how do i read files in a directory according to their modification time in c++ on windows

Question

Currently I am using dirent.h to iterativly access files in a directory and its sub-directories. It accesses them according to their file names (alphabetically). For some reason I want to access the subdirectories and the files according to their modification time (with the latest modified file being accessed at last). Is it possible to do so?

I am thinking to first traverse through the directories and create a sorted list of the files according to their modification time and use this list to read them accordingly. But I was hoping if there is a better way.

Your initial thinking seems like a good plan. Try it and see how it works out. — Some programmer dude, Dec 03 '19 at 08:23
You don't have much choice here other than doing the sorting yourself. Actualy the order isn't even guaranteed to be alphabetical, read [this SO article](https://stackoverflow.com/questions/8977441/does-readdir-guarantee-an-order) — Jabberwocky, Dec 03 '19 at 09:22

gr8_chi · Accepted Answer · 2019-12-14T11:11:05.850

Based on my first thinking and as per the suggestion in the comments.

#include<dirent.h>

typedef struct files {
long long mtime;
string file_path;
bool operator<(const files &rhs)const {
    return mtime < rhs.mtime;
}
}files;

using namespace std;
vector<struct files> files_list;

    void build_files_list(const char *path)  {
    struct dirent *entry;
    DIR *dp;
    if (dp = opendir(path)) {
        struct _stat64 buf;
        while ((entry = readdir(dp))){
            std::string p(path);
            p += "\\";
            p += entry->d_name;
            if (!_stat64(p.c_str(), &buf)){
                if (S_ISREG(buf.st_mode)){
                    files new_file;
                    new_file.mtime = buf.st_mtime;
                    new_file.file_path = entry->d_name;
                    files.push_back(new_file);
                }

            if (S_ISDIR(buf.st_mode) &&
                // the following is to ensure we do not dive into directories "." and ".."
                strcmp(entry->d_name, ".") && strcmp(entry->d_name, "..")){
                //do nothing
            }
        }
    }
    closedir(dp);
   }
   else{
       printf_s("\n\tERROR in openning dir %s\n\n\tPlease enter a correct 
        directory", path);
   }
}

void main(){
    char *dir_path="dir_path";
    build_files_list(dir_path);
    sort(files_list.begin(), files_list.end());
    //the rest of things to do
}

how do i read files in a directory according to their modification time in c++ on windows

1 Answers1