usenet@carssdf.UUCP (John Watson) (03/20/90)
OK, so I'm a little dense, can one of you perl
'hackers' tell me the difference between
split('_'); and split(/_/); When used on files
delimited by '_' like this:
First_Last_Address_City_State_Zip_etc...\n
Does it make any difference? Is one faster?
When would it make a difference?
John Watson rutgers!carssdf!usenetlwall@jpl-devvax.JPL.NASA.GOV (Larry Wall) (03/21/90)
In article <237@carssdf.UUCP> usenet@carssdf.UUCP (John Watson) writes:
: OK, so I'm a little dense, can one of you perl
: 'hackers' tell me the difference between
: split('_'); and split(/_/); When used on files
: delimited by '_' like this:
: First_Last_Address_City_State_Zip_etc...\n
: Does it make any difference? Is one faster?
: When would it make a difference?
Semantically, there's no difference. The /_/ form is preferred because
it will run faster. Saying '_' works because it's an expression, so
it is evaluated at runtime. Perl does recognize the specific case of
a single quoted string as something which won't change, so it doesn't
recompile the regular expression each time. But it does miss out on
the optimization that happens on /_/ (which will bypass the regular
expression routines entirely, enabling a substantial speedup).
The one runtime pattern ' ' is a special case. It actually gets translated
to /\s+/, with the additional feature of skipping leading whitespace like
awk does.
Larry