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Let's say that I have an arbitrary string like
`A man + a plan * a canal : Panama!` and I want to do a regex search for strings that are the same other than case. That is, this regular expression should match the string
`a man + A PLAN * a canal : PaNaMa!` I take it the best approach is to backslash-escape every character with a special meaning in Ruby regular expressions, and then do Regexp.new with that string and Regexp::IGNORECASE as arguments. Is that right? Is there a tried-and-true regular expression for converting arbitrary strings into literal regular expressions?
By the way, I ultimately want to use this regular expression to do an arbitrary case-insensitive MongoDB query. So if there's another way I could be doing that, please let me know.
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To enable the regex case insensitive matching, add (?) prefix or enable the case insensitive flag directly in the Pattern. compile() .
=~ is Ruby's pattern-matching operator. It matches a regular expression on the left to a string on the right. If a match is found, the index of first match in string is returned. If the string cannot be found, nil will be returned.
A regular expression is a sequence of characters that define a search pattern, mainly for use in pattern matching with strings. Ruby regular expressions i.e. Ruby regex for short, helps us to find particular patterns inside a string. Two uses of ruby regex are Validation and Parsing.
The regular expression pattern is matched in the input string from left to right. Comparisons are case-sensitive. The ^ and $ language elements match the beginning and end of the input string. The end of the input string can be a trailing newline \n character.
You can use Regexp.escape to escape all the characters in the string that would otherwise be handled specially by the regexp engine.
Regexp.new(Regexp.escape("A man + a plan * a canal : Panama!"), Regexp::IGNORECASE) or
Regexp.new(Regexp.escape("A man + a plan * a canal : Panama!"), "i") Ruby regexes can interpolate expressions in the same way that strings do, using the #{} notation. However, you do have to escape any regex special characters. For example:
input_str = "A man + a plan * a canal : Panama!" /#{Regexp.escape input_str}/i If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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