tmp/tmpb4fn858x/{from.md → to.md}
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| 1 |
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### Overview <a id="iostream.forward.overview">[[iostream.forward.overview]]</a>
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The class template specialization `basic_ios<charT, traits>` serves as a
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virtual base class for the class templates `basic_istream`,
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`basic_ostream`, and class templates derived from them. `basic_iostream`
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is a class template derived from both `basic_istream<charT, traits>` and
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`basic_ostream<charT, traits>`.
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The class template specialization `basic_streambuf<charT, traits>`
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serves as a base class for class templates `basic_stringbuf` and
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`basic_filebuf`.
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The class template specialization `basic_istream<charT, traits>` serves
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as a base class for class templates `basic_istringstream` and
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`basic_ifstream`.
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The class template specialization `basic_ostream<charT, traits>` serves
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as a base class for class templates `basic_ostringstream` and
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`basic_ofstream`.
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The class template specialization `basic_iostream<charT, traits>` serves
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as a base class for class templates `basic_stringstream` and
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`basic_fstream`.
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Other *typedef-name*s define instances of class templates specialized
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for `char` or `wchar_t` types.
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Specializations of the class template `fpos` are used for specifying
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file position information.
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The types `streampos` and `wstreampos` are used for positioning streams
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specialized on `char` and `wchar_t` respectively.
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[*Note 1*:
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This synopsis suggests a circularity between `streampos` and
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`char_traits<char>`. An implementation can avoid this circularity by
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substituting equivalent types. One way to do this might be
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``` cpp
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template<class stateT> class fpos { ... }; // depends on nothing
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using _STATE = ... ; // implementation private declaration of stateT
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using streampos = fpos<_STATE>;
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template<> struct char_traits<char> {
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using pos_type = streampos;
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}
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```
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— *end note*]
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