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     parse_time, print_time_table, unparse_time, unparse_time_approx, - parse
     and unparse time intervals


     The roken library (libroken, -lroken)


     #include <parse_time.h>

     parse_time(const char *timespec, const char *def_unit);

     print_time_table(FILE *f);

     unparse_time(int seconds, char *buf, size_t len);

     unparse_time_approx(int seconds, char *buf, size_t len);


     The parse_time() function converts a the period of time specified in into
     a number of seconds.  The timespec can be any number of 〈number unit〉
     pairs separated by comma and whitespace. The number can be negative.
     Number without explicit units are taken as being def_unit.

     The unparse_time() and unparse_time_approx() does the opposite of
     parse_time(), that is they take a number of seconds and express that as
     human readable string.  unparse_time produces an exact time, while
     unparse_time_approx restricts the result to only include one units.

     print_time_table() prints a descriptive list of available units on the
     passed file descriptor.

     The possible units include:
           second, s
           minute, m
           hour, h
           week   seven days
           month  30 days
           year   365 days

     Units names can be arbitrarily abbreviated (as long as they are unique).


     parse_time() returns the number of seconds that represents the expression
     in timespec or -1 on error.  unparse_time() and unparse_time_approx()
     return the number of characters written to buf.  if the return value is
     greater than or equal to the len argument, the string was too short and
     some of the printed characters were discarded.


     #include <stdio.h>
     #include <parse_time.h>

     main(int argc, char **argv)
         int i;
         int result;
         char buf[128];
         for (i = 1; i < argc; i++) {
             result = parse_time(argv[i], "second");
             if(result == -1) {
                 fprintf(stderr, "%s: parse error\n", argv[i]);
             printf("parse_time = %d\n", result);
             unparse_time(result, buf, sizeof(buf));
             printf("unparse_time = %s\n", buf);
             unparse_time_approx(result, buf, sizeof(buf));
             printf("unparse_time_approx = %s\n", buf);
         return 0;

     $ ./a.out "1 minute 30 seconds" "90 s" "1 y -1 s"
     1   year = 365 days
     1  month = 30 days
     1   week = 7 days
     1    day = 24 hours
     1   hour = 60 minutes
     1 minute = 60 seconds
     1 second
     parse_time = 90
     unparse_time = 1 minute 30 seconds
     unparse_time_approx = 1 minute
     parse_time = 90
     unparse_time = 1 minute 30 seconds
     unparse_time_approx = 1 minute
     parse_time = 31535999
     unparse_time = 12 months 4 days 23 hours 59 minutes 59 seconds
     unparse_time_approx = 12 months


     Since parse_time() returns -1 on error there is no way to parse "minus
     one second".  Currently "s" at the end of units is ignored. This is a
     hack for English plural forms. If these functions are ever localised,
     this scheme will have to change.