# Linear Search Algorithm and Implementation in C

Published on August 3, 2022 By Safa Mulani
Developer and author at DigitalOcean. While we believe that this content benefits our community, we have not yet thoroughly reviewed it. If you have any suggestions for improvements, please let us know by clicking the “report an issue“ button at the bottom of the tutorial.

Linear Search is basically a sequential search algorithm.

In this algorithm, the key element is searched in the given input array in sequential order.

If the key element is found in the input array, it returns the element.

## Linear Search Algorithm

Linear_Search ( Array X, Value i)

• Set j to 1
• Then, increment j by 1 i.e. j = j+1
• Go back to step 2
• Display the element i which is found at particular index i, then jump to step 8
• Exit/End

``````procedure LINEAR_SEARCH (array, key)

for each item in the array
if match element == key
return element's index
end if
end for

end procedure
``````

## Implementation of Linear Search in C

• Initially, we need to mention or accept the element to be searched from the user.
• Then, we create a for loop and start searching for the element in a sequential fashion.
• As soon as the compiler encounters a match i.e. array[element] == key value, return the element along with its position in the array.
• If no values are found that match the input, it returns -1.
``````#include <stdio.h>

int LINEAR_SEARCH(int inp_arr[], int size, int val)
{

for (int i = 0; i < size; i++)
if (inp_arr[i] == val)
return i;
return -1;
}

int main(void)
{
int arr[] = { 10, 20, 30, 40, 50, 100, 0 };
int key = 100;
int size = 10;
int res = LINEAR_SEARCH(arr, size, key);
if (res == -1)
else
printf("Item is present at index %d", res);

return 0;
}
``````

Output:

``````Item is present at index 5
``````

The best-case complexity is O(1) if the element is found in the first iteration of the loop.

The worst-case time complexity is O(n), if the search element is found at the end of the array, provided the size of the array is n.

## Conclusion

Thus, in this article, we have understood and implemented Linear Search Algorithm. Developer and author at DigitalOcean.

#### Still looking for an answer?

not understand why size is has a 10. don’t be 7?