Pascal Programming

Written by Leung King Yung

Simple Program 1

begin

end.

Simple Program 2program Test;

uses wincrt;

begin

writeln(‘Good Afternoon!’);

end.

Simple Program 2Results:

Reserverd Words

begin end program var string if then else for to downto while do repeat until procedure function in

These are the common reserved words of pascal program. You

cannot use this as a variable name.

Program Title

program Test; {This is the program title(you can omit it)}

begin

{Main Body}

end.

Data typeThese are the common data type of pascal program.

Type Explanation Additional

explanation Example

integer Whole numbers 3, 104, 0, -9

string String variable (Text) 'Hello World', '456,4'

char Character (One character) 'b', 'A', '7'

boolean Boolean variable

Can only be True or False

True, False

real Real numbers (Floating point numbers)

4.0, -0.08, 48.6, 2.0E4

Declaring variableprogram Test;

var i : integer;

var s : string;

var c : char;

var b : boolean;

var r : real;

begin

{Main Body}

end.

Declaring variableprogram Test; Uses wincrt;var i : integer; s : string; c : char; b : boolean; r : real; BeginI := 0;Writeln(i);end.

Using Libraryprogram Test;

uses wincrt; {Wincrt is a common library in turbo pascal for i/o manipulations wincrt.tpu}

var i : integer;

begin

{Main Body}

end.

Using Variablesprogram Test;

uses wincrt;var i : integer; Begin

Readln(i);

writeln(i);

end.

Using VariablesResults:

Using Variablesprogram Test;

uses wincrt;var i : integer; j : integer;begini := 7; j := 3;i := i + j;writeln(i);

end.

Using VariablesResults:

Comparing VB with PascalVB: Dim i as integer

Pascal: var i : integer;

VB: i = 10

Pascal: i := 10;

VB: ‘comment

Pascal: {Comment}/(*Comment*)

Comparing VB with PascalVB:

Dim j as integer

j = 10

If j = 10 then

print “J = 10”

Else

print “J <> 10”

End If

Comparing VB with PascalPascal:

Uses wincrt;

var j : integer;

begin

j := 10;

if j = 10 then

writeln(‘J = 10’)

else

writeln(‘J <> 10’);

End.

IF…THEN…ELSEprogram Test;var j : integer;beginj := 10;if j = 10 thenwriteln(‘J = 10’) {*** No “;”}

elsewriteln(‘J <> 10’);

writeln(‘End of program’);end;

IF…THEN…ELSEprogram Test;var j : integer;beginj := 10;if j = 10 thenwriteln(‘J = 10’)

elsewriteln(‘J <> 10’);

writeln(‘End of program’);end;

The whole If-Phrase

Complicated IF…THEN…ELSEif i = 10 then

if j = 10 then

writeln(‘i = 10 and j = 10’)

else

writeln(‘i = 10 and j <> 10’)

else

writeln(‘i <> 10 and j <> 10’);

Correct Program

Complicated IF…THEN…ELSEif i = 10 then

if j = 10 then

writeln(‘i = 10 and j = 10’)

else

writeln(‘i = 10 and j <> 10’);

else

writeln(‘i <> 10 and j <> 10’); Wrong semicolon

(Syntax Error)

Comment

begin

{This is a comment}

(* This is also a comment*)

end.