Hi,
    Can anyone help me with this one?  Under an earlier compile (CW
Pro2) I was able to create one C++ object of type 'ostringstream' and
reuse it in the same scope continually by:

    myOStringStream.seekp(0);

Doing so also zeroed out the string (probably not the correct thing to
do according to the standard, but it was useful to me.)

However, CW Pro5, places the insert point at the beginning of the string
but does NOT zero out the string (most likely the standard behaviour.)

I want to use the same object over and over in the particular scope
because there are so many things I have to do (i.e. multiple objects
would avoid the problem, but the construction would kill
performance...there are a lot of strings and it's in an intensive
real-time program.)

How do I do this?

Thanks,
Tim
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Tim Rogstad schrieb:
> However, CW Pro5, places the insert point at the beginning of the strin=
g
> but does NOT zero out the string (most likely the standard behaviour.)

yes, i think so.  at least, it should be.  however, you can do this:

myOStringStream.str(string());
myOStringStream.clear();       // clear error flags

> I want to use the same object over and over in the particular scope
> because there are so many things I have to do (i.e. multiple objects
> would avoid the problem, but the construction would kill
> performance...there are a lot of strings and it's in an intensive
> real-time program.)

well, performance could be an issue with my suggestion because there
are strings created.  just give it a try.

regards

 robert

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Looks like the best way is as follows:

   myOStringStream.str(constEmptyString);

assuming you have defined something like:

   static const string constEmptyString;

or you could just us a literal:

   myOStringStream.str("");

These will also reset the position so you don't need to call seekp(0).

Anders.



In article <37B08AC0.7ECA10C2@jpl.nasa.gov>, Tim Rogstad
<timothy.d.rogstad@jpl.nasa.gov> wrote:

>Hi,
>    Can anyone help me with this one?  Under an earlier compile (CW
>Pro2) I was able to create one C++ object of type 'ostringstream' and
>reuse it in the same scope continually by:
>
>    myOStringStream.seekp(0);
>
>Doing so also zeroed out the string (probably not the correct thing to
>do according to the standard, but it was useful to me.)
>
>However, CW Pro5, places the insert point at the beginning of the string
>but does NOT zero out the string (most likely the standard behaviour.)
>
>I want to use the same object over and over in the particular scope
>because there are so many things I have to do (i.e. multiple objects
>would avoid the problem, but the construction would kill
>performance...there are a lot of strings and it's in an intensive
>real-time program.)
>
>How do I do this?
>
>Thanks,
>Tim

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My documentation says that "myOStringStream.flush();" should do the trick.

Tim Rogstad wrote:

> Hi,
>     Can anyone help me with this one?  Under an earlier compile (CW
> Pro2) I was able to create one C++ object of type 'ostringstream' and
> reuse it in the same scope continually by:
>
>     myOStringStream.seekp(0);
>
> Doing so also zeroed out the string (probably not the correct thing to
> do according to the standard, but it was useful to me.)
>
> However, CW Pro5, places the insert point at the beginning of the string
> but does NOT zero out the string (most likely the standard behaviour.)
>
> I want to use the same object over and over in the particular scope
> because there are so many things I have to do (i.e. multiple objects
> would avoid the problem, but the construction would kill
> performance...there are a lot of strings and it's in an intensive
> real-time program.)
>
> How do I do this?



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On 11 Aug 1999 18:33:32 GMT, Robert Klemme <klemme@unity.de> wrote:

>myOStringStream.str(string());
>myOStringStream.clear();       // clear error flags

One should clear the error flags before resetting the str, otherwise it
is possible for the resetting of the str to have no effect.

--
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