Language: C99

Write a function void num_of_duplicates(void) which reads non-whitespace printable ASCII characters as input from the keyboard and prints the number of times a duplicate character exists in the array a. As an example, if the input consisted of ten copies of the character a, five copies of the character band one copy of the character c in any order, the function should print 2 as the characters a and b are duplicated characters and c is not.