Pascal Syntax

Pascal is similar to other high-level languages but different than most C-like languages. All the familiar contructs are present. The biggest way in which Pascal differs from many other high-level languages is that Pascal is not case sensitive for language keywords, functions, procedures, and variables. MyVar is the same variable as myVar, myvar, and MYVAR.

For readability purposes, example code in this documentation will be shown in mixed-case form.

Like C, all Pascal statements must be terminated with a semi-colon. Almost all Pascal blocks are also terminated with a semi-colon except the top-level PROGRAM block, which is terminated with a period.

Hello World

In observance of the long-standing tradition in programming documentation, following is a bare-bones example of a Pascal program.

PROGRAM helloworld(output);
BEGIN
    writeln('Hello, world!');
END.

Notice the period after the END keyword.

Because of Pascal's case-insensitivity, the above example could also be written as:

Program HelloWorld(output);
Begin
    Writeln('Hello, world!');
End.

Structure of a Pascal Program

Every Pascal program starts with a Program statement followed by the name of the program and the program's inputs in parenthesis and a semi-colon.

The Program statement is followed by optional sections defining constant values, type declarations, variable declarations, function declarations, procedure declarations, and finally the main program block.

This is how a Pascal program might look with all these structures.

Program NameOfProgram(output);

Type
(* Type declarations *)

Const
(* Constant value declarations *)

Var
(* Global variable declarations *)

Function SampleFunctionName
Var
   (* Local Variable Declarations *)
Begin
   (* Function Code *)
End;

Procedure SampleProcedureName
Var
   (* Local Variable Declarations *)
Begin
   (* Procedure Code *)
End;

Begin
   (* Main program block code *)
End.