std::filesystem::directory_entry::exists

 

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符號索引

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類
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
函式
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
檔案型別
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

成員函式

directory_entry::directory_entry

修改器

directory_entry::operator=

directory_entry::assign

directory_entry::replace_filename

directory_entry::refresh

觀察器

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<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

非成員函式

operator<<

 

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

檢查指向的物件是否存在。實際上返回

1) std::filesystem::exists(status())，

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

注意 status() 會跟隨符號連結到其目標。

引數

ec

-

非丟擲過載中用於錯誤報告的出參

返回值

true，如果引用的檔案系統物件存在。

異常

任何未標記為 noexcept 的過載都可能在記憶體分配失敗時丟擲 std::bad_alloc。

1) 在底層 OS API 錯誤時丟擲 std::filesystem::filesystem_error，構造時以 p 作為第一個路徑引數，OS 錯誤碼作為錯誤碼引數。

2) 如果 OS API 呼叫失敗，則將 std::error_code& 引數設定為 OS API 錯誤碼；如果沒有發生錯誤，則執行 ec.clear()。

示例

執行此程式碼

#include <filesystem>
#include <iostream>
 
int main()
{
    for (auto const 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");
    }
}

可能的輸出

// 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

參閱

exists (C++17)

檢查路徑是否引用現有檔案系統物件 (函式)