What is metacharacters in regex?
A metacharacter is a character that has a special meaning during pattern processing. You use metacharacters in regular expressions to define the search criteria and any text manipulations….Search string metacharacters.
| Metacharacter | Action |
|---|---|
| ( ) | Group the regular expression within the parentheses. |
What are Perl special characters?
The Special Character Classes in Perl are as follows: Digit \d[0-9]: The \d is used to match any digit character and its equivalent to [0-9]….Perl | Special Character Classes in Regular Expressions.
| Class | Description |
|---|---|
| alpha | Any alphabetical character (“[A-Za-z]”) |
| alnum | Any alphanumeric character (“[A-Za-z0-9]”). |
| ascii | Any character in the ASCII character set. |
How do you pass special characters in Perl?
Perl String Escape Sequences
- Displaying email address in Perl. The character @ has a special meaning in perl.
- Escaping the $ sign in double quote strings.
- How to escape the escape character backslash (\)
- Double q operator – qq.
- Single q operator – q.
How do I print special characters in Perl?
my $var = “\\n”; $var =~s/\\//g; print “$'”; Else If you want print the \n . Just use the single quotes instead of double quotes. or use forward slashes within double quotes.
What is $1 Perl?
$1 equals the text ” brown “.
How do I match a character in Perl?
m operator in Perl is used to match a pattern within the given text. The string passed to m operator can be enclosed within any character which will be used as a delimiter to regular expressions.
What are the different meta characters?
Meta characters in regular expressions
| Meta character | Description |
|---|---|
| [ xyz ] | A character set. Matches any one of the enclosed characters. For example, [abc] matches the a in plain. |
| [^ xyz ] | A negative character set. Matches any character that is not enclosed. For example, [^abc] matches the p in plain. |
What is Quotemeta in Perl?
quotemeta EXPR quotemeta. Returns the value of EXPR with all the ASCII non-“word” characters backslashed. (That is, all ASCII characters not matching /[A-Za-z_0-9]/ will be preceded by a backslash in the returned string, regardless of any locale settings.)
What special character would you use to specify any non digit?
Non-digit: any character except \d , for instance a letter. \S. Non-space: any character except \s , for instance a letter. \W.
What is QX in Perl?
PERL QX FUNCTION. Description. This function is a alternative to using back-quotes to execute system commands. For example, qx ls − l will execute the UNIX ls command using the -l command-line option. You can actually use any set of delimiters, not just the parentheses.
Where can I find the documentation about Perl regular expressions?
The top level documentation about Perl regular expressions is found in perlre. This manual page discusses the syntax and use of character classes in Perl regular expressions. A character class is a way of denoting a set of characters in such a way that one character of the set is matched.
What are the most common character classes used in Perl?
Certainly, most Perl documentation does that. The dot (or period), . is probably the most used, and certainly the most well-known character class. By default, a dot matches any character, except for the newline.
Which characters are legal quantifiers in Perl?
For example, none of \\N {COLON}, \\N {4F}, and \\N {F4} contain legal quantifiers, so Perl will try to find characters whose names are respectively COLON, 4F, and F4. \\d matches a single character considered to be a decimal digit.