Need help on array plz

[ilusion]

how calculate the number of  empty box in array     ???

[howardpc]

Here's a small example to show one way to do this.
In a new Lazarus project double-click the main form to generate an OnClick handler,and complete the unit as follows:

Code: [Select]

unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  SysUtils, Forms, StdCtrls, strutils, Controls;

type

{ TForm1 }

  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure TForm1.FormCreate(Sender: TObject);
var
  r: integer = 0;
  s: string;
  arr: array of string;
  memo: TMemo;

  function CountEmpty: integer;
  var
    p: integer;
  begin
    Result:=0;
    for p:=Low(arr) to High(arr) do
      if (arr[p] = '') then
        Inc(Result);
  end;

begin
  Randomize;
  memo:=tmemo.Create(Self);
  memo.Clear;
  memo.Align:=alClient;
  memo.ScrollBars:=ssAutoVertical;
  memo.Parent:=Self;

  while (r = 0) do
    r:=Random(100);
  SetLength(arr, r);
  for r:=Low(arr) to High(arr) do begin
    s:=IntToRoman(r);
    if (Pos('X',s) > 0) then
      arr[r]:=s
    else arr[r]:='';
    if (arr[r] = '') then
      memo.Lines.Add('[empty]')
    else memo.lines.Add(arr[r]);
  end;
  memo.Lines.Insert(0, Format('%d empty positions in array (%d total positions)',
                              [CountEmpty, Length(arr)]));
end;

end.


[User137]

Code: [Select]

type
  TBox = record
    empty: boolean;
  end;

var
  boxes: array[0..9] of TBox;
  n, empties: integer;
begin
  empties:=0;
  for n:=low(boxes) to high(boxes) do
    if boxes[n].empty then inc(empties);
  writeln(empties);
end;

[ilusion]

thank you but
He always display 0  !!!

Example
I have a table consists of 5 boxes i filling 2 boxes
I want to show me number of the boxes, which is still empty
( n = 3 )

[BitBangerUSA]

you should show your code.

who is 'He'?

did you follow howardpc or User137? both? neither?

[ilusion]

i follow howardpc

[BitBangerUSA]

i tried what howardpc posted...

after a couple of changes to his instructions, i got:

9 empty positions in array (41 total positions)
[empty]
[empty]
[empty]
[empty]
[empty]
[empty]
[empty]
[empty]
[empty]
IX
X
XI
XII
XIII
XIV
XV
XVI
XVII
XVIII
XIX
XX
XXI
XXII
XXIII
XXIV
XXV
XXVI
XXVII
XXVIII
XXIX
XXX
XXXI
XXXII
XXXIII
XXXIV
XXXV
XXXVI
XXXVII
XXXVIII
XXXIX
XL


did you get anything?
can you post your code?

[ilusion]

I want the number of empty boxes only
Example

I have 5 boxes i filling 2 boxes
Write me  n = 3  (n = numbre of empty boxes )

program Untitled;
type
  prsonne = record
  name : string;
  empty: boolean;
  end;

var
  boxes: array[0..9] of prsonne ;
  n, empties: integer;
begin
      for n := 0 to 3 do
      begin
      writeln (' enter the first name : ' );
      readln(boxes[n].name);
      end;
  empties:=0;
  for n:=low(boxes) to high(boxes) do
    if boxes[n].empty then inc(empties);
  writeln(empties);
  readln;

end.

[BitBangerUSA]

you are not setting the boolean empty in the loop where you get the names, but are then checking empty in the second loop. of course, the results will be wrong.

i don't see a good reason to have the boolean part of the record - simply check for Name <> '' if you want to know how many empty records there are.

[Eugene Loza]

Code: [Select]

boxes: array[0..9] of prsonne ;So you have 10 boxes total (not 5).

Code: [Select]

for n := 0 to 3 doThen you make the user input 4 first items (not 2)
He can also input an empty string, right?
so if the box is empty it should contain '' string:

Code: [Select]

empties:=0;
  for n:=low(boxes) to high(boxes) do
    if boxes[n].name='' then inc(empties);
  writeln(empties);So, in this way you don't need empty: boolean; or you should "define" it at the input process (pay attention, the variable is not initialized, and default is 'false', this is why you get 0 empties).

[ilusion]

What  i do now  help me 
i want  know how many empty boxes there are

or

how many boxes records there are

[BitBangerUSA]

Code: [Select]

program Untitled;
{type
  prsonne = record
  name : string;
  empty: boolean;
  end;}

var
  boxes: array[0..9] of string;
  n, empties: integer;
begin
      for n := 0 to 3 do
      begin
      writeln (' enter name : ' );
      readln(boxes[n]);
      end;
  empties:=0;
  for n:=low(boxes) to high(boxes) do
    if boxes[n] = '' then inc(empties);
  writeln(empties);
  readln;

end.
         

you should re-consider why you are setting the input name loop to run 4 times... why 4? unless you did that only for test purpose.

[mangakissa]

Code: [Select]

program Untitled;

type
  prsonne = record
  name : string;
  empty: boolean; //is useless
  end;

var
  boxes: array[0..9] of prsonne ;
  n, empties: integer;
begin
      //first read your array and set their properties to default
      for n := low(boxes) to high(boxes) do
        boxes[n].name := '';

      // the rest of your code
      for n := 0 to 3 do
      begin
      writeln (' enter the first name : ' );
      readln(boxes[n].name);
      end;
  empties:=0;
  for n:=low(boxes) to high(boxes) do
    if trim(boxes[n].name) = '' then inc(empties);
  writeln(empties);
  readln;

end.
functions low() and high() are also useless here, because you create a static array of 10 elements.

[Bart]

functions low() and high() are also useless here, because you create a static array of 10 elements.

No they are not. Whenever he decides to change the static dimensions of the array, this code will still work.

Bart