$d-- is short for $d = $d -1, that is "subtract one from $d".

Date::Simple provides a date object, and you can add and subtract number from that, so today() - 1 is yesterday.

Then it decreases the value by one while the day of week is 0 (Sunday) or 6 (Saturday).

In reply to Re^3: Yesterday Date by moritz
in thread Yesterday Date by Anonymous Monk

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