Given an unsorted array and an element x, search x in the given array. Write recursive C code for this. If the element is not present, return -1. 
The idea is to compare x with the last element in arr[]. If the element is found at the last position, return it. Else recur searchElement() for remaining array and element x. 

We iterate through the array from the end by decrementing the size variable and recursively calling the function searchElement(). If the size variable becomes less than zero it means the element is not present in the array and we return -1. If a match is found, we return the size variable which is the index of the found element. This process is repeated until a value is returned to main().

Recursive program to linearly search an element in a given array  : https://www.geeksforgeeks.org/recursive-c-program-linearly-search-element-given-array/