Delphi – Is WideString identical to String in Delphi 2009


I'm getting some weird behaviour recompiling some applications in 2009 that used widestrings at various points.

In a Delphi 2009 App is Widestring identical to String?

Best Solution

No, they are not idenitical.

WideString is just a wrapper for the ActiveX/COM BSTR type. You need it when working with with strings in ActiveX/COM.

String in Delphi 2009 and later is an alias for UnicodeString, which can hold Unicode characters, just like BSTR does, but it's NOT the same as WideString. WideString is allocated by the COM memory manager, and is not reference counted. UnicodeString is allocated by the RTL memory manager, and is reference counted, just like AnsiString is.

You should use (Unicode)String wherever possible, and only use WideString for COM interop, or dealing with legacy libraries that use WideString for Unicode support.