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Diffstat (limited to 'doc/flex.texi')
| -rw-r--r-- | doc/flex.texi | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/doc/flex.texi b/doc/flex.texi index 04aff51..54be073 100644 --- a/doc/flex.texi +++ b/doc/flex.texi @@ -997,6 +997,13 @@ just the single character @samp{a}). The @samp{@{-@}} operator is left associative, so @samp{[abc]@{-@}[b]@{-@}[c]} is the same as @samp{[a]}. Be careful not to accidently create an empty set, which will never match. +@item + +The @samp{@{+@}} operator computes the union of two character classes. For +example, @samp{[a-z]@{+@}[0-9]} is the same as @samp{[a-z0-9]}. This operator +is useful when preceded by the result of a difference operation, as in, +@samp{[[:alpha:]]@{-@}[[:lower:]]@{+@}[q]}, which is equivalent to +@samp{[A-Zq]} in the "C" locale. @cindex trailing context, limits of @cindex ^ as non-special character in patterns |