Skip to main content

IndexOf

function IndexOf(const S: string): Integer;

Example​

procedure FindStatus(const Items: TStringList; var FoundAt: Integer);
begin
  FoundAt := Items.IndexOf('Complete');
end;

Usage​

IndexOf returns the first matching string index under the list's comparison policy, or minus one.

  • Test for >= 0; -1 means no match.
  • Do not compare the result with Count as a not-found sentinel.
  • Locale and case settings can make results environment-sensitive.

Additional Technical Info​

IndexOf is declared by hidden ancestor TStrings and is normally used through a concrete visible descendant such as TStringList. Matching can therefore differ from the exact comparison used by Equals.

Source-backed behaviour​

The base implementation scans from index zero and calls virtual CompareStrings until it returns zero. A TStringList override uses a linear scan when unsorted and binary Find when sorted.

For TStringList, CaseSensitive and UseLocale influence comparison. The current script constructor defaults to case-insensitive, locale-aware comparison. A sorted list returns a matching position according to the binary-search path; when accepted duplicates exist, callers must not assume which equal entry is returned.

IndexOfName searches name/value keys and IndexOfObject uses object identity. Equals always performs ordered case-sensitive text equality.

Official RTL references​

Created 2026-07-15