eyebol Warnings

For Loop count being reduced

If a ‘For’ loop uses the number of items on a list (such as a TList, TStringList, etc.) then a check is made to see if items from that list are removed.

  For I:=0 To StrList.Count-1 do //where strlist is a TStringList
    if State then
      StrList.Delete(I); //this will cause an access violation

An attempt is made to access an item on the list that no longer exists. There are a number of possible solutions. Two of these might be to use a while statement or to use downto in the for loop and count in descending order in the loop. Possible solution 1:

  For I:=StrList.Count-1 downto 0 do //where strlist is a TStringList
    if State then
      StrList.Delete(I);

Possible solution 2:

  I:=0;
  while I<StrList.Count do begin//where strlist is a TStringList
    if State then
      StrList.Delete(I);
    Inc(I);
  end;

< Back to list of hints and warnings