如何在 OS X/C 中获取文件的最后修改时间？

Question

I have the following code:

struct stat info;
stat("/Users/john/test.txt", &info);
printf("%s\n", ctime(&info.st_mtimespec));

in which I am trying to get the last modified time of the file as displayed in the ls -l command in the format:

Jan 29 19:39

Unfortunately, above code doesn't work.I get the following error message on xcode:

Conflicting types for ctime

How can I fix it ? If there any alternative approaches to get the time in format mentioned, please do mention.

Answer 1

Checking on struct stat 's declaration you'll see that st_mtimespec must be st_mtime .

Then, basing on this question , I rearranged your code like this:

struct stat info;
struct tm* tm_info;
char buffer[16];

stat("/Users/john/test.txt", &info);
tm_info = localtime(&info.st_mtime);
strftime(buffer, sizeof(buffer), "%b %d %H:%M", tm_info);

printf("%s\n", buffer);

Hope it helps.

Answer 2

I believe this is what you are looking for:

#include <sys/stat.h>
#include <time.h>

int main(int argc, char *argv[])
{
    struct stat info;
    stat("sample.txt", &info);
    printf("%.12s\n", 4+ctime(&info.st_mtimespec));
    return 0;
}

Output( same as time field of ls -l ):

Feb  4 00:43

(This was for a random file on my computer).

Answer 3

does your code have:

#include <time.h>

also, the ctime() function expects the passed parameter to be a POINTER to a time_t .

Here is the struct pointed to by the stat() function:

          struct stat {
           dev_t     st_dev;     /* ID of device containing file */
           ino_t     st_ino;     /* inode number */
           mode_t    st_mode;    /* protection */
           nlink_t   st_nlink;   /* number of hard links */
           uid_t     st_uid;     /* user ID of owner */
           gid_t     st_gid;     /* group ID of owner */
           dev_t     st_rdev;    /* device ID (if special file) */
           off_t     st_size;    /* total size, in bytes */
           blksize_t st_blksize; /* blocksize for filesystem I/O */
           blkcnt_t  st_blocks;  /* number of 512B blocks allocated */
           time_t    st_atime;   /* time of last access */
           time_t    st_mtime;   /* time of last modification */
           time_t    st_ctime;   /* time of last status change */
       };

Notice that none of the fields are a st_mtimespec

perhaps you meant st_mtime

Note: your running OS-X and I'm running linux, but the OS-X should have the very same definitions of field names.