4
, . , . " " - , regex regexp. , , , .
, , - , . , , , . , , :
:
- john_doe;
- jo-hn_doe;
- john12_as.
, , Jo, .
, , . , "The" "t", "h", "e".
- "the" => The fat cat sat onthemat.
, , . , . :
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. |
, . |
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[ ] |
, . |
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[^ ] |
Negated character class. Matches any character that is not contained between the square brackets |
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* |
0 . |
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+ |
1 . |
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? |
. |
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{n,m} |
"n", "m" . |
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(xyz) |
. |
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. |
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\ |
. [ ] ( ) { } . * + ? ^ $ \ | |
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^ |
. |
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$ |
. |
, . :
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. |
, |
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\w |
- :[a-zA-Z0-9_] |
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\W |
- :[^\w] |
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\d |
: [0-9] |
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\D |
: [^\d] |
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\s |
: [\t\n\f\r\p{Z}] |
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\S |
: [^\s] |
Look Around
Look Around , , . , , , .
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?= |
Lookahead |
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?! |
Lookahead |
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?<= |
Lookbehind |
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? |
Lookbehind |
, . .
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i |
: . |
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g |
: . |
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m |
: . |
vs.
"" , .
- "/(.*at)/" => The fat cat sat on the mat.
"" , ?. .
- "/(.*?at)/" => The fat cat sat on the mat.
