question

[nanadien]

what happens if you call:
in_file.open("");
without a physical name??

[Disch]

It will try to open a nameless file, which will likely fail because filesystems generally require their files to have names.

[nanadien]

that means it will send an error message?? if does not find nameless file??

[Disch]

it means in_file will not represent an opened file. If you try to do in_file.good() it will return false because no file is opened. Any reads/writes you try to do with in_file will also fail.

Nothing will be output to the user, though. If you want an error message printed you have to do that yourself.

[nanadien]

thanks Disch :)