If c is a lowercase character, the expression c - 'a' + 'A' produces the uppercase equivalent of c, assuming an ASCII character set. Write a function called uppercase() that converts all lowercase characters in a string into their uppercase equivalents. Note that the uppercase?) function only changes the lowercase characters to the uppercase equivalents, but all other characters, such as digits, special characters, or uppercase character, should be unchanged. Also, write a whole program to do following things: 1) read a string from user's input by keyboard. 2) Assume the input is less than 80 characters. 3) pass the input string to the uppercase() function, then print out changed string which has all the characters 4) Use "void uppercase(char *str)" or "void uppercase(char str[])" as the function prototype