C Function to Extract Substring from Middle of String

This function takes in a destination character pointer (des), an integer size, a source character pointer (src), an integer first, and an integer count. It is supposed to return a character pointer that points to the middle of the source string, starting from the position specified by the 'first' integer and grabbing a number of characters specified by the 'count' integer. However, the function currently does not have any implementation and simply returns the destination character pointer without any modifications.