operator<<,>>(std::filesystem::path)

 

C++

语言

标准库头文件

自立与有宿主实现

具名要求

语言支持库

概念库 (C++20)

诊断库

工具库

字符串库

容器库

迭代器库

范围库 (C++20)

算法库

数值库

本地化库

输入/输出库

文件系统库 (C++17)

正则表达式库 (C++11)

原子操作库 (C++11)

线程支持库 (C++11)

技术规范

 

文件系统库

类
filesystem::path filesystem::filesystem_error filesystem::directory_entry filesystem::directory_iterator filesystem::recursive_directory_iterator filesystem::file_status	filesystem::space_info filesystem::file_type filesystem::perms filesystem::perm_options filesystem::copy_options filesystem::directory_options filesystem::file_time_type
函数
filesystem::absolute filesystem::canonicalfilesystem::weakly_canonical filesystem::relativefilesystem::proximate filesystem::copy filesystem::copy_file filesystem::copy_symlink filesystem::create_directory filesystem::create_directories filesystem::create_hard_link filesystem::create_symlink filesystem::create_directory_symlink filesystem::current_path	filesystem::exists filesystem::equivalent filesystem::file_size filesystem::hard_link_count filesystem::last_write_time filesystem::permissions filesystem::read_symlink filesystem::remove filesystem::remove_all filesystem::rename filesystem::resize_file filesystem::space filesystem::status filesystem::symlink_status filesystem::temp_directory_path
文件类型
filesystem::is_block_file filesystem::is_character_file filesystem::is_directory filesystem::is_empty filesystem::status_known	filesystem::is_fifo filesystem::is_other filesystem::is_regular_file filesystem::is_socket filesystem::is_symlink

 

std::filesystem::path

常量
path::native_formatpath::generic_formatpath::auto_format
成员函数
path::path path::~path path::operator= path::assign path::appendpath::operator /= path::concatpath::operator += path::clear path::make_preferred path::remove_filename path::replace_filename path::replace_extension path::swap path::compare path::beginpath::end	path::c_strpath::nativepath::operator string_type path::stringpath::u8stringpath::u16stringpath::u32stringpath::wstring path::generic_stringpath::generic_u8stringpath::generic_u16stringpath::generic_u32stringpath::generic_wstring path::lexically_normalpath::lexically_relativepath::lexically_proximate
路径分解
path::root_name path::root_directory path::root_path path::relative_path path::parent_path path::filename path::stem path::extension path::empty	path::has_root_pathpath::has_root_namepath::has_root_directorypath::has_relative_pathpath::has_parent_pathpath::has_filenamepath::has_stempath::has_extension path::is_absolutepath::is_relative
非成员函数
swap(path)
hash_value
operator==operator!=operator<operator<=operator>operator>=operator<=> (C++20 前)(C++20 前)(C++20 前)(C++20 前)(C++20 前)(C++20)
operator/
operator<<operator>>
u8path

 

template< class CharT, class Traits > friend std::basic_ostream<CharT,Traits>&     operator<<( std::basic_ostream<CharT,Traits>& os, const path& p );	(1)	(C++17 起)
template< class CharT, class Traits > friend std::basic_istream<CharT,Traits>&     operator>>( std::basic_istream<CharT,Traits>& is, path& p );	(2)	(C++17 起)

进行路径 p 上的流输入或输出。使用 std::quoted ，使得之后从流输入运算符读取时空格不导致截断。

这些函数模板对通常无限定或有限定查找不可见，而只能在 std::filesystem::path 为参数的关联类时由实参依赖查找找到。这在 using namespace std::filesystem; using 指令存在时阻止不想要的转换。

参数

os	-	要进行输出的流
is	-	要进行输入的流
p	-	要插入或释出的路径

返回值

1) os

2) is

异常

可能抛出实现定义的异常。

可能的实现

版本一
template< class CharT, class Traits > friend std::basic_ostream<CharT,Traits>& operator<<( std::basic_ostream<CharT,Traits>& os, const path& p ) { os << std::quoted(p.string<CharT,Traits>()); return os; }
版本二
template< class CharT, class Traits > friend std::basic_istream<CharT,Traits>& operator>>( std::basic_istream<CharT,Traits>& is, path& p ) { std::basic_string<CharT, Traits> t; is >> std::quoted(t); p = t; return is; }

示例

运行此代码

#include <iostream>
#include <filesystem>
int main()
{
    std::cout << std::filesystem::current_path() << '\n';
    std::cout << std::filesystem::temp_directory_path() << '\n';
}

可能的输出：

"/home/user"
"/tmp"

缺陷报告

下列更改行为的缺陷报告追溯地应用于以前出版的 C++ 标准。

DR	应用于	出版时的行为	正确行为
LWG 2989	C++17	允许在 using 指令存在时插入任何能转换到 path 的表达式	使之为隐藏的友元