NAME

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

LIBRARY

       The roken library (libroken, -lroken)

SYNOPSIS

       #include <parse_time.h>

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

       void
       print_time_table(FILE *f);

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

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

DESCRIPTION

       The  parse_time()  function converts the period of time specified 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.
       Numbers without explicit units are taken as being def_unit.

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

       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
             day
             week   seven days
             month  30 days
             year   365 days

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

RETURN VALUES

       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.

EXAMPLES

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

       int
       main(int argc, char **argv)
       {
           int i;
           int result;
           char buf[128];
           print_time_table(stdout);
           for (i = 1; i < argc; i++) {
               result = parse_time(argv[i], "second");
               if(result == -1) {
                   fprintf(stderr, "%s: parse error\n", argv[i]);
                   continue;
               }
               printf("--\n");
               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

BUGS

       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.

HEIMDAL                                         November 17, 2013                                  PARSE_TIME(3)