C++ question

2. Write a recursive binarySearch function for an array of strings (already sorted), that returns the indexes of all the strings whose first letter is A / "a". For example, for anArray = {Arrow", "art, box, curve, line"}, the search result should show: indexes = {0, 1}. Notes: You should set the target letter to be a variable, so thtwe can use your function to search strings starting with any given letter withing a-z / A- Z