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std::basic_ios::copyfmt(3) | C++ Standard Libary | std::basic_ios::copyfmt(3) |
NAME¶
std::basic_ios::copyfmt - std::basic_ios::copyfmt
Synopsis¶
basic_ios& copyfmt(const basic_ios& other);
If other refers to the same object as *this, has no effects. Otherwise,
copies the
state of the stream other into *this. This is done in the following
sequence:
1) Calls every callback registered by register_callback() passing erase_event
as
parameter
2) Copies all member objects from other to *this except for rdstate(), the
exception
mask, and rdbuf(). In particular, makes copies of the locale, the formatting
flags,
the contents of the arrays std::ios_base::iword and std::ios_base::pword (but
not
the iword and pword pointers themselves), the callbacks, and the tied stream.
3) Calls every callback registered by register_callback() passing
copyfmt_event as
parameter
4) Copies the exception mask from other to *this as if by calling
exceptions(other.exceptions())
Parameters¶
other - another stream to use as source
Return value¶
*this
Notes¶
The second pass through the callbacks may be used to deep-copy
the user-defined
objects pointed to by the pointers in std::ios_base::pword
copyfmt() may be used to save and restore the state of a stream. Boost
provides a
more fine-grained I/O state savers library for the same purpose.
Example¶
makes the std::ofstream object "out" behave exactly
like std::cout, including
formatting, tie() to std::cin, etc.
// Run this code
#include <iostream>
#include <fstream>
int main()
{
std::ofstream out;
out.copyfmt(std::cout); // copy everything except rdstate and rdbuf
out.clear(std::cout.rdstate()); // copy rdstate
out.basic_ios<char>::rdbuf(std::cout.rdbuf()); // share the buffer
out << "Hello, world\n";
}
Output:¶
Hello, world
2022.07.31 | http://cppreference.com |