🚀 go-pugleaf

joost witteveen (joost@rulcmc.leidenuniv.nl) wrote:
>  If I construct a ostrstream, with
>    ostrstream os (s,sizeof(s))
>  do I have to clean ALL of s before I use it?
>  I'm getting strange results (i.e. I have to init ALL of s to 0)
>  with g++ 2.7.1, and 2.3.3.

>  So, my question is: is this a bug in g++, or am I missing something
>  about the string streams?


>  The following programme has this what I think is strange behaviour,
>  as it outputs in the last line not only the "hello, world", but
>  part of the old h's string s was inititalized to,  concatenated to it.

>  Thanks for any suggestions.


>  #include <iostream.h>
>  #include <strstream.h>
>  int main(int,char **){
>    int i;
>    char s[]="\000hhhhhhhhhhhhhhhhhhhhhhhhhhhh";
>    cout<<"initial s:"<<s<<endl; //an empty string here.

>    ostrstream os(s,sizeof(s));
>    os<<"hello, world";
>    cout<<s<<endl;          //outputs: hello, worldhhhhhhhhhhhhhhhhh
>  }

You forgot to append a '\0', which is _not_ done automatically by
'ostrstream'. There is a special manipulator 'ends' which does exactly
this:

   os << "hello world" << ends;

Now the string is correctly '\0'-terminated.

	Bernd

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