How to write this cron expression?

Question

How to write cron expression (for quartz.net, but that shouldn't matter) that would trigger:

every week day from 8am to 7pm once in half an hour

Answer 1

Tested:

0 0/30 8-18 ? * 1-5

NOTE: Last trigger will fire at 18:30, not 19:00. If you change to:

0 0/30 8-19 ? * 1-5

Last trigger will be 19:30. I don't believe there is a way to have last trigger fire at exactly 19:00, with half-hourly intervals.