This page is a snapshot from the LWG issues list, see the Library Active Issues List for more information and the meaning of CD1 status.

566. array forms of unformatted input function undefined for zero-element arrays

Section: [istream.unformatted] Status: CD1 Submitter: Martin Sebor Opened: 2006-02-23 Last modified: 2017-02-03

Priority: Not Prioritized

View all other issues in [istream.unformatted].

View all issues with CD1 status.


The array forms of unformatted input functions don't have well-defined semantics for zero-element arrays in a couple of cases. The affected ones (istream::get() and getline()) are supposed to terminate when (n - 1) characters are stored, which obviously can never be true when (n == 0) to start with.

Proposed resolution:

I propose the following changes (references are relative to the Working Draft (document N1804).

Change, p8 (istream::get()), bullet 1 as follows:

if (n < 1) is true or (n - 1) characters are stored;

Similarly, change, p18 (istream::getline()), bullet 3 as follows:

(n < 1) is true or (n - 1) characters are stored (in which case the function calls setstate(failbit)).

Finally, change p21 as follows:

In any case, provided (n > 0) is true, it then stores a null character (using charT()) into the next successive location of the array.