如何在perl中计算一行中的单词数？

Question

I know I could write my own while loop along with regex to count the words in a line. But, I am processing like 1000 lines and I dont want to run this loop each and every time. So, I was wondering is there any way to count the words in the line in perl.

Answer 1

1000 times is not a significant number to a modern computer. In general, write the code that makes sense to you, and then, if there is a performance problem, worry about optimization.

To count words, first you need to decide what is a word. One approach is to match groups of consecutive word characters, but that counts "it's" as two words. Another is to match groups of consecutive non-whitespace, but that counts "phrase - phrase" as three words. Once you have a regex that matches a word, you can count words like this (using consecutive word characters for this example):

scalar( () = $line =~ /\w+/g )

Answer 2

How about splitting the line on one or more non-word characters and counting the size of the resulting array?

$ echo "one, two, three" | perl -nE "say scalar split /\W+/"
3

As a sub that would be:

# say count_words 'foo bar' => 2
sub count_words { scalar split /\W+/, shift }

To get rid of the leading space problem spotted by ysth, you can filter out the empty segments:

$ echo " one, two, three" | perl -nE 'say scalar grep {length $_} split /\W+/'
3

…or shave the input string:

$ echo " one, two, three" | perl -nE 's/^\W+//; say scalar split /\W+/'
3