std::filesystem::path::path(3)

NAME
std::filesystem::path::path - std::filesystem::path::path

Synopsis
   path() noexcept; (1) (since C++17)
   path( const path& p ); (2) (since C++17)
   path( path&& p ) noexcept; (3) (since C++17)
   path( string_type&& source, format fmt = auto_format ); (4) (since C++17)
   template< class Source > (5) (since C++17)
   path( const Source& source, format fmt = auto_format );
   template< class InputIt > (6) (since C++17)
   path( InputIt first, InputIt last, format fmt = auto_format );
   template< class Source >
   path( const Source& source, const std::locale& loc, format fmt = (7) (since C++17)
   auto_format );
   template< class InputIt >
   path( InputIt first, InputIt last, const std::locale& loc, format (8) (since C++17)
   fmt = auto_format );
   Constructs a new path object.
   1) Constructs an empty path.
   2) Copy constructor. Constructs a path whose pathname, in both native and generic
   formats, is the same as that of p.
   3) Move constructor. Constructs a path whose pathname, in both native and generic
   formats, is the same as that of p, p is left in valid but unspecified state.
   4-6) Constructs the path from a character sequence (format interpreted as specified
   by fmt) provided by source (4,5), which is a pointer or an input iterator to a
   null-terminated character/wide character sequence, an std::basic_string or an
   std::basic_string_view, or represented as a pair of input iterators [first, last)
   (6). Any of the character types char,
   char8_t,
   (since C++20)char16_t, char32_t, wchar_t is allowed, and the method of conversion to
   the native character set depends on the character type used by source.
     * If the source character type is char, the encoding of the source is assumed to
       be the native narrow encoding (so no conversion takes place on POSIX systems).
     * If the source character type is char8_t, conversion from UTF-8 to (since C++20)
       native filesystem encoding is used.
     * If the source character type is char16_t, conversion from UTF-16 to native
       filesystem encoding is used.
     * If the source character type is char32_t, conversion from UTF-32 to native
       filesystem encoding is used.
     * If the source character type is wchar_t, the input is assumed to be the native
       wide encoding (so no conversion takes places on Windows).
   7,8) Constructs the path from a character sequence (format interpreted as specified
   by fmt) provided by source (7), which is a pointer or an input iterator to a
   null-terminated character sequence, an std::string, an std::string_view, or
   represented as a pair of input iterators [first, last) (8). The only character type
   allowed is char. Uses loc to perform the character encoding conversion. If
   value_type is wchar_t, converts from to wide using the std::codecvt<wchar_t, char,
   std::mbstate_t> facet of loc. Otherwise, first converts to wide using the
   std::codecvt<wchar_t, char, std::mbstate_t> facet and then converts to filesystem
   native character type using std::codecvt<wchar_t,value_type> facet of loc.
   (5) and (7) participate in overload resolution only if Source and path are not the
   same type, and either:
     * Source is a specialization of std::basic_string or std::basic_string_view, or
     * std::iterator_traits<std::decay_t<Source>>::value_type is valid and denotes a
       possibly const-qualified encoding character type (char,
       char8_t,
       (since C++20)char16_t, char32_t, or wchar_t).

Parameters
   p - a path to copy
                 std::basic_string, std::basic_string_view, pointer to a
   source - null-terminated character string, or input iterator with a character
                 value type that points to a null-terminated character sequence (the
                 character type must be char for overload (7))
   first, last - pair of LegacyInputIterators that specify a character sequence
   fmt - enumerator of type path::format which specifies how pathname format is
                 to be interpreted
   loc - locale that defines encoding conversion to use

Type requirements
   -
   InputIt must meet the requirements of LegacyInputIterator.
   -
   The value type of InputIt must be one of the character types char, wchar_t,
   char8_t,
   (since C++20)char16_t and char32_t to use the overload (6).
   -
   The value type of InputIt must be char to use the overload (8).

Exceptions
   2,4-8) May throw implementation-defined exceptions.

Notes
   For portable pathname generation from Unicode strings, see u8path. (until C++20)
   path constructor supports creation from UTF-8 string when the source (since C++20)
   is a sequence of char8_t.

Example
// Run this code
 #include <filesystem>
 #include <iostream>
 namespace fs = std::filesystem;
 int main()
 {
     fs::path p1 = "/usr/lib/sendmail.cf"; // portable format
     fs::path p2 = "C:\\users\\abcdef\\AppData\\Local\\Temp\\"; // native format
     fs::path p3 = U"D:/猫.txt"; // UTF-32 string
     fs::path p4 = u8"~/狗.txt"; // UTF-8 string
     std::cout << "p1 = " << p1 << '\n'
               << "p2 = " << p2 << '\n'
               << "p3 = " << p3 << '\n'
               << "p4 = " << p4 << '\n';
 }

Output:
 p1 = "/usr/lib/sendmail.cf"
 p2 = "C:\\users\\abcdef\\AppData\\Local\\Temp\\"
 p3 = "D:/猫.txt"
 p4 = "~/狗.txt"
   Defect reports
   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.
      DR Applied to Behavior as published Correct behavior
   LWG 3244 C++17 constraint that Source cannot be path was added
                       missing

See also
   u8path creates a path from a UTF-8 encoded source
   (C++17)(deprecated in C++20) (function)