std::filesystem::path::path
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< cpp | filesystem | path
C++
Feature test macros (C++20)
Concepts library (C++20)
Metaprogramming library (C++11)
Ranges library (C++20)
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
Filesystem library
std::filesystem::path
Path decomposition Non-member functions
Helper classes
path::path
(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)
(C++26)
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)
path( const Source& source, format fmt = auto_format );
template< class InputIt >
path( InputIt first, InputIt last, format fmt = auto_format );
(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 = auto_format );
(7)
(since C++17)
path( const Source& source, const std::locale & loc, format fmt = auto_format );
template< class InputIt >
path( InputIt first, InputIt last, const std::locale & loc, format fmt = auto_format );
(8)
(since C++17)
path( InputIt first, InputIt last, const std::locale & loc, format 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 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:
-
Sourceis 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).
[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 u8path.
path constructor supports creation from UTF-8 string when the source is a sequence of char8_t.
[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 |