**Searching Algorithm.**

In an Array based on the type of search operation, these algorithms are generally classified into two categories: (1) Linear Search. (2) Binary Search.

##### (1) Linear Search :

In this, the list or array is traversed sequentially and every element is checked.

Code:

`**// code for linear Search**

```
#include<bits/stdc++.h>
using namespace std;
**// this function has argument as array and int which we need to search and if fount it returns its index else it returns -1.**
int linear_search(int arr[10],int x)
{
for(int i=0;i<10;i++)
{
if(arr[i]==x)
{
return i;
}
}
return -1;
}
int main()
{
int arr[10];
int x;
for(int i=0;i<10;i++)
{
cin>>arr[i];
}
cin>>x;
int ans=linear_search(arr,x);
cout<<ans;
return 0;
}`
```

Time Complexity: O(N). ,where N is the number of elements in the array/list

##### **Binary Search **:

Binary Search is defined as a searching algorithm used in a sorted array by repeatedly dividing the search interval in half. The idea of binary search is to use the information that the array is sorted and reduce the time complexity to O(log N).

**Algorithm :**
(1) Divide the search space into two halves by finding the middle index “mid”.
(2) finding the middle index "mid" in Binary Search Algorithm
(3) Finding the middle index “mid” in Binary Search Algorithm

Compare the middle element of the search space with the key. If the key is found at middle element, the process is terminated. If the key is not found at middle element, choose which half will be used as the next search space. If the key is smaller than the middle element, then the left side is used for next search. If the key is larger than the middle element, then the right side is used for next search. This process is continued until the key is found or the total search space is exhausted.

Code :

// C program to implement iterative Binary Search #include <stdio.h>

// An iterative binary search function. int binarySearch(int arr[], int l, int r, int x) { while (l <= r) { int m = l + (r - l) / 2;

```
// Check if x is present at mid
if (arr[m] == x)
return m;
// If x greater, ignore left half
if (arr[m] < x)
l = m + 1;
// If x is smaller, ignore right half
else
r = m - 1;
}
// If we reach here, then element was not present
return -1;
```

}

```
// Driver code
int main(void)
{
int arr[] = { 2, 3, 4, 10, 40 };
int n = sizeof(arr) / sizeof(arr[0]);
int x = 10;
int result = binarySearch(arr, 0, n - 1, x);
(result == -1) ? printf("Element is not present"
" in array")
: printf("Element is present at "
"index %d",
result);
return 0;
}
```

to practice the questions : https://practice.geeksforgeeks.org/problems/binary-search-1587115620/1?utm_source=gfg&utm_medium=article&utm_campaign=bottom_sticky_on_article