It is used to fing arrow character and returns the transformation of c to its equivalent using the ctype::narrow facet of the locale object currently imbued in the stream, if such an equivalence exists, or dfault otherwise.
This function is designed for instantiations of basic_ios that use a different (wider) character type: see basic_ios::narro.
Following is the declaration for ios::narrow function.
char narrow (char c, char dfault) const;
c − Character to be "narrowed".
dfault − Character returned if c has no standard equivalent.
The narrow equivalent of c, if any. Otherwise, it returns dfault.
Strong guarantee − if an exception is thrown, there are no changes in the stream.
Accesses the stream object.
Concurrent access to the same stream object may cause data races.