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std::filesystem::directory_entry::exists(3) C++ Standard Libary std::filesystem::directory_entry::exists(3)

NAME

std::filesystem::directory_entry::exists - std::filesystem::directory_entry::exists

Synopsis


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


Checks whether the pointed-to object exists. Effectively returns:


1) std::filesystem::exists(status()),
2) std::filesystem::exists(status(ec)).


Note that status() follows symlinks to their targets.

Parameters


ec - out-parameter for error reporting in the non-throwing overload

Return value


true if the referred-to filesystem object exists.

Exceptions


Any overload not marked noexcept may throw std::bad_alloc if memory allocation
fails.


1) Throws std::filesystem::filesystem_error on underlying OS API errors, constructed
with p as the first 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.clear() if no errors occur.

Example

// Run this code


#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");
}
}

Possible output:


// 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

See also


exists checks whether path refers to existing file system object
(C++17) (function)

2024.06.10 http://cppreference.com