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std::filesystem::path::path

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< cpp‎ | filesystem‎ | path
 
C++
 
Filesystem library
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Functions
File types
 
std::filesystem::path
Member types
Member constants
Member functions
Path decomposition
Non-member functions
(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)
Helper classes
 
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).
  • If the source character type is char8_t, conversion from UTF-8 to native filesystem encoding is used.
(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:

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 u8path.

(until C++20)

path constructor supports creation from UTF-8 string when the source is a sequence of char8_t.

(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) [edit]
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