Best way to empty stringstream?

Question

One of the possibilities is:

somestringstream.str("");

But is it most optimal? Is there any way to preserve stringstream internal buffer, so that following operator<<() calls would not require to reserve memory again?

It was discussed here: http://stackoverflow.com/questions/624260/how-to-reuse-an-ostringstream — Johannes Schaub - litb, May 07 '09 at 13:26

score 51 · Accepted Answer · edited May 23 '17 at 11:54

51

I've always done:

s.clear();//clear any bits set
s.str(std::string());

@litb gets into more detail about how to seekp to the start of the stream combined with std::ends you can keep your allocated size.

edited May 23 '17 at 11:54

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answered May 07 '09 at 13:25

Brian R. Bondy

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or simply ss.str(""); //more intuitive – Milan May 07 '09 at 13:33
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@milan1612: You would still need to clear the bits, and sending a C-style char* will be slower. – Drew Dormann May 18 '09 at 00:14
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..and [this explains](http://stackoverflow.com/questions/20731/in-c-how-do-you-clear-a-stringstream-variable) why the `s.str(std::string())` variant _could_ be more efficient. – Andreas Spindler Jan 26 '12 at 11:48

Best way to empty stringstream?

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