Beefy Boxes and Bandwidth Generously Provided by pair Networks
laziness, impatience, and hubris
 
PerlMonks  

Re: two + 2 not equal 4!

by toolic (Bishop)
on Jul 24, 2010 at 02:09 UTC ( #851103=note: print w/replies, xml ) Need Help??


in reply to two + 2 not equal 4!

Tip #6 from the Basic debugging checklist: use B::Deparse to see if your code really is what you think it is:
$ perl -MO=Deparse two.pl BEGIN { $^W = 1; } sub two { use strict 'refs'; 2; } use strict 'refs'; printf "two + 2 = %d\n", two(2);

So, two + 2 is interpreted as two(2). Instead of evaluating your function, then adding 2, perl treats everything after your function call as a LIST of arguments when you omit the parentheses. From perlsub:

2. NAME LIST; # Parentheses optional if predeclared/imported.

While it is legal syntax to omit the parentheses on function calls, it is a good practice to use them, even if your function does not need arguments:

printf "two + 2 = %d\n",two() + 2;

As a side note, your code would render better if you replace your "pre" tags with "code" tags: Writeup Formatting Tips

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://851103]
help
Chatterbox?
[abner]: yes. i am familiar with mysql but ignorant about how to get around the fact that placeholders can only represent single scalar values.
[abner]: my $sth = $dbh->prepare(' SELECT * FROM charge WHERE cpt = ?') or die "Couldn't prepare statement: " . $dbh->errstr;
[abner]: what if i want SELECT * FROM charge WHERE col1 = x and col2 = y?
[atcroft]: abner: So you are wanting to do something like my $sth = $dbh->prepare(' SELECT * FROM charge WHERE col1 = ? and col2 = ?;'); $sth->execute(' asdf', 'asdw');?
[atcroft]: (Full disclosure: I may have the idea right but small typographical errors, so please test any code I suggest. :) )

How do I use this? | Other CB clients
Other Users?
Others browsing the Monastery: (5)
As of 2017-01-24 03:52 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    Do you watch meteor showers?




    Results (201 votes). Check out past polls.