The basic syntax for a variable declaration is
var identifierList: type;
where identifierList is a comma-delimited list of valid identifiers and type is any valid type. For example,
var I: Integer;
declares a variable I of type Integer, while
var X, Y: Real;
declares two variables—X and Y—of type Real.
Consecutive variable declarations do not have to repeat the reserved word var:
var
X, Y, Z: Double;
I, J, K: Integer;
Digit: 0..9;
Okay: Boolean;
Variables declared within a procedure or function are sometimes called local, while other variables are called global. Global variables can be initialized at the same time they are declared, using the syntax
var identifier: type = constantExpression;
where constantExpression is any constant expression representing a value of type type. Thus the declaration
var I: Integer = 7;
is equivalent to the declaration and statement
var I: Integer;
...
I := 7;
Multiple variable declarations (such as var X, Y, Z: Real;) cannot include initializations, nor can declarations of variant and file-type variables.
If you don't explicitly initialize a global variable, the compiler initializes it to 0. Local variables, in contrast, cannot be initialized in their declarations and contain random data until a value is assigned to them.