$ perl -e 'print scalar(split /,/,"1,2,3,4")'
4
$ perl -e 'print scalar(split /,/,",2,3,4")'
4
$ perl -e 'print scalar(split /,/,"1,,3,4")'
4
$ perl -e 'print scalar(split /,/,"1,2,,4")'
4
$ perl -e 'print scalar(split /,/,"1,2,3,")'
3
$ perl -e 'print scalar(split /,/,"1,2,,")'
2