After you fix everything %51 told you, the last line in main() ("Operater()") is missing a semicolon, you're assigning an undefined variable called "A" to Operater (it doesn't sound like such a good idea to have a variable with the same name as a function, by the way), not the character 'A'.
That seems about it. If you're calling the compiler directly from command line, you may have mistyped something. That's the first time I've seen that error in three years.