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IsPathDelimiter

Function IsPathDelimiter( const S : string; Index : Integer) : Boolean

Example​

procedure ScriptEvent(var Value: variant);
begin
  Value := IsPathDelimiter('C:\Fictional', 3);
  // True: the third character is a backslash
end;

Usage​

IsPathDelimiter tests whether a one-based string position contains the platform path delimiter.

Parameters

NameTypeDescription
Sstring, constString whose indexed character is to be tested.
IndexIntegerOne-based string position. Zero, negative and positions beyond Length(S) are accepted and return False.

Returns

True only when Index is in range, the character equals the platform delimiter and the RTL classifies that position as a single-byte/MBCS-safe character; otherwise False.

Behaviour

  • Indexing is Pascal-style and one-based: the first character is position 1.
  • On Windows, a backslash at an in-range position returns True.
  • An empty string or any out-of-range index returns False.
  • A forward slash returns False in Velox on Windows.

Errors

Out-of-range indices do not raise; they return False. Argument conversion and unexpected runtime failures can still occur before entry.

Usage notes

Use the function when reproducing Velox path-delimiter semantics. For a general “slash or backslash” check, test the intended characters explicitly.

Additional Technical Info​

IsPathDelimiter tests whether the character at the one-based Index in S is the platform PathDelim. On the current Windows Velox build, that delimiter is backslash.

The example is source-reviewed and was not executed by the documentation workflow.

Implementation

The wrapper calls installed System.SysUtils.IsPathDelimiter. The current RTL checks Index >= Low(string), Index <= High(S), S[Index] = PathDelim, and ByteType(S, Index) = mbSingleByte. The bounds tests occur before indexing, so invalid positions return False rather than raising through this function.

Edge cases and quirks

  • Some Embarcadero descriptions mention '/' or '\\' generically, but the installed routine compares the single platform PathDelim; for this Windows product that is backslash.
  • The ByteType condition is retained from MBCS-aware RTL code. Script strings are Unicode, but Velox still executes this exact installed terminal implementation.
  • The function recognises one character only. It does not validate a full path, UNC prefix, drive designator or separator placement.
  • Mixed-separator or URL text should use an explicitly appropriate parser rather than this platform test.

Side effects

None.

Performance and concurrency

Constant-time with no allocation or mutable shared state.

Related entries

External references

Created 2026-07-15