正则表达式单词匹配

Question

I am trying to match a word in a string using \\b

For example

I want to match the word abcde in the string xyz abcde ddd and xyz abcde.html ddd . I am using a regular expression \\babcde\\b and what I want is to match only the first string but not the second since it contain abcde.html . But this regex matches both of them.

How can I achieve the result I want?

Answer 1

You can use a negative look-ahead to avoid matching any abcde followed by a period and alphanumerics:

\babcde\b(?!\.\w+)

See demo

The (?!\\.\\w+) negative look-ahead makes checks, but does not cosume the presence of the period and alphanumerics, and if they are present, no match is returned. You can make it more generic by replacing \\w+ with \\S+ (1 or more non-whitespace characters).

Answer 2

You can also use a positive look-ahead

\babcde\b(?=\s)

Demo here

The (?=\\s) check any white space character [\\r\\n\\t\\f ] after babcde

Answer 3

\\babcde(?=.*?\\b) a look ahead is what you need. I'll do up an example with a test link in a moment.

update: http://refiddle.com/2ing

edit: if by "second string" you mean the ".html" part then this answer will work. but if you meant the whole second string of "xyz abcde.html ddd" then stribizhev has the right answer.