std::basic_ios<CharT,Traits>::copyfmt - cppreference.com (original) (raw)

| 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. 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.

2. Copies the exception mask from other to *this as if by calling exceptions(other.exceptions()).

[edit] Parameters

[edit] Return value

*this

[edit] 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.

[edit] Example

Makes the std::ofstream object "out" behave exactly like std::cout, including formatting, tie() to std::cin, etc.

Possible output:

Hello, world

1. out2.flags(): 00000000000000000001000000000010
2. cout.flags(): 00000000000000000001000000000010
3. cout.flags(): 00000000000000000001000000001111
4. out2.flags(): 00000000000000000001000000001111

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.