

System.out.println("Enter 5 integers");

for(int i=0; i<5; i++)

myarray[i]=input.nextInt();

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2. Displaying arrays

int [] myarray=new int[5]; for(int i=0;i<5;i++) { System.out.println(myarray[i]) } 6/13/2018 Object Oriented Programming

length

• How can we get the length of an array?
• Using the .length attribute
• Example myarray.length will return the size of my array We can use this .length attribute in out for loops int [] myarray=new int[5]; double total=0; for(int i=0;i<myarray.length;i++) { total=total+myarray[i] } 6/13/2018 Object Oriented Programming

for(int i=0;i<5;i++)

Passing Arrays to methods

public static void printArray(int [] myarray)

for (int i=0;i<myarray.length;i++)

System.out.println(myarray[i]);

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Array of Objects

• Student [] mystudent=new Student[5]
• mystudent[0]=new Student() 6/13/2018 Object Oriented Programming

Exercise

• Write a program to find the maximum and minimum values from an int array 6/13/2018 Object Oriented Programming