SysUtils.ExtractFileExt

[Aqdam1978@yahoo.com]

Hello,

There is a bug in the ExtractFileExt function, when a file's name is null, this function returns null, for example:

SysUtils.ExtractFileExt('sample.txt') returns ".txt" however, SysUtils.ExtractFileExt('.txt') returns ""

Is there any other routine to extract filename's extension?

Thanks,

[trev]

SysUtils.ExtractFileExt('sample.txt') returns ".txt" however, SysUtils.ExtractFileExt('.txt') returns ""

Which is correct because the filename ".txt" has no file extension. In UNIX and UNIX-like circles it is a hidden file.

[Aqdam1978@yahoo.com]

It's not correct! file name format should be like "name.ext"

if you try SysUtils.ExtractFileName('.txt') it will return null too!
so both functions return null.

SysUtils.ExtractFileExt('.txt') retuns ""
SysUtils.ExtractFileName('.txt') retuns ""

I expect to get ".txt" when I am calling the SysUtils.ExtractFileExt('.txt')

[devEric69]

if you try SysUtils.ExtractFileName('.txt') it will return null too!

I agree: in Linux, if '.txt' is the full name (so, without\no extension in this case) of a hidden file, SysUtils.ExtractFileName('.txt') should return the whole '.txt', imo (not null). No?

[Kays]

if you try SysUtils.ExtractFileName('.txt') it will return null too!

No, it doesn’t, unless you’ve altered allowDirectorySeparators/allowDriveSeparators.

As trev already wrote, extractFileExt('.txt') correctly returns an empty string. The term file extension implies you’re extending a name. What “name” would you like to extend in .txt? Exactly, there is no name. On no OS in the world an empty string would constitute a valid file name, thus the entire string '.txt' is the file name and there is no file name extension.

[Bart]

This behaviour is controlled by the global var FirstDotAtFileNameStartIsExtension.
It's default value is FALSE.

Code: Pascal  [Select][+][-]

1.   FirstDotAtFileNameStartIsExtension := False;
2.   S := extractfileext('.txt');
3.   writeln('"',S,'"');
4.   FirstDotAtFileNameStartIsExtension := True;
5.   S := extractfileext('.txt');
6.   writeln('"',S,'"');

Outputs:

Code: [Select]

""
".txt"

Bart