IOSTREAM question : should ends manipulator flush buffer?

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3 total messages Started by Stuart Maclean Tue, 16 Apr 1996 12:27

#4057

Author: Stuart Maclean
Date: Tue, 16 Apr 1996 12:27

31 lines
1666 bytes

Hi, I'm currently implementing a stream class where the external
representation is a socket.  Whilst playing with the following

TCPSocket tcp;
....
Sockstream  ss( tcp );

ss << "Hello World!" << endl;
ss << "Hello World!" << ends;

I noticed that manipulator "endl" synchronises with the external
representation, but "ends" does not.  Tracing our IOStream library,
libg++-2.7.1, it indeed does not do a flush when using "ends".  In C++PL2
by Stroustrup, page 348 has a comment implying that "ends" should do a
flush.

Does anyone know the correct behaviour for "ends" in the Standard C++
Library, whatever that is and whenever it may appear 8-)

Any help gratefully appreciated.

Stuart

-- 
Stuart
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Re: IOSTREAM question : should ends manipulato

#4066

Author: Steve Clamage
Date: Tue, 16 Apr 1996 20:17

19 lines
1634 bytes

In article 1604961139410001@galois.ecs.soton.ac.uk, S.D.Maclean@ecs.soton.ac.uk (Stuart Maclean) writes:
>
>I noticed that manipulator "endl" synchronises with the external
>representation, but "ends" does not.  Tracing our IOStream library,
>libg++-2.7.1, it indeed does not do a flush when using "ends". 

That is correct. It has always been the case (and is still the case
in the draft standard) that "ends" inserts a null character but does
not flush, and "endl" inserts a newline character followed by a flush.

---
Steve Clamage, stephen.clamage@eng.sun.com
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Re: IOSTREAM question : should ends manipulator flush buffer?

#4078

Author: James Kanze US/ESC 60/3/141 #407...
Date: Wed, 17 Apr 1996 14:57

41 lines
2526 bytes

In article <sdm-1604961139410001@galois.ecs.soton.ac.uk>
S.D.Maclean@ecs.soton.ac.uk (Stuart Maclean) writes:

|> Hi, I'm currently implementing a stream class where the external
|> representation is a socket.  Whilst playing with the following

|> TCPSocket tcp;
|> ....
|> Sockstream  ss( tcp );

|> ss << "Hello World!" << endl;
|> ss << "Hello World!" << ends;

|> I noticed that manipulator "endl" synchronises with the external
|> representation, but "ends" does not.  Tracing our IOStream library,
|> libg++-2.7.1, it indeed does not do a flush when using "ends".  In C++PL2
|> by Stroustrup, page 348 has a comment implying that "ends" should do a
|> flush.

|> Does anyone know the correct behaviour for "ends" in the Standard C++
|> Library, whatever that is and whenever it may appear 8-)

The draft standard says nothing about a possible flush.

Given that ends means end of *string*, and the flush function is a
no-op in ostringstream, it's possible that the standards committee
simply felt that it wasn't necessary.  (It's also possible that this is
an oversight in the draft.)
-- 
James Kanze         Tel.: (+33) 88 14 49 00        email: kanze@gabi-soft.fr
GABI Software, Sarl., 8 rue des Francs-Bourgeois, F-67000 Strasbourg, France
Conseils, études et réalisations en logiciel orienté objet --
                -- A la recherche d'une activité dans une region francophone



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