Behavior of the main function
The main function in Listing 3 declares and initializes two local variables named a and b.
(I will provide an explanation of the different kinds of variables, including local variables, in a future lesson. For now, just think of a local variable as a pigeonhole in memory where a value is stored.)
The types of the two variables are int and double respectively.
(I will also provide more information about the types of variables such as int and double in a future lesson. For now, a variable of type int can contain whole numbers only, such as 9 or 3642. A variable of type double can contain values with fractional parts, such as 1.333.)