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Fix #86 - Replace character set with character group

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Zeeshan Ahmed 2017-08-24 10:14:08 +05:00
parent c38baf18f4
commit 17571a9d82
1 changed files with 7 additions and 7 deletions
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@ -405,13 +405,13 @@ that is matched by the first part of the expression. To define a positive
lookahead, parentheses are used. Within those parentheses, a question mark with
equal sign is used like this: `(?=...)`. Lookahead expression is written after
the equal sign inside parentheses. For example, the regular expression
`[T|t]he(?=\sfat)` means: optionally match lowercase letter `t` or uppercase
`(T|t)he(?=\sfat)` means: optionally match lowercase letter `t` or uppercase
letter `T`, followed by letter `h`, followed by letter `e`. In parentheses we
define positive lookahead which tells regular expression engine to match `The`
or `the` which are followed by the word `fat`.
<pre>
"[T|t]he(?=\sfat)" => <a href="#learn-regex"><strong>The</strong></a> fat cat sat on the mat.
"(T|t)he(?=\sfat)" => <a href="#learn-regex"><strong>The</strong></a> fat cat sat on the mat.
</pre>
[Test the regular expression](https://regex101.com/r/IDDARt/1)
@ -422,12 +422,12 @@ Negative lookahead is used when we need to get all matches from input string
that are not followed by a pattern. Negative lookahead defined same as we define
positive lookahead but the only difference is instead of equal `=` character we
use negation `!` character i.e. `(?!...)`. Let's take a look at the following
regular expression `[T|t]he(?!\sfat)` which means: get all `The` or `the` words
regular expression `(T|t)he(?!\sfat)` which means: get all `The` or `the` words
from input string that are not followed by the word `fat` precedes by a space
character.
<pre>
"[T|t]he(?!\sfat)" => The fat cat sat on <a href="#learn-regex"><strong>the</strong></a> mat.
"(T|t)he(?!\sfat)" => The fat cat sat on <a href="#learn-regex"><strong>the</strong></a> mat.
</pre>
[Test the regular expression](https://regex101.com/r/V32Npg/1)
@ -436,11 +436,11 @@ character.
Positive lookbehind is used to get all the matches that are preceded by a
specific pattern. Positive lookbehind is denoted by `(?<=...)`. For example, the
regular expression `(?<=[T|t]he\s)(fat|mat)` means: get all `fat` or `mat` words
regular expression `(?<=(T|t)he\s)(fat|mat)` means: get all `fat` or `mat` words
from input string that are after the word `The` or `the`.
<pre>
"(?<=[T|t]he\s)(fat|mat)" => The <a href="#learn-regex"><strong>fat</strong></a> cat sat on the <a href="#learn-regex"><strong>mat</strong></a>.
"(?<=(T|t)he\s)(fat|mat)" => The <a href="#learn-regex"><strong>fat</strong></a> cat sat on the <a href="#learn-regex"><strong>mat</strong></a>.
</pre>
[Test the regular expression](https://regex101.com/r/avH165/1)
@ -453,7 +453,7 @@ regular expression `(?<!(T|t)he\s)(cat)` means: get all `cat` words from input
string that are not after the word `The` or `the`.
<pre>
"(?&lt;![T|t]he\s)(cat)" => The cat sat on <a href="#learn-regex"><strong>cat</strong></a>.
"(?&lt;!(T|t)he\s)(cat)" => The cat sat on <a href="#learn-regex"><strong>cat</strong></a>.
</pre>
[Test the regular expression](https://regex101.com/r/8Efx5G/1)