giving one line command that prints lots of lines - ostream?

I'm using cout to print lots of lines. But i want to put together them in one variable etc. Then , i want to print it.
I think i can do it with ostream but I cant do it . Is there anybody to give me an example use of ostream.

I want to use it such that:
x<< "hello" << endl;
x<< "mike" << endl;
x<< "how " << endl;
x<< "are" << endl;
x<< "you" << endl;

cout << x;
will print

hello
mike
how
are
you

How can i do it?
Thanks in advance

The quickest thing would probably be the use of a ostringstream

Code:

---

#include <sstream>

std::ostringstream os;
os << "hello\n";
os << "mike\n";
os << "how\n";
os << "are\n";
os << "you\n";

std::cout << os.str();

---

Another possibility could be to define a class X that is able to hold the values you want (but that would limit you in terms of usability of that class) and write operator<< for that class

Code:

---

struct X
{
    int i;
    // ...
};

std::ostream& operator<<(std::ostream& os, const X& x)
{
    os << x.i /* << other members... */ << std::endl;
    return os;
}

---

HTH
Richard

Quote:

---

Originally Posted by loves_oi

I'm using cout to print lots of lines. But i want to put together them in one variable etc. Then , i want to print it.
I think i can do it with ostream but I cant do it . Is there anybody to give me an example use of ostream.

---

std::cout has its own internal buffer, so it won't print everything you write directly. However, every time you write std::end, the buffer is flushed. You can write the string literal "\n" instead to avoid flushing the buffer.*

* Should read: "to avoid forcing the buffer to be flushed."

must be "std::endl"

Quote:

---

Originally Posted by D_Drmmr

std::cout has its own internal buffer, so it won't print everything you write directly. However, every time you write std::end, the buffer is flushed. You can write the string literal "\n" instead to avoid flushing the buffer.

---

correct me if I'm wrong, but you can't systematically prevent the stream to flush unless an ad hoc stream buffer is used ( whereas, as you said, you can force the stream to flush, of course ), or am I missing something ?

actually, as far as I can tell, the OP wants a way to "store" a set of cout statements in a single "variable", as suggested by RichardJ. Another alternative wth the bonus of delayed-evaluation (see below) could be somethng like:

Code:

---

#include <iostream>

template < class Fn >
struct stream_t { Fn f; stream_t( Fn const& f ): f(f) {} };

template < class Fn >
stream_t<Fn> stream( Fn f ) { return stream_t<Fn>( f ); }

template < class Fn >
std::ostream& operator<<( std::ostream& os, stream_t<Fn> st ) { st.f( os ); return os; }

int main()
{
        int x = 0;
        auto printed_x = [&]( std::ostream& os ) { os << '(' << x << ')'; };

        std::cout << stream(printed_x) << std::endl; // prints "(0)"
        x = 1;
        std::cout << stream(printed_x) << std::endl; // prints "(1)"
}

---

( note: I used a stream_t wrapper instead of type deduction to make the resulting operator<< the less intrusive as possible ... )

Quote:

---

Originally Posted by superbonzo

correct me if I'm wrong, but you can't systematically prevent the stream to flush unless an ad hoc stream buffer is used ( whereas, as you said, you can force the stream to flush, of course ), or am I missing something ?

---

Yes, I meant you can use "\n" to avoid forcing a flush. You cannot prevent the stream from flushing.