std::filesystem::path::path
From cppreference.com
< cpp | filesystem | path
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 > path( const Source& source, format fmt = auto_format ); |
(5) | (since C++17) |
template< class InputIt > path( InputIt first, InputIt last, format fmt = auto_format ); |
(6) | (since C++17) |
template< class Source > path( const Source& source, const std::locale& loc, format fmt = auto_format ); |
(7) | (since C++17) |
template< class InputIt > path( InputIt first, InputIt last, const std::locale& loc, format fmt = auto_format ); |
(8) | (since C++17) |
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).
|
(since C++20) |
- 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).
Contents |
[edit] Parameters
p | - | a path to copy |
source | - | std::basic_string, std::basic_string_view, pointer to a 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).
|
[edit] Exceptions
2,4-8) May throw implementation-defined exceptions.
[edit] Notes
For portable pathname generation from Unicode strings, see |
(until C++20) |
|
(since C++20) |
[edit] 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"
[edit] 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 missing
|
added |
[edit] See also
(C++17)(deprecated in C++20) |
creates a path from a UTF-8 encoded source (function) |