That is it for JavaScript regex match example. If there are no matches found using match() method, no matter if there’s flag g or not, the null is returned. To find more than one match you need to add a g. If the regex has flag g, then it returns the array of all matches as strings. Given a regex it will return the match or matches found in the string. If the regex doesn’t have flag g, then it returns the first match as an array. Here “ i” flag helps to find the case-sensitive match in the given string. If you pass the “ i” flag in the regex, then it will return true. Our pattern is well, and our input string contains Well. So, there is a mismatch between the input string and pattern. If you want to check a case-sensitive match, then you have to pass “ i” flag explicitly. By default, the string match() method does not check case sensitive match. If you don’t pass the case sensitivity flag “ i” explicitly, then it will return null. Here “ g” flag suggests that the regular expression should be tested against all possible matches in the string. You can play with the regex and sample text in this live regex demo.In this example, we are searching globally for a Well pattern, and it finds two times in the string. # Other examples of groups we could match # The match method returns an array of the regex matches or null if there are no matches found. ) # End DEFINE # The Regex Matching Starts Here # To count the number of regex matches, call the match() method on the string, passing it the regular expression as a parameter, e.g. ) # end one_to_999_999_999_999_999 definition Matching numbers that divide by other numbers: \d0 matches any number that divides by 10 - any number ending in 0 \d00 matches any number that divides by 100 - any number ending in 00 \d 05 matches any number that divides by 5 - any number ending in 0 or 5 \d 02468 matches any number that divides by 2 - any number ending in 0,2,4,6 or 8. I've also ignored the 7e5 notation for numbers, that would need a bit of extra work to avoid matching the e in true. my crude parser won't cope at all well if it isn't. (?&two_digit_prefix)(?:(?&one_to_9))?|(?&ten_to_19)| Handling the numbers in strings is too tricky using a RegExp so I haven't even tried. # twenty|thirty|forty|fifty|sixty|seventy|eighty|ninety # ten|eleven|twelve|thirteen|fourteen|fifteen|sixteen|seventeen| # one|two|three|four|five|six|seven|eight|nine # They build on each other like lego until we can define # Within this DEFINE block, we'll define many subroutines There are plenty of comments in the regex, so if you read the defined subroutine page, you shouldn't need further explanations. There you can decide to match a big number by calling the big_number subroutine with (?&bignumber), or to match smaller numbers using subroutines such as (?&one_to_99), and so on. We define some named subroutines- one_to_9, ten_to_19-then more named subroutines that build on the earlier ones: one_to_99, one_to_999…Īt the bottom, after defining all the groups, is where the real matching begins. The regex built in a modular way-like lego. As such, it only works in engine that support that syntax-currently Perl, PCRE (PHP, Delphi, R…) and Python's alternate regex engine. This pattern was an excuse to build a beautiful regex using the defined subroutine syntax (?(DEFINE) … ). Nine hundred ninety nine thousand two hundred thirteen
This page presents a regular expression to match numbers in plain English, such as:
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