strange behavior of stringstream

[linyanhung]

In case A(see below), ss.clear() doesn't work and have no error
message. cout<<ss.str() shows "xcv".

In case B ss.clear() works normally and cout<<ss.str() shows
nothing.

Can anyone tell me why ? Thanks.

Case A:

stringstream ss;
ss<<"xcv";
{
ss.clear();
cout<<ss.str();
}

---------------------------
Case B:

{
stringstream ss;
ss<<"xcv";
ss.clear();
cout<<ss.str();

}

[Alf P. Steinbach]

* li********@gmail.com:

In case A(see below), ss.clear() doesn't work and have no error
message. cout<<ss.str() shows "xcv".

In case B ss.clear() works normally and cout<<ss.str() shows
nothing.

Can anyone tell me why ? Thanks.

Case A:

stringstream ss;
ss<<"xcv";
{
ss.clear();
cout<<ss.str();
}

---------------------------
Case B:

{
stringstream ss;
ss<<"xcv";
ss.clear();
cout<<ss.str();

}

There should be no behavioral difference.

'clear' doesn't clear the contents of the stream.

It's inherited from std::ios, and clears the state flags.

--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

[linyanhung]

Thanks Steinbach .

But under the VS2005 they do have behavioral difference.

Now I use ss.str(""); instead of ss.clear() to solve the problem.
Alf P. Steinbach ¼g¹D¡G

>
There should be no behavioral difference.

'clear' doesn't clear the contents of the stream.

It's inherited from std::ios, and clears the state flags.

--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?