Linear Search

Linear search is used on a collection of items. It relies on the technique of traversing a list from start to end by exploring properties of all the elements that are found on the way.

For example, consider an array of integers of size $N$. You should find and print the position of all the elements with value $x$. Here, the linear search is based on the idea of matching each element from the beginning of the list to the end of the list with the integer $x$, and then printing the position of the element if the condition is `True'.

Implementation:

for(start to end of array)
{
    if (current_element equals to 5)  
    {
        print (current_index);
    }
}

For example, consider the following image:

If you want to determine the positions of the occurrence of the number $7$ in this array. To determine the positions, every element in the array from start to end, i.e., from index $1$ to index $10$ will be compared with number $7$, to check which element matches the number $7$.

Time Complexity:

The time complexity of the linear search is $O(N)$ because each element in an array is compared only once.