This page is a snapshot from the LWG issues list, see the Library Active Issues List for more information and the meaning of C++11 status.

### 1249. `basic_ios` default ctor

Section: 29.5.4.2 [basic.ios.cons] Status: C++11 Submitter: Martin Sebor Opened: 2009-10-25 Last modified: 2016-01-28

Priority: Not Prioritized

View all other issues in [basic.ios.cons].

View all issues with C++11 status.

Discussion:

The `basic_ios` default ctor is required to leave the objects members uninitialized (see below). The paragraph says the object must be initialized by calling `basic_ios::init()` before it's destroyed but I can't find a requirement that it be initialized before calling any of the class other member functions. Am I not looking in the right place or that an issue?

[ 2009-10-25 Daniel adds: ]

> I agree, that your wording makes that clearer, but suggest to write

> > ... calling `basic_ios::init()` before ...

> Doing so, I recommend to adapt that of `ios_base();` as well, where we have:

> > Effects: Each `ios_base` member has an indeterminate value after construction. These members shall be initialized by calling `basic_ios::init`. If an `ios_base` object is destroyed before these initializations have taken place, the behavior is undefined.

[ Post-Rapperswil: ]

> Moved to Tentatively Ready after 5 positive votes on c++std-lib.

[ Adopted at 2010-11 Batavia ]

Proposed resolution:

Change 29.5.2.8 [ios.base.cons] p1:

>     ios_base();

> > Effects: Each `ios_base` member has an indeterminate value after construction. These The object's members shall be initialized by calling `basic_ios::init` before the object's first use or before it is destroyed, whichever comes first; otherwise the behavior is undefined.. If an `ios_base` object is destroyed before these initializations have taken place, the behavior is undefined.

Change 29.5.4.2 [basic.ios.cons] p2:

>     basic_ios();

> > Effects: Constructs an object of class `basic_ios` (27.5.2.7) leaving its member objects uninitialized. The object shall be initialized by calling its `basic_ios::init` before its first use or before it is destroyed, whichever comes first; otherwise the behavior is undefined. member function. If it is destroyed before it has been initialized the behavior is undefined.