Introduction to the Pascal Programming Language

© 1998 by Dr. Thomas W. MacFarland -- All Rights Reserved


     Instructions:   Review the following program and see if you can 
                     predict the outcome by completing a "pencil 
                     trace" of the code.  

                     Program output is provided at the end of this 
                     page.

     Compiler:       The program was prepared using Standard Pascal 
                     on a UNIX-based host computer.


% cat PASCAL/intro_pencil-09.p
{ Introduction to the Pascal Programming Language
  Dr. Thomas W. MacFarland
  intro_pencil-09.p       
}

{ The purpose of this program is to:

  1.  Demonstrate the selection symbols:  <, >, <=, >=, <>.

  1.  Demonstrate the process used to create a nested loop.    

  2.  Demonstrate conditional statements within a nested loop.     

}
program Demonstrate_If_Statement_in_a_Nested_Loop;

var A, B : integer;

begin

   for A := 1 to 4 do begin 
     if A <= 2 then
       writeln('A = ',A:4);
         if A >= 3 then begin
           for B := 2 to 4 do begin 
             write('A = ',A:4);
             write(' and B = ',B:4);
               if A > 5 then write (' A > 5');
                 if B <> 4 then write (' because B <> 4');
                 writeln;
                 end; 
               end; 
         end;

end.  { intro_pencil-09.p      } 
% pc PASCAL/intro_pencil-09.p
% a.out
A =    1
A =    2
A =    3 and B =    2 because B <> 4
A =    3 and B =    3 because B <> 4
A =    3 and B =    4
A =    4 and B =    2 because B <> 4
A =    4 and B =    3 because B <> 4
A =    4 and B =    4

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