Section for Week 5, Tuesday, 2/9/99

1.  Hand back exams, go over solutions & grading. 
    Midterm #1 histogram:
    1 6
    2 03344556789999
    3 0122233445666678888899
    4 00111112222233344445667779

2.  Date & Time functions:
    time() -- will return the number of seconds since 1/1/1970
    localtime(time) -- will take the return value of time() and convert it
        into a nine element list:
    #  0    1    2     3     4    5     6     7     8
      seconds,minutes,hours,dayInMonth,Month (starting at 0), year, day in
      week, day in year, is it Daylight savings?
    ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) =
                                                localtime(time);
      In scalar context will return a string like:
	Tue Feb  9 10:27:55 1999					

      So: the code 

      $x= localtime(time);
      print $x. "\n".join(':',localtime(time))."\n";

      Produces:
      Tue Feb  9 10:28:48 1999
      48:28:10:9:1:99:2:39:0

      gmtime() will do same, but for Greenwich Mean Time.

3.  $0 == name of your perl script:
    $#ARGV==1 || die "Usage: $0 arg1 arg2\n";

4.  hex/decimal conversion:
    If you have a string $str containing a hex number (pattern matches
    /^x?[0-9a-f]*$/i) then hex($str) will return the decimal value of the
    contents of $str.  Sim'ly oct($str) will return the decimal value of the
    contents of $str, assuming it is a well-formed octal number (/^[0-7]*$/).