The if statement allows conditional execution of a statement or a conditional
choice of two statements, executing one or the other but not both.
IfThenStatement:
if (Expression)Statement IfThenElseStatement:
if (Expression)StatementNoShortIfelseStatement IfThenElseStatementNoShortIf:
if (Expression)StatementNoShortIfelseStatementNoShortIf
The Expression must have type boolean, or a compile-time error occurs.