std::filesystem::directory_entry::exists

 

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功能特性测试宏(C++20)

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技术规范

符号索引

外部库

 

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::file_time_type filesystem::perms filesystem::perm_options filesystem::copy_options filesystem::directory_options
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::temp_directory_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
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::directory_entry

成员函数

directory_entry::directory_entry

修改器

directory_entry::operator=

directory_entry::assign

directory_entry::replace_filename

directory_entry::refresh

观察器

directory_entry::pathdirectory_entry::operator const path&

directory_entry::exists

directory_entry::is_block_file

directory_entry::is_character_file

directory_entry::is_directory

directory_entry::is_fifo

directory_entry::is_other

directory_entry::is_regular_file

directory_entry::is_socket

directory_entry::is_symlink

directory_entry::file_size

directory_entry::hard_link_count

directory_entry::last_write_time

directory_entry::statusdirectory_entry::symlink_status

directory_entry::operator==directory_entry::operator!=directory_entry::operator<directory_entry::operator>directory_entry::operator<=directory_entry::operator>=directory_entry::operator<=> (C++20 前)(C++20 前)(C++20 前)(C++20 前)(C++20 前)(C++20)

非成员函数

operator<<

 

bool exists()const;	(1)	(C++17 起)
bool exists(std::error_code& ec )constnoexcept;	(2)	(C++17 起)

检查所指的对象是否存在。各自等效于返回：

1)std::filesystem::exists(status())。

2)std::filesystem::exists(status(ec))。

注意，status() 将跟随符号链接到其目标。

参数

ec

-

不抛出重载中报告错误的输出形参

返回值

若被指代文件系统对象存在则为 true。

异常

若内存分配失败，则任何不标记为 noexcept 的重载可能抛出 std::bad_alloc 。

1) 抛出 std::filesystem::filesystem_error，构造时以 p 为第一路径实参并以OS 错误码为错误码实参。

2) 若 OS API 调用失败，则设置 std::error_code& 为 OS API 错误码，而未发生错误时则执行 ec.clear()。

示例

运行此代码

#include <filesystem>#include <iostream>   int main(){for(autoconst str:{"/usr/bin/cat", "/usr/bin/mouse", "/usr/bin/python", "/usr/bin/bison", "/usr/bin/yacc", "/usr/bin/c++", }){std::filesystem::directory_entry entry{str};   std::cout<<"directory entry "<< entry <<(entry.exists()?" exists\n":" does not exist\n");}}

可能的输出：

// Output on a POSIX system: directory entry "/usr/bin/cat" exist directory entry "/usr/bin/mouse" does not exist directory entry "/usr/bin/python" exists directory entry "/usr/bin/bison" exists directory entry "/usr/bin/yacc" does not exist directory entry "/usr/bin/c++" exists

参阅

exists (C++17)

检查路径是否指代既存的文件系统对象 (函数)