Sort an array of struct tm

I am currently creating a personal diary in C and I'd like to have the possibility to print the post sorted by date. I can extract the date using the struct tm but I don't know to sort the dates so that the most recent is on top. This is my whole function here :

void dateOrder() {
    FILE *postfile = fopen("post.txt", "r");

    int numofpost = getNumOfPost(postfile);
    int dates[numofpost];

    struct tm ptime;

    char *elt = malloc(5 * sizeof(char));
    char *dref = "Date";
    char *href = "Heure";
    char c = 'c';

    char *pseudo = malloc(20 * sizeof(char));
    int pseudolen = 0;

    rewind(postfile);

    while (!feof(postfile)) {

        fscanf(postfile, "%s", elt);

        if (strcmp(elt, dref) == 0) {
            fseek(postfile, 3, SEEK_CUR);
            fscanf(postfile, "%d/%d/%d", (int)&(ptime.tm_mday), (int)&(ptime.tm_mon), (int)&(ptime.tm_year));
        }

        if (strcmp(elt, href) == 0) {
            fseek(postfile, 3, SEEK_CUR);
            fscanf(postfile, "%d:%d", (int)&(ptime.tm_hour), (int)&(ptime.tm_min));
        }

        ptime.tm_year -= 1900;
        ptime.tm_mon -= 1;
        ptime.tm_sec = 0;
        ptime.tm_isdst = -1;
        int rep = mktime(&ptime);

        if (rep != -1) {
            dates[i++] = rep;
        }
    }

    insertsort(dates, sizeof(dates)/sizeof(dates[0]));

    for (int i = 0; i < numofpost; i++) {
        c = 'c';
        rewind(postfile);

        while (!feof(postfile) && c != 24) {

            fscanf(postfile, "%s", elt);

            if (strcmp(elt, "Pseudo") == 0) {
                fseek(postfile, 3, SEEK_CUR);
                fscanf(postfile, "%s", pseudo);
                pseudolen = strlen(pseudo);
            }

            if (strcmp(elt, dref) == 0) {

                fseek(postfile, 3, SEEK_CUR);
                fscanf(postfile, "%d/%d/%d", (int)&(ptime.tm_mday), (int)&(ptime.tm_mon), (int)&(ptime.tm_year));
            }

            if (strcmp(elt, href) == 0) {
                fseek(postfile, 3, SEEK_CUR);
                fscanf(postfile, "%d:%d", (int)&(ptime.tm_hour), (int)&(ptime.tm_min));
            }

            ptime.tm_year -= 1900;
            ptime.tm_mon -= 1;
            ptime.tm_sec = 0;
            ptime.tm_isdst = -1;
            int mkt = mktime(&ptime);

            if (mkt == dates[i]) {
                fseek(postfile, -39, SEEK_CUR);
                fseek(postfile, -pseudolen, SEEK_CUR);

                while (c != 24) {
                    c = fgetc(postfile);

                    if (c == 24)
                        continue;

                    printf("%c", c);
                }
            }
        }
    }

    fclose(postfile);   
}

And this is struct tm :

struct tm {
   int tm_sec;         /* seconds,  range 0 to 59          */
   int tm_min;         /* minutes, range 0 to 59           */
   int tm_hour;        /* hours, range 0 to 23             */
   int tm_mday;        /* day of the month, range 1 to 31  */
   int tm_mon;         /* month, range 0 to 11             */
   int tm_year;        /* The number of years since 1900   */
   int tm_wday;        /* day of the week, range 0 to 6    */
   int tm_yday;        /* day in the year, range 0 to 365  */
   int tm_isdst;       /* daylight saving time             */
 };