| 1 |
The variables \1, \2, \3 etc. correspond to parentheses inside the regex. Outside the regular expression use the PERL variables $1, $2, $3 etc.
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| 2 |
In string matching, we identify three parts:
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$` is variable holding substring BEFORE matched part
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$& is variable holding substring matched by regular expression
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$' is variable holding substring AFTER matched part
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| 3 |
So original string is the concatenation $` . $& . $'
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| 4 |
Note, however, any script that uses these variables suffers a significant performance hit!
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