How can I change my print output? (System Programming and C)

Question

I wrote some code to display the last modified time and file names. My code compiles, but I need to change the format of the timestamp

What I want is:
Jul 17 12:12 2013 2-s.txt
Jul 17 12:12 2013 3-s.txt

What I'm getting now is:
Wed Jul 17 12:24:48 2013
2-s.txt
Wed Jul 17 12:24:48 2013
3-s.txt

Can someone take a look at my code below and give me some suggestions on how to fix it? Thank you!!!

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/utsname.h>
#include <ctype.h>
#include <string.h>
#include <ar.h>
#include <getopt.h>
#include <time.h>
#include <utime.h>

int main (int argc, char **argv)
{
    FILE *fp;
    size_t readNum;
    long long tot_file_size, cur_file_size;
    struct stat fileStat;
    struct ar_hdr my_ar;
    struct tm fileTime;
    struct utimbuf *fileTime2;

    //open the archive file (e.g., hw.a)
    fp = fopen(argv[1], "r");
    if (fp == NULL)
    {
        perror("Error opening the file\n");
        exit(-1);
    }

    //size of the archive file

     fseek(fp, 0, SEEK_END);
     tot_file_size =ftell(fp);
     rewind(fp);


    //read data into struct
    fseek(fp, strlen(ARMAG), SEEK_SET);     //skip the magic string



    while (ftell(fp) < tot_file_size - 1)
    {
        readNum = fread(&my_ar, sizeof(my_ar), 1, fp);

        if (stat(argv[1], &fileStat) == -1) {
            perror("stat");
            exit(EXIT_FAILURE);     //change from EXIT_SUCCESS to EXIT_FAILURE
        }

        if ((fileStat.st_mode & S_IFMT) == S_IFREG)
        {
            printf("%s", ctime(&fileStat.st_mtime));
            printf("%.*s", 15, my_ar.ar_name);
        }

        cur_file_size = atoll(my_ar.ar_size);

        if (fseek(fp, cur_file_size, SEEK_CUR) != 0)
        {
            perror("You have an error.\n");
            exit(-1);
        }

    }

    fclose(fp);

    return 0;
}

score 1 · Accepted Answer · answered Jul 19 '13 at 05:58

1

Once you have your time in a struct tm you can use strftime

#include <stdio.h>
#include <string.h>
#include <time.h>

int main()
{
  struct tm *tp;
  time_t t;
  char s[80];

  t = time(NULL);
  tp = localtime(&t);
  strftime(s, 80, "%b %d %H:%M %Y", tp);
  strcat(s, " 2-s.txt");
  printf("%s\n", s);
  return 0;
}

output:

Jul 19 07:57 2013 2-s.txt

answered Jul 19 '13 at 05:58

David Ranieri

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Thank you so much for the tips! I notice that you use local time. I need to use the last modified time of the file. Is there a way we can edit that (for example, remove Wed in the front)? – user2203774 Jul 19 '13 at 06:07
Check [this](http://stackoverflow.com/questions/13542345/how-to-convert-st-mtime-which-get-from-stat-function-to-string-or-char) – David Ranieri Jul 19 '13 at 06:22

How can I change my print output? (System Programming and C)

1 Answers1