Write a program to search a number by using binary search method.

The main techniques are given below:

$$ Case $1$: If the key is less than the middle element, recursively search for the key in the

first half of the array.

$$ Case $2$: If the key is equal to the middle element, the search ends with a match.

$$ Case $3$: If the key is greater than the middle element, recursively search for the key in the

second half of the array.