Counting time between lines

I want to count the time (in seconds) between two lines, which appear in my output window, and then store it in a variable. The counter should start at the first line, then stop and store the elapsed time at the second line. How do I do this?

Make two triggers?

http://www.gammon.com.au/scripts/doc.php?lua=utils.timer

This is what I did, but it still doesn't work:

<triggers>
<trigger
enabled="y"
expand_variables="y"
match="^([[:alpha:]]+) brings back (her|his) arm\, locking eyes with you"
regexp="y"
send_to="12"
sequence="100"
>
<send>check_fury = utils.timer ()</send>
</trigger>
</triggers>

<triggers>
<trigger
enabled="y"
match="^([[:alpha:]]+) hurls ([[:alpha:]]+) at you\, which returns to (her|his) hand\. You"
regexp="y"
send_to="12"
sequence="100"
>
<send>time_fury = utils.timer () - check_fury</send>
</trigger>
</triggers>

The variables don't get the new values. Can you help me?

Do your triggers fire at all? That's the first step, but we can't tell from what you wrote.

I tested my triggers and they do fire.

Good. Now try using SetVariable/GetVariable instead of local variables.

How do you know? How did you display the variables?

To Nick Gammon: I tested the triggers a few times with different time interval between them. After each test, I glanced at World Properties... > Scripting > Variables to see the value of my variables, but they always stood with the default value.

I updated my triggers and now I use SetVariable/GetVariable as Fiendish suggested. I did a test with my triggers as follows:

<triggers>
<trigger
enabled="y"
match="^([[:alpha:]]+) brings back (her|his) arm\, locking eyes with you"
regexp="y"
send_to="12"
sequence="100"
>
<send>SetVariable ("check_fury", "utils.timer ()")
DoAfter (math.floor (GetVariable ("time_fury") - 0.5), "duck")</send>
</trigger>
</triggers>

<triggers>
<trigger
enabled="y"
match="^([[:alpha:]]+) hurls ([[:alpha:]]+) at you\, which returns to (her|his) hand\. You"
regexp="y"
send_to="12"
sequence="100"
>
<send>SetVariable ("time_fury", "utils.timer () - check_fury")</send>
</trigger>
</triggers>

During this test my "check_fury" variable updated with "utils.timer ()" value and my "time_fury" variable remained unchanged. Then, I removed the quotes:

<triggers>
<trigger
enabled="y"
match="^([[:alpha:]]+) brings back (her|his) arm\, locking eyes with you"
regexp="y"
send_to="12"
sequence="100"
>
<send>SetVariable ("check_fury", utils.timer ())
DoAfter (math.floor (GetVariable ("time_fury") - 0.5), "duck")</send>
</trigger>
</triggers>

<triggers>
<trigger
enabled="y"
match="^([[:alpha:]]+) hurls ([[:alpha:]]+) at you\, which returns to (her|his) hand\. You"
regexp="y"
send_to="12"
sequence="100"
>
<send>SetVariable ("time_fury", utils.timer () - check_fury)</send>
</trigger>
</triggers>

This time my "check_fury" variable updated with "128839.22926007" value and my "time_fury" variable remained unchanged again.

It looks like you're complicating things a bit. Going back to what you originally posted, try this modification...

You don't have to use get and set variable, but you do need to understand about the different types of variables.

http://www.gammon.com.au/forum/?id=10863