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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. Other- wise, 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 rd- state(), 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 rd- buf 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 http://cppreference.com 2022.07.31 std::basic_ios::copyfmt(3)
NAME | Synopsis | Parameters | Return value | Notes | Example | Output:
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