CODEWITHSUNDEEP
arraysstringinno-setuppascal
MarkOccam
MarkOccam

Reputation: 97

Inno Setup Acces violation increment array of strings

I hava an array of strings. I increment this array when it is necessary with the function:

function insertMessageAction(list: TMessagesActions; message: String): TMessagesActions;
var
  lenght: integer;
begin
  if message <> '' then begin
    lenght := GetArrayLength(list);
    SetArrayLength(list, lenght +1);
    if GetArrayLength(list) > lenght then begin
      list[lenght] := message
    end;
  end;
  result := list;
end;

If de increment is of 0 to 2, no problems, by when I increment to 3 lenght, the array is corrupted and 'value' of list is: "Acces violation at address 00403498. Read of address 0000006A".

It is impossible to create more long arrays of 2 items (strings)? There is limit of characters?

Thanks.

Upvotes: 1

Views: 734

Answers (1)

TLama
TLama

Reputation: 76713

First of all, do not use array for your task. Memory reallocation that happens when changing the size of your string array is an expensive operation. What's more, you were trying to return a copy of that input array (in a wrong way), which would be unecessarily inefficient too.

I strongly suggest you to use the TStringList which is intended to be used for a collection of strings. By using TStringList, the whole code from your question would become:

StringList.Add(Message);

But to your question. It is possible, but you need to comply with a few things; at least:

  1. Do not attempt to return an input array passed by reference:

    Result := list;

  2. If you need to have an array as a return type for some reason, allocate the size of this output array and copy all the elements from the input array:

    InputLen := GetArrayLength(List);
SetArrayLength(Result, InputLen + 1);
for I := 0 to InputLen - 1 do
  Result[I] := List[I];

Result[InputLen] := Message;

  3. If you'd still like to stay by array, better pass it by variable parameter:

    [Code]
type
  TMessagesActions = TArrayOfString;

procedure InsertMessageAction(var AList: TMessagesActions;
  const AMessage: String);
var
  ArrayLen: Integer;
begin
  ArrayLen := GetArrayLength(AList);
  SetArrayLength(AList, ArrayLen + 1);
  AList[ArrayLen] := AMessage;
end;

Upvotes: 3

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