Arrays.pptx

Arrays
 What are arrays?
 Types of Arrays
 Single dimensional arrays
 Searching an element
 Linear Search
 Binary Search
 Sorting an array
 --Bubble Sort
 ---Selection Sort
 Double dimensional arrays
 --Add/subtract row/column wise
 --Adding diagonal elements

With and without an array
• Think of an array as a "box" drawn in memory with a series of subdivisions,
called elements, to store the data. The box below could represent an array
of 10 integers.
• While this array contains only 10 elements, arrays are traditionally used to
handle large amounts of data. It is important to remember that all of the
elements in an array must contain the same type of data.
• Let's consider a programming situation "with" and "without" the use of an
array:
7 6 5 8 3 9 2 6 10 2

• An array is a container object that holds a fixed number of
values of a single type.
• The length of an array is established when the array is
created. After creation, its length is fixed.
• Arrays are used to store multiple values in a single
variable, instead of declaring separate variables for each
value. To declare an array, define the variable type with
square brackets:
• String[] cars;

• Suppose you have to calculate the average marks of 4
subjects:
• Suppose you have to find the average marks obtained by
50 students:
• Ans: Loops
• But

DECLARING ARRAYS
Declaration of an integer array of
10 elements
Declare a string array of 4 elements:

double a[]= new double[4];
What is the length of the array?
4.1 2.2 2.25 1.89
What is the value of a[2]?
How will you access the 2nd
element?
What is the output of the
following?
S.o.pln(a[4]);

• WAP to initialize a String array with 5 names and display
the 1st and last name.
• WAP to accept marks in 10 subjects and display them.

• WAP to accept the names & marks of 6 students in your
class as floating point decimals. Display the name and
marks of the student who has got the highest marks.

Searching an Element in an array
• Binary Search-
• Linear Search- It is the simplest way of searching an
element in an array.
• Algorithm:
Step 1: Traverse the array
Step 2: Match the key element with array element
Step 3: If key element is found, return the index position
of the array element
Step 4: If key element is not found, return -1

Linear Search
Problem: Given an array arr[] of n elements, write a function to search a given element x in arr[].
Examples :
Input : arr[] = {10, 20, 80, 30, 60, 50, 110, 100, 130, 170}
x = 110;
Output : 6
Element x is present at index 6
Input : arr[] = {10, 20, 80, 30, 60, 50, 110, 100, 130, 170}
x = 175;
Output : -1
Element x is not present in arr[].

• A simple approach is to do linear
search, i.e
• Start from the leftmost element of
arr[] and one by one compare x
with each element of arr[]
• If x matches with an element, return
the index.
• If x doesn’t match with any of
elements, return -1.

import java.util.Scanner;
class LinearSearch
{
public static void main(String args[])
{
int c, n, search, array[];
Scanner in = new Scanner(System.in);
System.out.println("Enter number of elements");
n = in.nextInt();
array = new int[n];

System.out.println("Enter " + n + " integers");
for (c = 0; c < n; c++)
array[c] = in.nextInt();
System.out.println("Enter value to find");
search = in.nextInt();
for (c = 0; c < n; c++)
{
if (array[c] == search) /* Searching element is present */ { System.out.println(search
+ " is present at location " + (c + 1) + ".");
break;
}
}
if (c == n) /* Element to search isn't present */
System.out.println(search + " isn't present in array.");
}
}

• WAP to accept the names of the seven wonders of the
world and its ranking in an array. Accept a name from the
user and check whether the name of the wonder is
present or not. If it is present display- for e.g.-
”Great_Pyramid_at_Giza is at 1st position”.
• Display appropriate messages if the name is not present.

Binary Search
• Binary search is used to
search a key element from
multiple elements. Binary
search is faster than linear
search.
• In case of binary search,
array elements must be in
ascending order.

Example of Binary Search
Consider a sorted array of 10 integers as given below,

import java.util.Scanner;
class BinarySearch
{
public static void main(String args[])
{
int c, n, search, array[];
Scanner in = new Scanner(System.in);
System.out.println("Enter number of elements");
n = in.nextInt();
array = new int[n];

import java.util.*;
class StringEven
{
public static void main()
{
Scanner sc =new Scanner(System.in);
String s[]=new String[10];
System.out.println("Enter the Strings");
for(int i=0;i<s.length;i++)
{
s[i]=sc.next();
}
System.out.println("Even letter Strings");
for(int i=0;i<10;i++)
{
if((s[i].length())%2==0)
System.out.println(s[i]);
}
}}

6 2 4 9 1 3
no. of elements =6

• Question 1
• Write a program in Java to store 20 numbers (even and
odd numbers) in a Single Dimensional Array (SDA).
Calculate and display the sum of all even numbers and all
odd numbers separately.
• Question 2
• Write a program in Java to store 20 temperatures in °F
in a Single Dimensional Array (SDA) and display all the
temperatures after converting them into °C.
• Hint: (c/5) = (f - 32) / 9

• Question 3
• Write a program in Java to store 10 numbers (including
positive and negative numbers) in a Single Dimensional
Array (SDA). Display all the negative numbers followed by
the positive numbers without changing the order of the
numbers.
• Sample Input:
• n[0] n[1] n[2] n[3] n[4] n[5] n[6] n[7] n[8] n[9]
• 15 21 -32 -41 54 61 71 -19 -44 52
• Sample Output: -32, -41, -19, 44, 15, 21, 54, 61, 71, 52

Question 4
• Write a program to accept the year of graduation from
school as an integer value from the user. Using the linear
search technique on the sorted array of integers given
below, output the message "Record exists" if the value
input is located in the array. If not, output the message
"Record does not exist".
• Sample Input:
• n[0] n[1] n[2] n[3] n[4] n[5] n[6] n[7] n[8] n[9]
• 1982 198719931996199920032006200720092010

Question 5
• Write a program to read the data, calculate and display
the following:
• (a) Average marks obtained by each student.
• (b) Print the roll number and the average marks of the
students whose average is above. 80.
• (c) Print the roll number and the average marks of the
students whose average is below 40.

Arrays.pptx

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Arrays.pptx