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#### regex_format (Deprecated)

The algorithm `regex_format` is deprecated; new code should use `match_results<>::format` instead. Existing code will continue to compile, the following documentation is taken from the previous version of Boost.Regex and will not be further updated:

##### Algorithm regex_format

    #include <boost/regex.hpp>

The algorithm `regex_format` takes the results of a match and creates a new string based upon a format string, `regex_format` can be used for search and replace operations:

    template <class OutputIterator, class iterator, class Allocator, class charT>
    OutputIterator regex_format(OutputIterator out,
                               const match_results<iterator, Allocator>& m,
                               const charT* fmt,
                               match_flag_type flags = 0);
    template <class OutputIterator, class iterator, class Allocator, class charT>
    OutputIterator regex_format(OutputIterator out,
                               const match_results<iterator, Allocator>& m,
                               const std::basic_string<charT>& fmt,
                               match_flag_type flags = 0);

The library also defines the following convenience variation of `regex_format`, which returns the result directly as a string, rather than outputting to an iterator.

| Note
This version may not be available, or may be available in a more limited form, depending upon your compilers capabilities

    template <class iterator, class Allocator, class charT>
    std::basic_string<charT> regex_format
                                     (const match_results<iterator, Allocator>& m,
                                     const charT* fmt,
                                     match_flag_type flags = 0);

    template <class iterator, class Allocator, class charT>
    std::basic_string<charT> regex_format
                                     (const match_results<iterator, Allocator>& m,
                                     const std::basic_string<charT>& fmt,
                                     match_flag_type flags = 0);

Parameters to the main version of the function are passed as follows:

Parameter | Description
--- | ---
`OutputIterator out` | An output iterator type, the output string is sent to this iterator. Typically this would be a std::ostream_iterator.
`const match_results<iterator, Allocator>& m` | An instance of `match_results` obtained from one of the matching algorithms above, and denoting what matched.
`const charT* fmt` | A format string that determines how the match is transformed into the new string.
`unsigned flags` | Optional flags which describe how the format string is to be interpreted.

Format flags are described under `match_flag_type`.

The format string syntax (and available options) is described more fully under format strings.