Re: I got a strange error message when using fstream!

From:
=?ISO-8859-1?Q?Daniel_Kr=FCgler?= <daniel.kruegler@googlemail.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Mon, 31 Mar 2008 10:43:04 CST
Message-ID:
<c137690d-15ba-46f2-b483-f846545d2dda@y21g2000hsf.googlegroups.com>
On 31 Mrz., 11:31, Wader <WaderC...@gmail.com> wrote:

#include <fstream>
#include <iostream>
#include <vector>
using namespace std;

class MyObj {
public:
        int data;
        ifstream in;

};

typedef std::vector<MyObj> MyObjVector;

int main(int arc, char* argv[]) {
     MyObjVector myVector;

     MyObj obj;
     obj.data = 10;
     obj.in.open("test.txt");

     myVector.push_back(obj);
}

In the code above, I want to use a vector of class MyObj, which have a
ifstream object, but I got a message says that I can't access the
private memeber of ios_base, both in MinGW and Visual C++, but if a
commented the line
    myVector.push_back(obj);
all thing is OK, can't any one help me!


std::vector requires that any feasible element type (value type) must
be CopyConstructible (and Assignable). This is a general Container
requirement of the current C++ standard, see
[lib.container.requirements]/3.

The member in of type std::ifstream does not fulfill this
requirement,
which follows by implication, because it's base class basic_ios is
not.

One possible workaround for you might be to use a
boost::shared_ptr<ifstream> instead and to use the free store ("new")
to
allocate the stream.

HTH & Greetings from Bremen,

Daniel Kr?gler

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