I am writing a program in a linux system where I have to find the newest modified file (ie: the most recent file which has been modified) based on the timestamp in my current directory.
In the example below, I have to look through all the files in the directory and find the one with the latest timestamp (i.e. File.txt).
/root/MyProgram <- Current Directory
-Test1.txt 25/10/2019 14:30:26
-TEST2.bin 15/01/2020 18:12:36
-Test3.bin 06/05/2021 08:45:10
-File.txt 06/12/2021 03:10:55
I am able to get the timestamp of each file in my current directory but I want a method to compare the two timestamps (compare both date and time).
void show_dir_content(char *path) {
struct dirent *dir;
struct stat statbuf;
char datestring[256];
struct tm *tm;
DIR *d = opendir(path);
if (d == NULL) {
return;
}
//
while ((dir = readdir(d)) != NULL) {
if (dir->d_type == DT_REG) {
char f_path[500];
char filename[256];
sprintf(filename, "%s", dir->d_name);
sprintf(f_path, "%s/%s", path, dir->d_name);
printf("filename: %s", filename);
printf(" filepath: %s\n", f_path);
if (stat(f_path, &statbuf) == -1) {
fprintf(stderr,"Error: %s\n", strerror(errno));
continue;
}
tm = gmtime(&statbuf.st_mtime);
time_t t1 = statbuf.st_mtime;
strftime(datestring, sizeof(datestring), " %x-%X", tm);
printf("datestring: %s\n", datestring);
}
if (dir->d_type == DT_DIR && strcmp(dir->d_name, ".") != 0 && strcmp(dir->d_name, "..") != 0) {
printf("directory: %s ", dir->d_name);
char d_path[500];
sprintf(d_path, "%s/%s", path, dir->d_name);
printf(" dirpath: %s\n", d_path);
show_dir_content(d_path);
}
}
closedir(d);
}
The timestamp for the last modification time is statbuf.st_mtime. The type is struct timespec, a structure with 2 members:
tv_sec, the number of seconds since Jan 1st, 1970 0:00:00 UTC,tv_nsec, a number of nanoseconds.You can compare 2 such timestamps this way:
// compare 2 timespecs:
// return -1 if t1 < t2, 0 if they are equal, 1 if t1 > t2
int compare_timespec(const struct timespec *t1, const struct timespec *t2) {
if (t1->tv_sec == t2->tv_sec)
return (t1->tv_nsec > t2->tv_nsec) - (t1->tv_nsec < t2->tv_nsec);
else
return (t1->tv_sec > t2->tv_sec) ? 1 : -1;
}