From cppreference.com
Defined in header
boolequivalent(conststd::filesystem::path&p1,conststd::filesystem::path&p2); (1) (since C++17)boolequivalent(conststd::filesystem::path&p1,conststd::filesystem::path&p2,std::error_code&ec)noexcept; (2) (since C++17)Checks whether the paths p1 and p2 resolve to the same file system entity.
If either p1 or p2 does not exist, an error is reported.
The non-throwing overload returns false on errors.
Parameters
p1, p2 - paths to check for equivalence ec - out-parameter for error reporting in the non-throwing overload Return value
true if the p1 and p2 refer to the same file or directory and their file status is the same. false otherwise.
Exceptions
Any overload not marked noexcept may throw
if memory allocation fails.
1) Throws
std::filesystem::filesystem_error
on underlying OS API errors, constructed with p1 as the first path argument, p2 as the second path argument, and the OS error code as the error code argument.
2) Sets a std::error_code& parameter to the OS API error code if an OS API call fails, and executes ec.
() if no errors occur.
Notes
Two paths are considered to resolve to the same file system entity if the two candidate entities the paths resolve to are located on the same device at the same location. For POSIX, this means that the st_dev and st_ino members of their POSIX
, obtained as if by POSIX
, are equal.
In particular, all hard links for the same file or directory are equivalent, and a symlink and its target on the same file system are equivalent.
Example
Run this code
#include<cstdint>#include<filesystem>#include<iostream>namespacefs=std::filesystem;intmain(){// hard link equivalencyfs::pathp1=".";fs::pathp2=fs::current_path();if(fs::equivalent(p1,p2))std::cout<<p1<<" is equivalent to "<<p2<<'\n';// symlink equivalencyfor(constfs::pathlib:{"/lib/libc.so.6","/lib/x86_64-linux-gnu/libc.so.6"}){try{p2=lib.parent_path()/fs::read_symlink(lib);}catch(std::filesystem::filesystem_errorconst&ex){std::cout<<ex.what()<<'\n';continue;}if(fs::equivalent(lib,p2))std::cout<<lib<<" is equivalent to "<<p2<<'\n';}}Possible output:
"." is equivalent to "/var/tmp/test" filesystem error: read_symlink: No such file or directory [/lib/libc.so.6] "/lib/x86_64-linux-gnu/libc.so.6" is equivalent to "/lib/x86_64-linux-gnu/libc-2.23.so" Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR Applied to Behavior as published Correct behavior
C++17 error condition specified incorrectly corrected See also