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LastDelimiter

function LastDelimiter(const Delimiters, S: string): Integer

Example​

procedure ScriptEvent(var Value: variant);
begin
  Value := LastDelimiter('/\', 'C:\folder/file.txt'); // position of the final slash
end;

Usage​

LastDelimiter returns the one-based position of the rightmost character belonging to a delimiter-character string, or zero when none matches.

Parameters and result

ItemTypeDescription
DelimitersstringIndividual case-sensitive characters that may match. Their order and duplication do not affect which position is returned.
SstringText searched from its final code unit toward its first.
ResultIntegerOne-based matching position, or 0.

For example, LastDelimiter('.:', 'A:B.C') returns the position of '.', because it is the rightmost occurrence of either candidate character. To find the last occurrence of the exact substring '.:', use a substring-search strategy instead.

Additional Technical Info​

LastDelimiter searches S from right to left and returns the one-based position of the first character encountered that appears anywhere in Delimiters. It returns 0 when there is no match.

Delimiters is a set expressed as a string of individual characters; it is not one multi-character substring. The example is fictional and source-reviewed only.

NUL and encoding behavior

The installed Delphi terminal excludes NUL (#0) from matching. It passes Delimiters as a null-terminated PChar to StrScan, so an embedded NUL also terminates the effective delimiter list and characters stored after it are not considered.

The search works on Delphi string code units. Do not use half of a surrogate pair or one byte of a multibyte encoded character as a semantic delimiter. There is no locale or case folding.

This direct RTL function allocates no result string and has no external side effects. Its worst-case work is proportional to the source length multiplied by the effective delimiter-list length.

Related entries

  • BreakStringLast uses this primitive but has a Velox multi-character length defect; supply it one delimiter character only.
  • PosEx searches forward for an exact substring from an offset.

External references

Created 2026-07-15