Transcript Pascal Programming

Pascal Programming
Written by Leung King Yung
Simple Program 1
begin
end.
Simple Program 2
program Test;
uses wincrt;
begin
writeln(‘Good Afternoon!’);
end.
Simple Program 2
Results:
Reserverd Words
These are the common reserved
words of pascal program. You
cannot use this as a variable name.
begin end program var string
if then else for to downto
while do repeat until
procedure function in
Program Title
program Test; {This is the program
title(you can omit it)}
begin
{Main Body}
end.
Data type
These are the common data type of pascal program.
Type
Explanation
Additional
explanation
integer Whole numbers
Example
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 variable
program Test;
var i : integer;
var s : string;
var c : char;
var b : boolean;
var r : real;
begin
{Main Body}
end.
Declaring variable
program Test;
Uses wincrt;
var i : integer;
s : string;
c : char;
b : boolean;
r : real;
Begin
I := 0;
Writeln(i);
end.
Using Library
program 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 Variables
program Test;
uses wincrt;
var i : integer;
Begin
Readln(i);
writeln(i);
end.
Using Variables
Results:
Using Variables
program Test;
uses wincrt;
var i : integer;
j : integer;
begin
i := 7;
j := 3;
i := i + j;
writeln(i);
end.
Using Variables
Results:
Comparing VB with Pascal
VB: Dim i as integer
Pascal: var i : integer;
VB: i = 10
Pascal: i := 10;
VB: ‘comment
Pascal: {Comment}/(*Comment*)
Comparing VB with Pascal
VB:
Dim j as integer
j = 10
If j = 10 then
print “J = 10”
Else
print “J <> 10”
End If
Comparing VB with Pascal
Pascal:
Uses wincrt;
var j : integer;
begin
j := 10;
if j = 10 then
writeln(‘J = 10’)
else
writeln(‘J <> 10’);
End.
IF…THEN…ELSE
program Test;
var j : integer;
begin
j := 10;
if j = 10 then
writeln(‘J = 10’) {*** No “;”}
else
writeln(‘J <> 10’);
writeln(‘End of program’);
end;
IF…THEN…ELSE
The whole
If-Phrase
program Test;
var j : integer;
begin
j := 10;
if j = 10 then
writeln(‘J = 10’)
else
writeln(‘J <> 10’);
writeln(‘End of program’);
end;
Complicated IF…THEN…ELSE
if 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…ELSE
if 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.