This is not an active exam. The following function protoptypes must be implemented $($You may add other functions if you want$)1)$char most$\_$occuring$\_$character $($ char $*$ str$)$;$//$this function retuns the char that appears the most. It returns $-1$ if that doesnt apply $2)$void count$\_$low$\_$up$\_$digit $($ char $*$ str$,$ int$*$ lower, int$*$ upper $,$ int $*$digit$)$;$//$this function counts how many lower, upper and digit characters. $3)$char $*$ Up$\_$letters $($ char $*$ str$)$;$//$This function returns the sorted upper case letters as shown in sample runs