Lookbehind assertions


show more Lookbehind assertions provides you with in-depth training on Developer. Taught by Kevin Skoglund as part of the Using Regular Expressions show less
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Lookbehind assertions

In this movie, we're going to be learning about lookbehind assertions, and the metacharacters that we'll use for those are question mark, less than sign, equals for a positive lookbehind assertion, and question mark, less than, exclamation point for a negative lookbehind assertion. A lookbehind assertion is an assertion of what ought to be behind. It's very similar to what we had with lookahead assertions. If the lookbehind expression fails, then the match will fail. Any valid regular expression can be used inside there, and just like the lookahead assertions, they are going to be zero-width; they don't include the group in the match.

It's just an assertion about what ought to be true. The syntax is also very similar. You have, inside a group's expression, the very first characters will be question mark, less than, and the equal sign, followed by your regular expression. Or, question mark, less than, exclamation point, followed by your regular expression. Don'...

Lookbehind assertions
Video duration: 6m 26s 5h 36m Intermediate

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Lookbehind assertions provides you with in-depth training on Developer. Taught by Kevin Skoglund as part of the Using Regular Expressions

Subject:
Developer
Software:
Regular Expressions
Author:
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