Regex: How to not match the last character of a word?

Question

I am trying to create a regex that does not match a word (a-z only) if the word has a : on the end but otherwise matches it. However, this word is in the middle of a larger regex and so I (don't think) you can use a negative lookbehind and the $ metacharacter.

I tried this negative lookahead instead:

([a-z]+)(?!:)

but this test case

example:

just matches to

exampl

instead of failing.

Answer 1

If you are using a negative lookahead, you could put it at the beginning:

(?![a-z]*:)[a-z]+

i.e: "match at least one a-z char, except if the following chars are 0 to n 'a-z' followed by a ':'"

That would support a larger regex:

 X(?![a-z]*:)[a-z]+Y

would match in the following string:

 Xeee Xrrr:Y XzzzY XfffZ

only 'XyyyY'

Answer 2

Try this:

[a-z]\s

Answer 3

([a-z]+\b)(?!:)

asserts a word boundary at the end of the match and thus will fail "exampl"

Answer 4

[a-z]+(?![:a-z])