Searching - Linear search

Searching

Computer systems are often used to store large amounts of data from which individual records must be retrieved according to some search criterion. Thus the efficient storage of data to facilitate fast searching is an important issue. In this section, we shall investigate the performance of some searching algorithms and the data structures which they use.

Linear search

A linear search is the most basic of search algorithm you can have. A linear search sequentially moves through your collection (or data structure) looking for a matching value.

1. Implementation

#include<iostream>

using namespace std;

int main() {

cout<<"Enter The Size Of Array: "; int size;

cin>>size;

int array[size], key,i;

// Taking Input In Array

for(int j=0;j<size;j++){

cout<<"Enter "<<j<<" Element: ";

cin>>array[j];

}

//Your Entered Array Is

for(int a=0;a<size;a++){

cout<<"array[ "<<a<<" ] = ";

cout<<array[a]<<endl;

}

cout<<"Enter Key To Search in Array";

cin>>key;

for(i=0;i<size;i++){

if(key==array[i]){

cout<<"Key Found At Index Number : "<<i<<endl;

break;

}

}

if(i != size){

cout<<"KEY FOUND at index :  "<<i;

}

else{

cout<<"KEY NOT FOUND in Array  ";

}

return 0;

}

Image View Of Code:

Code Logic Explanation:

·        To Make Logic First We Think That We Have To Traverse Whole Array Form Start To End So we Decide To Use a Loop

·        First for Loop Taking Input in Array Element By Element Second Displaying Entered Elements

·        Third for Loop Which is Main For Loop Having an if Condition Which Checks Every

Array Element with Key

·        If an Element Matches With Key if Condition Becomes True and Loop Terminates

With Break Statement

·        Then If Condition Outside Loop Which Will Become True Because Loop Variable 'i' not Equal to Size Of Array

·        If Element Not Found In Array Than Loop Will Run Complete And If Condition Will

Not True Because in This Case Loop Will Run Complete And After Termination

Variable 'i' Will be Equal to Size Variable

Running The Code With Sample Input

Let size=5;

Array Elements are

1

2

3

4

5

Key is equal to 4

3rd for loop comparisons

i=0

if(1==4) false

i=1

if(2==4) false

i=2

if(3==4) false

i=3

if(4==4) True break for loop

Output:

Key Found At Index Number : 3