...one of the most highly
regarded and expertly designed C++ library projects in the
world. — Herb Sutter and Andrei
Format strings are used by the algorithm
regex_replace and by
match_results<>::format, and are used to transform
one string into another.
There are three kind of format string: Sed, Perl and Boost-Extended.
Alternatively, when the flag
is passed to one of these functions, then the format string is treated as a
string literal, and is copied unchanged to the output.