word-boundary

问题 Does PostgreSQL support \\b ? I\'m trying \\bAB\\b but it doesn\'t match anything, whereas (\\W|^)AB(\\W|$) does. These 2 expressions are essentially the same, aren\'t they? 回答1: PostgreSQL uses \m , \M , \y and \Y as word boundaries: \m matches only at the beginning of a word \M matches only at the end of a word \y matches only at the beginning or end of a word \Y matches only at a point that is not the beginning or end of a word See Regular Expression Constraint Escapes in the manual. There

问题 I am having a problem with matching word boundaries with REGEXP_LIKE. The following query returns a single row, as expected. select 1 from dual where regexp_like(\'DOES TEST WORK HERE\',\'TEST\'); But I want to match on word boundaries as well. So, adding the \"\\b\" characters gives this query select 1 from dual where regexp_like(\'DOES TEST WORK HERE\',\'\\bTEST\\b\'); Running this returns zero rows. Any ideas? 回答1: I believe you want to try select 1 from dual where regexp_like ('does test

问题 What are non-word boundary in regex (\\B), compared to word-boundary? 回答1: A word boundary ( \b ) is a zero width match that can match: Between a word character ( \w ) and a non-word character ( \W ) or Between a word character and the start or end of the string. In Javascript the definition of \w is [A-Za-z0-9_] and \W is anything else. The negated version of \b , written \B , is a zero width match where the above does not hold. Therefore it can match: Between two word characters. Between

问题 I have the following php code in a utf-8 php file: var_dump(setlocale(LC_CTYPE, \'de_DE.utf8\', \'German_Germany.utf-8\', \'de_DE\', \'german\')); var_dump(mb_internal_encoding()); var_dump(mb_internal_encoding(\'utf-8\')); var_dump(mb_internal_encoding()); var_dump(mb_regex_encoding()); var_dump(mb_regex_encoding(\'utf-8\')); var_dump(mb_regex_encoding()); var_dump(preg_replace(\'/\\bweiß\\b/iu\', \'weiss\', \'weißbier\')); I would like the last regex to replace only full words and not parts

问题 Assuming you have the following text: Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam Lorem! nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua.

问题 In JavaScript: \"ab abc cab ab ab\".replace(/\\bab\\b/g, \"AB\"); correctly gives me: \"AB abc cab AB AB\" When I use utf-8 characters though: \"αβ αβγ γαβ αβ αβ\".replace(/\\bαβ\\b/g, \"AB\"); the word boundary operator doesn\'t seem to work: \"αβ αβγ γαβ αβ αβ\" Is there a solution to this? 回答1: The word boundary assertion does only match if a word character is not preceded or followed by another word character (so .\b. is equal to \W\w and \w\W ). And \w is defined as [A-Za-z0-9_] . So \w

问题 string = c(\"apple\", \"apples\", \"applez\") grep(\"apple\", string) This would give me the index for all three elements in string . But I want an exact match on the word \"apple\" (i.e I just want grep() to return index 1). 回答1: Use word boundary \b which matches a between a word and non-word character, string = c("apple", "apples", "applez") grep("\\bapple\\b", string) [1] 1 OR Use anchors. ^ Asserts that we are at the start. $ Asserts that we are at the end. grep("^apple$", string) [1] 1

问题 I have a regex expression that I\'m using to find all the words in a given block of content, case insensitive, that are contained in a glossary stored in a database. Here\'s my pattern: /($word)/i The problem is, if I use /(Foo)/i then words like Food get matched. There needs to be whitespace or a word boundary on both sides of the word. How can I modify my expression to match only the word Foo when it is a word at the beginning, middle, or end of a sentence? 回答1: Use word boundaries: /\b(