I am trying to find out what is this regular expression [[:space:][:digit:]]+ stands for.
I learn from Wikipedia that [:space:] means Whitespace characters and [:digit:] means Digits from 0 to 9.
So I think [[:space:][:digit:]]+ matches any Whitespace characters followed by a digit like ' 1' or ' 9'.
But, when I try this in r:
> txt <- c("arm","foot","lefroo", "laura ")
> i <- grep("[[:space:][:digit:]]+", txt)
> txt[i]
[1] "laura "
there is no digit in "laura ", but it sill matched.
this really confused me, any one can explain this?
