Write a function in a C++ program that does the following tasks:
a. Counting the number of characters in a string and printing it backward
b. Function to count the number of words in a string
c. Function to find the length of a string
d. Function to copy the contents of string S2 to S1
e. Function to compare strings STR1 to STR2.
f. Function to concatenate the contents of string S2 to S1
g. To reverse the contents of string S and store it in string Rev
h. Function to change the case of string S to uppercase
i. Function to change the case of string S to lower case