How can I use a ifstream object to input from stdin?
Ex.
ifstream inf;
if (fn=="-")
{ what here to use inf as cin?
}
else
{ inf.open(fn.c_s tr,ios::in);
}
inf >...
Thanks.
4  8720 
Paulo da Silva wrote:
How can I use a ifstream object to input from stdin?
On some systems, opening "/dev/stdin" might work, but the general solution
is to use a pointer:
>
Ex.
ifstream inf;
istream *inf;
if (fn=="-")
{ what here to use inf as cin?
inf = &cin;
}
else
{ inf.open(fn.c_s tr,ios::in);
inf = new ifstream(fn.c_s tr());
}
inf >...
*inf >...
....
if (inf == &cin)
delete inf;
--
rbh
Robert Bauck Hamar wrote:
Paulo da Silva wrote:
>How can I use a ifstream object to input from stdin?
On some systems, opening "/dev/stdin" might work, but the general solution
is to use a pointer:
>>
Ex.
ifstream inf;
istream *inf;
>if (fn=="-")
{ what here to use inf as cin?
inf = &cin;
>}
else
{ inf.open(fn.c_s tr,ios::in);
inf = new ifstream(fn.c_s tr());
>}
inf >...
*inf >...
...
if (inf == &cin)
Just a nit. I think, you want:
if ( inf != &cin )
delete inf;
Best
Kai-Uwe Bux
Robert Bauck Hamar escreveu:
Paulo da Silva wrote:
>How can I use a ifstream object to input from stdin?
On some systems, opening "/dev/stdin" might work, but the general solution
is to use a pointer:
>Ex.
ifstream inf;
istream *inf;
>if (fn=="-")
{ what here to use inf as cin?
inf = &cin;
>}
else
{ inf.open(fn.c_s tr,ios::in);
inf = new ifstream(fn.c_s tr());
>}
inf >...
*inf >...
...
if (inf == &cin)
!=
delete inf;
Thank you. This works ...
On Jul 12, 6:24 pm, Robert Bauck Hamar <roberth+n...@i fi.uio.no>
wrote:
Paulo da Silva wrote:
How can I use a ifstream object to input from stdin?
On some systems, opening "/dev/stdin" might work, but the general solution
is to use a pointer:
Or a reference.
Ex.
ifstream inf;
istream *inf;
if (fn=="-")
{ what here to use inf as cin?
inf = &cin;
}
else
{ inf.open(fn.c_s tr,ios::in);
inf = new ifstream(fn.c_s tr());
}
inf >...
*inf >...
...
if (inf == &cin)
delete inf;
More frequent, I think, is something along the lines of:
if ( argc == 1 ) {
process( std::cin ) ;
} else {
for ( int i = 1 ; i < argc ; ++ i ) {
std::ifstream in( argv[ i ] ) ;
if ( ! in ) {
std::cerr << "Could not open: " << argv[ i ] <<
std::endl ;
} else {
process( in ) ;
}
}
}
All the work is then done in "process( std::istream& )".
--
James Kanze (Gabi Software) email: ja*********@gma il.com
Conseils en informatique orientée objet/
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