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Notice the string I typed in
the last video, wwwgoogle.com.

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00:00:06,410 --> 00:00:09,440
Even though we've grouped
the www dot together,

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00:00:09,440 --> 00:00:14,390
the regex is still finding a partial
match in this test string.

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00:00:14,390 --> 00:00:19,920
As you can see, it does this by starting
to match the pattern later in the string,

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at the fourth character.

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00:00:21,850 --> 00:00:26,501
We can see the opposite problem by
typing another test string with extra

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characters at the end.

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00:00:30,434 --> 00:00:34,870
Google.com with a couple extra m's.

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00:00:34,870 --> 00:00:39,840
If we're trying to match google.com,
neither of these strings are valid.

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00:00:39,840 --> 00:00:44,720
We can tell the parser to only consider
these a match if the entire string

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00:00:44,720 --> 00:00:49,330
fits our pattern and
to reject partial matches like these.

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00:00:50,430 --> 00:00:54,250
You'll see these characters
often in regular expressions.

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They are very useful in ensuring that
you're only matching at the beginning or

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ending of a string.

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00:01:00,980 --> 00:01:06,474
While other reg ex characters have
represented characters in strings,

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these only represent location.

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00:01:09,003 --> 00:01:13,630
As I mentioned in the first video,
make sure you have the m flags set.

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00:01:13,630 --> 00:01:19,060
This lets us treat each line as
a separate string, rather than one block.

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To tell the parser to only start matching
at the beginning of a test string,

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I'll put a caret at
the beginning of the regex.

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You see that excluded wwwgoogle.com,

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00:01:32,813 --> 00:01:37,830
because if www is present,
it must be followed by a dot.

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00:01:38,840 --> 00:01:43,617
Now, to specify that the string
must end with .net or

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.com with only one m, I put a dollar
sign at the end of the expression.

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00:01:49,976 --> 00:01:53,270
Now all the valid strings are matched.

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00:01:53,270 --> 00:01:58,100
You'll probably use the caret and dollar
sign often in your regular expressions

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00:01:58,100 --> 00:02:02,050
to eliminate strings that contain
the pattern you're matching.

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00:02:02,050 --> 00:02:05,750
But as a whole would
be considered invalid.

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00:02:05,750 --> 00:02:07,610
For some additional practice,

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once again check the notes
associated with this video.