Splunk rex remove special characters12/20/2023 In Python 3.2 and earlier, \uFFFF works when you add your regex as a literal (Unicode) string to your Python code. But Python’s re module only supports \uFFFF starting with Python 3.3. Python has supported this syntax as part of (Unicode) string literals ever since Unicode support was added to Python. The actual POSIX standard states that the behavior of an “ordinary” character preceded by a backslash is “undefined”.Ī similar issue exists in Python 3.2 and prior with the Unicode escape \uFFFF. Depending on the implementation, the POSIX library interprets this as a literal n or as an error. If your code reads the same regex from a file, then the regex engine sees \n. Then the compiler interprets \n and the regex engine sees an actual newline character. So when developing an application in C using the POSIX library, \n is only interpreted as a newline when you add the regex as a string literal to your source code. But the C programming language does support escapes like \n and \x0A in string literals. For example, POSIX regular expressions do not support any of these escapes. If the regex engine does not support the same escapes, this can cause an apparent difference in behavior when a regex is specified as a literal string in source code compared with a regex that is read from a file or received from user input. Then such escapes are translated by the compiler into their actual characters before the string is passed to the regex engine. Many programming languages support similar escapes for non-printable characters in their syntax for literal strings in source code. If your regular expression engine supports Unicode, you can use \uFFFF or \x and treats \0377 as an error. But JGsoft V2 treats \c as an XML shorthand. The JGsoft flavor originally treated \cA through \cZ as control characters. In XML Schema regular expressions and XPath, \c is a shorthand character class that matches any character allowed in an XML name. They treat anything other than a letter after \c as an error. Metacharacters indeed lose their meaning immediately after \c in applications that support \cA through \cZ for matching control characters. The asterisk is character 0x2A in the ASCII table, so the lower 5 bits are 0x0A while flipping bit 0x40 gives 0圆A. But \c* might match a line feed or the letter j. Either way through \c_ would match control characters 0x00 through 0x1F. Or the application may just flip bit 0x40. The application may take the last 5 bits that character index in the code page or its Unicode code point to form an ASCII control character. Some allow any character after \c while other allow ASCII characters. Using characters other than letters after \c is not recommended because the behavior is inconsistent between applications. Only Java requires the A to Z to be uppercase. Most flavors allow the second letter to be lowercase, with no difference in meaning. \cM matches a carriage return, just like \r, \x0D, and \u000D. These are equivalent to \x01 through \x1A (26 decimal). The second letter is an uppercase letter A through Z, to indicate Control+A through Control+Z. The letter after the backslash is always a lowercase c. Many regex flavors also support the tokens \cA through \cZ to insert ASCII control characters. JGsoft V2 matches any vertical whitespace with \v. The JGsoft flavor originally matched only the vertical tab with \v. Earlier versions treated it as a needlessly escaped literal v. Perl 5.10, PCRE 7.2, PHP 5.2.4, R, Delphi XE, and later versions treat it as a shorthand. That includes the vertical tab, form feed, and all line break characters. In other flavors, \v is a shorthand that matches any vertical whitespace character. In some flavors, \v matches the vertical tab (ASCII 0x0B). Remember that Windows text files use \r\n to terminate lines, while UNIX text files use \n. More exotic non-printables are \a (bell, 0x07), \e (escape, 0x1B), and \f (form feed, 0x0C). Use \t to match a tab character (ASCII 0x09), \r for carriage return (0x0D) and \n for line feed (0x0A). You can use special character sequences to put non-printable characters in your regular expression.
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