Beefy Boxes and Bandwidth Generously Provided by pair Networks
more useful options
 
PerlMonks  

Re: Check even numbers?

by cees (Curate)
on Aug 07, 2006 at 05:02 UTC ( #565891=note: print w/replies, xml ) Need Help??


in reply to Check even numbers?

If you want to count the number of occurences of a single character in a string, then you should look at using 'tr'.

$str = 'ABABAABBA'; $count = $str =~ tr/A//; # $a = 5;

If you omit the second arg to tr, it knows you are not changing the string, but still counts up the occurences for you, which makes this very efficient.

After that you just have to see if the number is positive ($count > 0) and use Grandfather's test above to see if it is even ( !($count & 1) ).

if ($count && !($count & 1)) { # Do something with this protein sequence }

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://565891]
help
Chatterbox?
[ambrus]: Is this for work?
[Eily]: Discipulus try looking at $@
[Eily]: or count the parentheses :)
[Discipulus]: stupid me! I had to stay at home and do not code with the flu..
[holli]: bacause it's a syntax error
[Discipulus]: yes sorry forget and forgive me
[Eily]: for what it's worth I didn't go for the brightest solution either
[Eily]: I tried print eval '2+1/3*(2+2/5))' or print $@

How do I use this? | Other CB clients
Other Users?
Others surveying the Monastery: (5)
As of 2017-10-24 10:19 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    My fridge is mostly full of:

















    Results (287 votes). Check out past polls.

    Notices?