使用Delphi在另一个字符串中查找变量字符串

Question

Given a field/string like 'G,H,1,AA,T,AAA,1,E,A,H,....'. The characters can be in any combination/order. How do I search that string and return True when searching for just 'A' or 'AA'? ie If doing a search for say 'A', it should only find the 'A' between the E & H. Regards & TIA, Ian

Answer 1

Split this string into a list, for example with TStringList.CommaText (alternatively, into an array with StrUtils.SplitString() ).

Then, just walk through the list and check every string (or use TStrings.IndexOf() - note: it uses CaseSensitive property, as Remy mentioned in comments).

If you are going to make many queries for the same list - sort it and use an effective binary search ( TStringList.Find() ).

Answer 2

You can simply split your string into an array by your delimiter and search in that array, eg

function FindItem(const List, Item: string): Boolean;
var
  SArr: TArray<string>;
  S: string;
begin
  Result := False;
  //Separators could also be a parameter
  SArr := List.Split([',']);
  for S in SArr do
  begin
    //use S.Trim if needed
    //use AnsiSameText(S, Item) for case insensitive check
    if Item = S then
      Exit(True);
  end;
end;

If you need to search for multiple items in your data, you might want to sort the array and use a binary search.

TArray.Sort<string>(SArr);
Result := TArray.BinarySearch(SArr, Item, Tmp);

Another approach would be using regular expressions with word boundaries to search for whole words only

Result := TRegex.IsMatch(List, '\bA\b');