"John W. Kennedy" <[EMAIL PROTECTED]>
07/29/2005 04:13 PM
To
[EMAIL PROTECTED]
cc
[email protected]
Subject
Re: randomly choosing a file
[EMAIL PROTECTED] wrote:
> I know how to and can successfully open a directory , but i need to
choose
> a file within the directory at random to verify the data on. does anyone
> have any suggestions of how to do this? i'm thinking it could take a
while
> to create an array of the file names and then randomly pick a slot
there,
> but that;s all i can think of right now.
Unfortunately, this is not likely to do you any good, because you need
to know the value of n before starting, and the correct value can be
obtained only by reading the directory in the first place. So....
my @entries;
opendir MYDIR, $directory;
while (my $entry = readdir MYDIR) {
next if -d "$directory/$entry";
push @entries, $entry;
}
closedir MYDIR;
my $chosenfile = @entries[int rand ($#entries + 1)];
this looks like a more efficient variation upon what i was thinking. i
have one question though.. the array starts at 0 for an index, doesn't
$#var give one less than the element in the array since it uses the last
index in the array? wouldn't this mean one wants to *1 to make an integer
instead of +1 and make the result 1 to [one-greater-than-array] ?
i figure since there seems to be many people interested in this, that
potential issue should be brought up here so everyone corrects it if there
is a mistake. since it is close to what i was thinking it's the type of
code i would write so I'm going to assimilate some things from that to
improve my efficiency =o)
i cant use the other suggestion because the script its to test a new
version of RAIDCORE being used and needs to be alternating to some degree
between read and writes, the reads are supposed to use a verification
script we already have. we're playing with mirroring/transforming R5
arrays.
thnx for the help!
thnx in advance for answering the + versus * question.
-Josh
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