I've posted this in another thread, but I suppose I should've started a
new thread for it instead.
I cannot get the following short program to compile under g++:
#include <iostream>
#include <fstream>
#include <iterator>
#include <algorithm>
using namespace std;
int main(int argc, char **argv)
{
copy(istream_it erator<char>(ar gc >= 2 ? ifstream(argv[1]) : cin),
// this line won't compile!
istream_iterato r<char>(),
ostream_iterato r<char>(cout)) ;
return 0;
}
The compiler error messages are as followed:
/usr/include/c++/4.0.0/iosfwd: In copy constructor
'std::basic_ios <char, std::char_trait s<char::basic_i os(const
std::basic_ios< char, std::char_trait s<char&)':
/usr/include/c++/4.0.0/bits/ios_base.h:779: error:
'std::ios_base: :ios_base(const std::ios_base&) ' is private
/usr/include/c++/4.0.0/iosfwd:55: error: within this context
/usr/include/c++/4.0.0/iosfwd: In copy constructor
'std::basic_ist ream<char, std::char_trait s<char::basic_i stream(const
std::basic_istr eam<char, std::char_trait s<char&)':
/usr/include/c++/4.0.0/iosfwd:61: warning: synthesized method
'std::basic_ios <char, std::char_trait s<char::basic_i os(const
std::basic_ios< char, std::char_trait s<char&)' first required here
a.cpp: In function 'int main(int, char**)':
a.cpp:10: warning: synthesized method 'std::basic_ist ream<char,
std::char_trait s<char::basic_i stream(const std::basic_istr eam<char,
std::char_trait s<char&)' first required here
a.cpp:10: error: no matching function for call to
'std::istream_i terator<char, char, std::char_trait s<char>,
ptrdiff_t>::ist ream_iterator(s td::basic_istre am<char,
std::char_trait s<char)'
/usr/include/c++/4.0.0/bits/stream_iterator .h:70: note: candidates are:
std::istream_it erator<_Tp, _CharT, _Traits,
_Dist>::istream _iterator(const std::istream_it erator<_Tp, _CharT,
_Traits, _Dist>&) [with _Tp = char, _CharT = char, _Traits =
std::char_trait s<char>, _Dist = ptrdiff_t]
/usr/include/c++/4.0.0/bits/stream_iterator .h:66: note:
std::istream_it erator<_Tp, _CharT, _Traits,
_Dist>::istream _iterator(std:: basic_istream<_ CharT, _Traits>&) [with
_Tp = char, _CharT = char, _Traits = std::char_trait s<char>, _Dist =
ptrdiff_t]
/usr/include/c++/4.0.0/bits/stream_iterator .h:62: note:
std::istream_it erator<_Tp, _CharT, _Traits, _Dist>::istream _iterator()
[with _Tp = char, _CharT = char, _Traits = std::char_trait s<char>,
_Dist = ptrdiff_t]
Now, I have discovered that if I change the program into the following,
then it compiles fine:
#include <iostream>
#include <fstream>
#include <iterator>
#include <algorithm>
using namespace std;
int main(int argc, char **argv)
{
istream *ifile = argc >= 2 ? new ifstream(argv[1]) : &cin;
copy(istream_it erator<char>(*i file),
istream_iterato r<char>(),
ostream_iterato r<char>(cout)) ;
return 0;
}
I know this works, but it would be nice to understand why the original
version does not work anyway.
Thank you for your help.
--
-kira
