perl: Lookahead REs

Convert:
...
1|30|1|201002|745.11267931439|84.34214120933
1|30|1|201003|864.95194019049|322.6665129525
1|30|1|201006|831.27144204046|56.168021427546
...

into (truncate fractionals after 3 digits):

1|30|1|201002|745.112|84.342
1|30|1|201003|864.951|322.666
1|30|1|201006|831.271|56.168

use:

cat myfile | perl -pe 's/(?<=\.[0-9]{3})[0-9]*//g;'

note:

-p implies

while (<>) {
...
} continue {
print or die "-p destination: $!\n";
}