error when translating from visual basic to delphi

[binbyte]

Hi everybody!
I have a problem when translating a piece of code from a visual basic program to another in delphi:
I have in vb the following:
i = 1
do while (i < n)
if Vect1(i) = Vect1(i + 1) then
For j = 1 to n
a(i + 1 , j) = a(i + 1 , j) + a(i , j)
a(i , j) = 0
next
end if
i= i + 1
loop

and in delphi

i := 1;
while (i < n) = true do
if Vect1^ = Vect1^[i + 1] then
Begin
For j := 1 to n do
Begin
a^[i + 1 , j] := a^[i + 1 , j] + a^[i , j];
a^[i , j] := 0;
end;
end;
Inc(i);
end;

Vect is a pointer to string and a is a pointer to integer, if it's true then it execute the code.
There's no problem in visual basic but in delphi it's wrong. I don't know why.

Please excuse me for my bad english and thanks if anyone help me

 

[svanels]

How did you define vect1 and a ?

The correct sintax is

vect1 and a[i,j]

Steven

 

[binbyte]

Vect1 and a definition are the following:

UNIT Util;

INTERFACE

TYPE
Float = Double;

CONST
TNArraySize = 500; { Maximum size of matrix }

TYPE
PTNV = ^TNvector;
PTNM = ^TNmatrix;
PTSV = ^TSVector;
PTSM = ^TNSmatrix;
TSvector = ARRAY[1..TNArraySize] OF string;
TNvector = ARRAY[1..TNArraySize] OF integer;
TNmatrix = ARRAY[1..TNArraySize] OF TNvector;

VAR

a : PTNM;
SVect1 : PTSV;

 

[svanels]

The pointer annotation is an old technology used in Turbo Pascal. It forced the programmer to do dynamic allocation of memory and other stuff related to hardware. In times when hardware was expensive ,memory scarce and computing time costly (I started with a 8088, 640K ram, 2 floppies of 360K and no hard disk) the programmer had to know something about electronics (was supposed to have an electrical engineering degree) when programs were getting a little big.
This type of programming has been substituted by object oriented programming, (at start-up the program doesn't need to tell to the compiler what he needs to do the job).

In traditional TP, you had to declare what resources where needed, thus the ^pointer annotation was a workaround.

My suggestion:
TYPE
TSvector = ARRAY[1..TNArraySize] OF string;
TNvector = ARRAY[1..TNArraySize] OF integer;
TNmatrix = ARRAY[1..TNArraySize] OF TNvector;

VAR
a : TSVECTOR; etc..

Else you must make use of commands like GetMem, FreeMem, New, Dispose and others which are already replaced in Delphi. I think that the only survivor of this dos era is Nil

Steven

 

[whosrdaddy]

small language enhancement

i := 1;
  [b]while (i < n) do[/b]
    if Vect1[i] = Vect1[i + 1] then
      Begin
      For j := 1 to n do
        Begin
        [b]Inc(a[i + 1 , j], a[i , j]);[/b]
        a[i , j] := 0;
        end;
      end;
    Inc(i);
  end;

cheers

--------------------------------------
What You See Is What You Get

 

[binbyte]

to whosrdaddy:
I think it's a infinite loop. can i use the following?

i := 1;
repeat
if Vect1 = Vect1[i + 1] then
Begin
For j := 1 to n do
Begin
Inc(a[i + 1 , j], a[i , j]);
a[i , j] := 0;
end;
end;
Inc(i);
Until (i>= n);

to svanels:
what i have to use instead of New() Dispose();?
I learnt something from pascal using turbo Pascal 5.

 

[whosrdaddy]

why an infinite loop??

it all depends on the initial value of n offcourse.
please do remind that in pascal, you need to initialize your variables first (vb did thid for you)

so if I have this

procedure someproc;

var b: boolean;

begin
 if b then
  begin
   showmessage('uncertain');
  end;
end;

you'll see that b wasn't initialized, so you don't know what value it has (sometimes, it will be false, sometime it will be true, this depends what the memory location of the boolean

--------------------------------------
What You See Is What You Get

 

[svanels]

You don't need to use New and Dispose (they are required when using pointers ^. The errors you received had probably something to do with allocation of memory. Using variables before they are declared.

Steven