1、In the function declaration,the argument identifiers are optional. In the definitions,they are required.
2、A #include may name a file in two ways:in angle brackets(<>) or in double quotes.
3、The operator << means "send to".
4、All of the Standard C++ libraries are wrapped in a single namespace, which is std(for "standard").
5、In C++,main() always has return type of int.
6、C and C++ are free form languages. The compiler ignores newlines and white spaces,so statements are delimited by semicolons.