¿Cómo puedo comparar múltiples expresiones regulares en Perl?

How can I match against multiple regexes in Perl?

In this example, perl must recompile the regular expression for every iteration of the C loop since it has no way to know what C will be: The C operator showed up in perl 5.005. It compiles a regular expression, but doesn’t apply it. When you use the pre-compiled version of the regex, perl does less work.

Regular Expression Variables Regular expression variables include $, which contains whatever the last grouping match matched; $&, which contains the entire matched string; $`, which contains everything before the matched string; and $’, which contains everything after the matched string. Following code demonstrates the result −

The match operator, m//, is used to match a string or statement to a regular expression. The m// actually works in the same fashion as the q// operator series.you can use any combination of naturally matching characters to act as delimiters for the expression. For example, m{}, m(), and m>< are all valid.

For cases like these, Perl allows the use of WildCards in the Regular Expression. Perl allows to search for a specific set of words or the words that follow a specific pattern in the given file with the use of Wild cards in Regular Expression. Wild cards are ‘dots’ placed within the regex along with the required word to be searched.

It compiles a regular expression, but doesn’t apply it. When you use the pre-compiled version of the regex, perl does less work. In this example, I inserted a C to turn each pattern into its pre-compiled form. The rest of the script is the same, but faster: In some cases, you may be able to make several patterns into a single regular expression.

The Perl code is within quotes. Although it’s possible to string several -e statements in a row, we won’t do it here. ✽ The -n flag feeds the input to Perl line by line. ✽ -0777 changes the line separator to undef, letting us to slurp the file, feeding all the lines to Perl in one go.

✽ The -p flag (printing loop) processes the file line by line and prints the output. ✽ To replace directly in the file you can use the -i flag… but first test your one-liner without the -i to make sure it’s what you want.