I was wondering if you can stream directly from one stream to another. e.g.
which obviously didn't work on my compiler (g++).Code:ifstream f("somefile", ios::in); cout << f;
I know you can use rdbuf or getline or get.
I tried something called "tie" but that didn't work either:
So how do you go about doing this?Code:cout.tie(&ifstream);
Maybe this is something like what you want to do?
Code:# include <fstream> # include <iostream> # include <iomanip> # include <iterator> # include <algorithm> using namespace std; int main() { ifstream f("test.txt",ios::in); f >> noskipws; std::copy(istream_iterator<char>(f), istream_iterator<char>(), ostream_iterator<char>(cout, "")); return 0; }
The crows maintain that a single crow could destroy the heavens. Doubtless this is so. But it proves nothing against the heavens, for the heavens signify simply: the impossibility of crows.
If you're going to do that you might as well use rdbuf.
using namespace std;
std::copy(...);
Heh, just leave out the using namespace std; it is a poor habit anyway.
The ifstream, the cout and the iterators need an std:: then.
True Daved, but my point still stands, leave out using namespace std; That is only there so that old code written prestandard can still compile.
I personally always use std::, but use of the using directive here is pretty harmless and not the point of the code at all.
Nothing wrong with using rdbuf(), you know ...
All the buzzt!
CornedBee
"There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
- Flon's Law
So, I take it that there is no way to stream directly from stream to stream using the << operator? Well, the copy method was interesting enough so thanks folks.
>> So, I take it that there is no way to stream directly from stream to stream using the << operator?
There is using rdbuf, but you already knew that.
Perhaps I should look at the specifications for this, but I was always curious why you had to use function calls to do IO on streams.
Why won't
implicitly understand that I just want to dump the entire thing to cout?Code://f is an fstream cout << f;
Why do you need the function calls, like:
If anybody could throw me a few links explaining why this is so, I'd appreciate it.Code://assuming ss is any type of stream cout << ss.rdbuf(); //somestring would be a variable of type string cout << somestring.c_str();
it has to do with the fact << is actually an operator and the object cout has it overloaded accepting only a limited range of right-hand operands.
http://www.cplusplus.com/ref/iostrea...ratorltlt.html
one of them is a stream buffer
Originally Posted by brewbuck:
Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.
you could always overload the << operator yourself.
something like
but that doesn't really gain you much and could possibly cause an overload ambiguity (or maybe not, I'm just thinking aloud)Code:ostream &operator<<(ostream &os, ifstream &f) { os << f.rdbuf(); return os; }
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Free Compiler: Visual C++ 2005 Express
If you program in C++, you need Boost. You should also know how to use the Standard Library (STL). Want to make games? After reading this, I don't like WxWidgets anymore.Want to add some scripting to your App?
>> cout << somestring.c_str();
You don't need a function call there, there is an overload for the string class already:Perhaps you forgot to #include <string>. On some compilers the string class works for the most part but fails with operator<< if you don't include the proper header.Code:cout << somestring;
