The basis of regular expressions (II.)

5.6 Locator

^, which can be used to represent the beginning of a row.

$, which can be used to represent the end of a line.

\b, the bounds of the character, such as er\b, will match the ER in "never OK" and not the ER in "verb".

\b, in contrast to the role of \b.

Examples of application of locators:

A. If you want to perform a replacement task in a large paragraph of text, be careful, such as replacing win as lose, the win a window will be replaced with lose a losedow, which is not the desired result, the correct way should be to use \bwin\b for lose.

B. The correct expression for verifying the email address is: ^[a-za-z_-][email protected][a-za-z_-]+ (\.[ a-za-z_-]+) +$.

C. Add an identity to the beginning of each line of text, simply replace the ^ with an identity.

The basis of regular expressions (II.)