That means, before you consume each character, you perform a negative lookahead to confirm that the character isn't the beginning of a matching sequence: (?!.).Īnd you have to examine every character, so the regex has to be anchored at both ends: /^(?:(?!.).)*$/ Copied We passed the following 2 parameters to the String. The replace () method will return a new string where any vowel in the original string is replaced with an empty string. The inverse of that statement is, at EVERY point the condition is FALSE. To determine whether the first letter in a string is a vowel or a consonant, you can do without a regular expression. To remove the vowels from a string, call the replace () method with the following regular expression - / aeiou/gi, e.g. In other words, at ANY point, the condition is TRUE. Taking the more common, Perl semantics, /./ means the target string contains a sequence consisting of an 'a' or 'b' followed by at least one (non-line separator) character. For example, the character class aeiou matches any lower case vowel, while aeiou matches. That's because the regex passed to the matches() method is implicitly anchored at both ends (i.e., /^.$/). Regular expression syntax Syntax and semantics of the.
For example, in Perl, this is true: "abc" =~ /./īut in Java, this isn't: "abc".matches(".") You also need to take into account the semantics of the regex tool you're using. But I think that was just a typo in the blog entry.
Maybe it's different in vim, but in every regex flavor I'm familiar with, the caret matches the beginning of the string (or the beginning of a line in multiline mode). It will match qrcbk as well contrary to you example. which matches: aeyiuo aeYYuo qrcbk aeeeee. Only consonants (or any other non-vowel char) would be: b bsaeiyou+b. Python regular expression for consonants and vowels I was trying to create a regular expression which would allow any number of consonants, or any number of vowels, or a mix of consonants and vowels such that we only have any number of consonants in the beginning followed by any number of vowels ONLY, no consonant should be allowed after the. The reason your inverted regex isn't working is because of the ' ^' inside the negative lookahead: /^((?!^.).)*$/ If you want only vowels aeiyou try: b aeiyou+b. It will find words that start with one of the plosives ('p','b','t','d') followed by a character that is not a vowel ('a','e','i','o','u').