time/curr_time.c

This is time/curr_time.c (Listing 10-2, page 194), an example from the book, The Linux Programming Interface.

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currTime()

/* curr_time.c

   Implement our currTime() function.
*/
#include <time.h>
#include "curr_time.h"          /* Declares function defined here */

#define BUF_SIZE 1000

/* Return a string containing the current time formatted according to
   the specification in 'format' (see strftime(3) for specifiers).
   If 'format' is NULL, we use "%c" as a specifier (which gives the'
   date and time as for ctime(3), but without the trailing newline).
   Returns NULL on error. */

char *
currTime(const char *format)
{
    static char buf[BUF_SIZE];  /* Nonreentrant */
    time_t t;
    size_t s;
    struct tm *tm;

    t = time(NULL);
    tm = localtime(&t);
    if (tm == NULL)
        return NULL;

    s = strftime(buf, BUF_SIZE, (format != NULL) ? format : "%c", tm);

    return (s == 0) ? NULL : buf;
}

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