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### Re^2: Determing Week Ranges between given date range?

by mojotoad (Monsignor)
 on Oct 12, 2010 at 17:20 UTC ( #864909=note: print w/replies, xml ) Need Help??

If you want the first day of the week to be something besides Sunday, you can do this:
```  my \$dow1 = 1; # (0-7)
...
while (\$week_s <= \$e) {
(\$week_e = \$week_s->clone())->add(
days => (\$dow1 + (7 - \$week_s->dow()) % 7,
);
...
[download]```

Cheers,
Matt

Replies are listed 'Best First'.
Re^3: Determing Week Ranges between given date range?
by ikegami (Pope) on Oct 12, 2010 at 18:16 UTC

If you want the first day of the week to be something besides Sunday

He wants it to be Monday.

you can do this:

You have an off-by-one error.

```my \$first_dow = 1;  # 0=Sun, 1=Mon, ..., 7=Sun

...

# Day before first \$first_dow after \$week_s
->add( days => ((7 - \$week_s->dow()) + (\$first_dow + 6)) % 7 );
[download]```
Sort of...actually, I cribbed that code from something I had lying around -- that code was designed around the convention of 0=Mon, 1=Tue, etc. But I forgot, oops.

After fixing that assumption, this also works (closer to the form I originally used). 0=Sun, 1=Mon ... :

```     days => (\$first_dow + (6 - \$week_s->dow())) % 7
[download]```
Thanks for spotting it.

Cheers,
Matt

Yeah, that's functionally equivalent, but I wanted to keep the two halves of the equation separate (calculating the last day of the week and calculating the number of days until the last day of the week). In mine, (\$first_dow + 6) can be replaced with \$last_dow.

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