View original (French)

Functions and procedures in DELPHI 7

need ur help -  
 montecristo -
Hello everyone,
I am currently learning Delphi using an online guide which can be found here: https://fbeaulieu.developpez.com/guide/

However, I encountered a problem with the functions:
I followed step by step what was described in the guide (creating a project, declaring the function, etc.) but the compiler found many errors, notably it didn't recognize the variable "result" even though it is supposedly predefined!! (That's what I understood) with functions! Is it because of the version of Delphi?

Looking forward to your responses!!
Configuration: Windows XP Firefox 1.5.0.12

3 réponses

Réponse 1 / 3
montecristo
 
The problem comes from the fact that you do not implement your function in your unit calculation
your function
unit calculation;

interface
{this part is good}
function AireDisque(Rayon: Single): Single;

implementation
{here you need to implement your method like this}
//start of method
function AireDisque(Rayon: Single): Single;

begin
Result := PI * Rayon * Rayon;
end; //end of method

end.
once you are sure of your code, save the unit calculation
and add it to the uses clause
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, calcul;

normally you should see it appear
I write my own procedures or functions in a separate unit first on a form to test, then I copy them into my file
one trick, look at how Delphi constructs these procedures with components, it will save you time
for example your button, look at the events assigned to it
how they declare them and where the methods are located
2
Réponse 2 / 3
amira
 
Hello,
I am working on an arithmetic operation but I have a problem with the result which is for example 6.66666........ I know there is a predefined function in Delphi, please I need this function
thank you.
1
Réponse 3 / 3
need ur help
 
Hello, it's me again!
Here is exactly what I did in my Delphi
I created a project (premierEssai.dpr) containing a unit 'principale.pas' with its form (forme1); and a calculation unit (without a form)

Here is the body of principale:
unit principale;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls,calcul;

type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
aire : single;
begin
ShowMessage ('Bravo! Good answer :)');
aire := AireDisque(3.2);
end;

end.

And the body of the calculation unit

unit calcul;

interface
function AireDisque(Rayon: Single): Single;

implementation
function AireDisque(Rayon: Single): Single;

begin
Result := PI * Rayon * Rayon;
end;

end.

And after compilation here are the errors that the compiler displays:
[Error] calcul.pas(7): Declaration expected but identifier 'AireDisque' found
[Error] calcul.pas(10): Undeclared identifier: 'Result'
[Error] calcul.pas(10): Undeclared identifier: 'Rayon'
[Error] calcul.pas(11): '.' expected but ';' found
[Error] calcul.pas(4): Unsatisfied forward or external declaration: 'AireDisque'
[Fatal Error] principale.pas(8): Could not compile used unit 'calcul.pas'

Please help me understand better
and thank you in advance.
0