what does linear search do code example

Example: linear search

#include <bits/stdc++.h>

using namespace std; 

int search(int arr[], int n, int key) 
{ 
    int i; 
    for (i = 0; i < n; i++) 
        if (arr[i] == key) 
            return i; 
    return -1; 
} 

int main() 
{ 
    int arr[] = { 99,4,3,8,1 }; 
    int key = 8; 
    int n = sizeof(arr) / sizeof(arr[0]); 

    int result = search(arr, n, key); 
    (result == -1) 
        ? cout << "Element is not present in array"
        : cout << "Element is present at index " << result; 

    return 0; 
}