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justaprogrammer@gmail.com
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 Posted: Wed Aug 17, 2005 12:45 pm Post subject: Daisy chaining streams |
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I would like to connect two streams together in the following
bool operator>>(std::istream&i, CDate&d)
{
/*Cartoon of what I want to do....
std::ostringstream ost;
ost<
std::string d = ost.str();
*/
//The following works
char c[100];
i.getline(c,99);
std::string d(c);
....
}
This operator is called by
vector
//See Herb Sutter, Bjarne Stroustrup, etc...
copy ( istream_iterator<CDate> (cin),
istream_iterator<CDate>(),
back_inserter(e));
The user enters dates on the console by typing mm/dd/yy <Enter>. The
"working" code works fine but I do not like th dumb "99" cludge. The
cunning thing is that the getline waits until a '/n' (aka <Enter>) is
struck before continuing - so my cartoon will need a callback too.
I have done this previously by handrolling my own Sink classes - but I
feel streams should be able to do the same.
Any ideas?
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
[ comp.lang.c++.moderated. First time posters: Do this! ]
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Ulrich Eckhardt
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| Posted: Wed Aug 17, 2005 5:18 pm Post subject: Re: Daisy chaining streams |
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[email]justaprogrammer (AT) gmail (DOT) com[/email] wrote:
| Quote: | bool operator>>(std::istream&i, CDate&d)
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Overloaded streaming operators should return the stream by reference, not a
boolean, so you can write:
CDate from, to;
std::cin >> from >> to;
| Quote: | /*Cartoon of what I want to do....
std::ostringstream ost;
ost<
std::string d = ost.str();
*/
//The following works
char c[100];
i.getline(c,99);
std::string d(c);
|
Here, I'd use the free getline() function:
std::string line;
if( std::getline( std::cin, line))
... // use line
else
... // handle IO error
| Quote: | The
cunning thing is that the getline waits until a '/n' (aka
struck before continuing - so my cartoon will need a callback too.
|
Every input requires the user to press enter, how else would you handle
backspaces without? I'm not sure what you mean with the callback.
| Quote: | I have done this previously by handrolling my own Sink classes - but I
feel streams should be able to do the same.
|
I'm really not sure what you want here.
BTW: have you ever wondered what the 'C' in front of classes means? It's a
quirky old way used by the MFC to put their classes into a common namespace
- modern C++ has its own real namespaces.
Uli
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
[ comp.lang.c++.moderated. First time posters: Do this! ]
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