Delphi Tutorial # 6

Console Application 

Before we go further with visual programming, it is important to understand the basic element of Delphi. In the first tutorial about, I have mention that a console application is a DOS (Disk Operating System) application. It is a non Windows application. Using console programming, you can focus on the codes only. Meanwhile you can forget about visual programming, and learn about Pascal language.

To make a console application, choose File – Close All (if thee is still a form in IDE). Then choose File – New, select Console Application. Delphi will show Project1.dpr window :

Declare constants and variables after uses SysUtils;

  const

   length : integer = 12;

   width : integer = 8;

  var

   area : integer;

Insert user code between begin …. end.

  area := length*width;

  writeln('Length of rectangle = ',length);

  writeln('Width of rectangle = ',width);

  writeln('The area = ',area);

  readln;

The complete codes of Project1.dpr :

  program Project1;

  {$APPTYPE CONSOLE}

  uses

   SysUtils;

  const

   length : integer = 12;

   width : integer = 8;

  var

   area : integer;

  begin

   // Insert user code here

   area := length*width;

   writeln('Length of rectangle = ',length);

   writeln('Width of rectangle = ',width);

   writeln('The area = ',area);

   readln;

  end.

Run the program, and the result is :

The last code readln; is for delaying program until you press Enter button.

Comment

// Insert user code here is an example of comment. Comment can be written in three ways :

-         Written between { }

-         Written between * *

-         Begun with // like the example above

Assigning a value to a variable

From the program above, we assign a value to area variable using assignment operator :=. The syntax is :

    variable := value;

so the code is :

    area := length*width;

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