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std::filesystem::directory_entry::last_write_time

From cppreference.com
 
 
 
 
std::filesystem::file_time_type last_write_time() const;
std::filesystem::file_time_type last_write_time( std::error_code& ec ) const noexcept;
(since C++17)

If the last modification time is cached in this directory_entry, returns the cached value. Otherwise, returns std::filesystem::last_write_time(path()) or std::filesystem::last_write_time(path(), ec), respectively.

Contents

[edit] Parameters

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

[edit] Return value

The last modification time for the referred-to filesystem object

[edit] Exceptions

The overload that does not take a std::error_code& parameter throws 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. The overload taking a std::error_code& parameter sets it to the OS API error code if an OS API call fails, and executes ec.clear() if no errors occur. Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.

[edit] Example

#include <filesystem>
#include <iostream>
#include <string>
#include <chrono>
#include <ctime>
 
std::string to_string(std::filesystem::file_time_type const& ftime) {
    std::time_t cftime = std::chrono::system_clock::to_time_t(
        std::chrono::file_clock::to_sys(ftime));
    std::string str = std::asctime(std::localtime(&cftime));
    str.pop_back();  // rm the trailing '\n' put by `asctime`
    return str;
}
 
int main() {
    auto dir = std::filesystem::current_path();
    using Entry = std::filesystem::directory_entry;
    for (Entry const& entry : std::filesystem::directory_iterator(dir)) {
        std::cout << to_string(entry.last_write_time())
                  << " : " << entry.path().filename() << '\n';
    }
}

Possible output:

Sat Aug 21 07:39:13 2021 : "main.cpp"
Sat Aug 21 07:39:16 2021 : "a.out"

[edit] See also

gets or sets the time of the last data modification
(function) [edit]