This document discusses Pascal programming language concepts like procedures, functions, variables, and built-in functions. It explains that procedures and functions are types of subprograms that can take parameters. Procedures do not return a value while functions return a single value. It also discusses global and local variables as well as function and procedure signatures, prototypes, and how to declare and call them.

1. Pascal Programming Language
Omar ElSabek & Fayez Ghazzawi
IT Engineering
3th year – UNKNOWN Department

2. •Quiet!!!!!!!!!!
•Pay the fine! :P :D
•Being late!
•Talking!

3. •Procedures and Functions
• The most important material
• which are very important and you
should keep on practicing more
often.

4. • Pascal provides two kinds of subprograms:
•Functions : these subprograms return a single value.
•Procedures : these subprograms do not return a value directly.

5. •Proceduresare just like small programs.
• Sometimes they are called sub--programs.They help the programmer to avoid
repetitions.
• A procedure start off with a begin and ends up with an end;.
• It can also have its own variables, which cannot be used with the main-program.
Procedure Procedure name( Var Variable Name : Type );

6. Program Lesson1_Program1 (input,output);
Var
Procedure Square(X : Integer; Var y : Integer);
var
Begin
…………
End;
Begin
………….
End.

7. New knowledge aboutVariables !

8. There is aTwo type of Variables :
Global Variables :
That which we define in ProgramVar
Local Variable :
ThatWhich we define inside of our procedure/function or
in procedure/function signature

9. What is the signature !!!

10. What is the signature !!!
Procedure Procedure name( Var Variable Name : Type );Var Variable Name : Type

11. What is the prototype {define} !!!

12. What is the prototype !!!
Procedure Procedure name( Var Variable Name : Type );

13. Program Lesson1_Program1 (input,output);
Var
Z :integer ;
Procedure Square(X : Integer; Var y : Integer);
var
moxo :real ;
Begin
…………
End;
Begin
………….
End.

14. Program Lesson1_Program1 (input,output);
Var
Z :integer ;
Procedure Square(X : Integer ; Var y : Integer);
var
moxo :real ;
Begin
…………
End;
Begin
………….
End.
When you declare parameters to a
procedure, variables must separated
by a semi-colon ";".They are put in
between the brackets, following the
procedure name.

15. Program Lesson1_Program1 (input,output);
Var
X , Z : integer ;
Procedure Square(R : Integer ; Var Result : Integer);
Begin
Result := R * R ;
End;
Begin
Readln(X);
Square(X,Z);
Writeln('The square of X is: '); Writeln( Z );
End.

16. Program Lesson1_Program1 (input,output);
Var
X , Z : integer ;
Procedure Square(R : Integer);
Var
Result : Integer;
Begin
Result := R * R ;
writeln ('The square of X is: ' , Result);
End;
Begin
Readln(X);
Square(X);
End.

17. •Let’sTalk a little bit a bout our built in function !!

18. • ABS( -5 ) 5
• Chr( 97 ) a
• Ord( ‘ a ’ ) 97
• Sin(x) Cos(x)
• Pred( 6 ) 5
• Sqr( 3 ) 9
• Sqrt( 9 ) 3
• Odd( 3 ) True
• Even( 3 ) False
• Succ ( 5 ) 6

19. • Round( 3.14 ) 3
• Round( 3.64 ) 4

20. •FunctionareThe second type of sub-program .
• The only difference from the procedure is that the Function return a value at the
end.
• A Function start off with a begin and ends up with an end;.
• It can also have its own variables, which cannot be used with the main-program.
Function FunctionName(Var VariableName:Type): Return Type;

21. Program Lesson1_Program1 (input,output);
Var
Function Square(X : Integer): Integer ;
var
Begin
…………
End;
Begin
………….
End.

22. Program Lesson1_Program1 (input,output);
Var
X , Z : integer ;
Function Square(R : Integer) : Integer;
Begin
Square := R * R ;
End;
Begin
Readln(X);
Z:= Square(X);
Writeln('The square of X is: '); Writeln( Z );
End.