Programming :: Perl - Store And Access An Array In A Hash Of Hashes?
Jul 7, 2010
I am in need of some syntax help. I'm trying to figure out how to store and retrieve an array out of a hash of hashes. For this example, I'm trying to access the city list for a particular state for a particular country. I understand I could do a join and split on the hash key to combine Country and State, but trying to keep things separated.The code I have gets in all the information for the Countries, and states, and gets the list of cities together, no problem. I store all the city names in an array, then make an anonymous pointer to the array for the hash, like this - $MY_CITIES{$COUNTRY}{$STATE} = [@CITIES]I believe that syntax is correct, or is it? What I'd like to do is I need to cycle through every hash to find if a city exists or not. If it exists in 3 states, then it should print 3 times. Here is the code block to search -
Code:
for $COUNTRY (@LIST_OF_COUNTRIES) {
for $STATE ( keys %MY_CITIES{$COUNTRY){$STATE} ) {
I'm trying to figure out how to code for this specific type of instance - I want to use a hash and have the key be a reference to an array, and not use the key in the standard way of it being a scalar. Basically, I have a large output that I need to process line by line, and rather have access to it as an array than a big block in a scalar. For the big block hash as a scalar I would do -
How would I code it that I would have access to the key information as an array and not a scalar? I know it needs to be a pointer and we're going to have -> in there somewhere, but not sure how to approach it. Some of the documentaiton I've been reading about referencing I've found a little confusing so far, and trying to figure out how to use them in context of what I'm working on.
I was reading about Ruby code blocks, but it's all a bit hazy.My questions:1. Can you store executable code in the value part of a hash (err...associative array)2. If you did, how would you call the code?3. If you executed this stored code, would it be possible when doing soto pass in an object to the code that it could use?
I am trying to make a hash of objects in perl (long story.) I have a package containing the main hash and all the subroutines necessary to work with it. My "new" subroutine used to add an object to the hash goes like this:
i have a loop which produces new value everytime it runs. i want to store the results in an array. how can i do dat??
loop is like: a=0 declare v while ((....)) do v[$a]="$r" let a=a+1 done
while doing this it is not treating v as array but as variable and it is overriding the value and old value is lost..i am using bash shell version 3.00.15
I am working on an structure program and i have to represent a 2,4 tree in a class in Java using single int array and make the insert and delete functions .
I tried to look for this, but there are so little of perl on internet: Code: @array = [$title, $description, $pubDate, $link]; push(@feeds1, $array);
I am trying to create a 2 D array by PUSH, so the output would look like: ([ $title, $description, $pubDate, $link ], [ $title, $description, $pubDate, $link ], [ $title, $description, $pubDate, $link ], [ $title, $description, $pubDate, $link ]...etc )
I have an array called @logons. How can I step thru the array and split the fields? This is what I have so far, but doesnt work. I got the feeling I the split statement syntax is incorrect.
Code:
print @logons; foreach my $logons(@logons){ ($userid, $ip) = split(',',$logons);
[code]....
Update: Appears the data in @logons has a column header from the mysql query which I used to populate it with. So that code which I was testing does indeed work.
So I need everything between each name, but I am not guaranteed that each time I match a name that I will have the same amount of lines, so I do a range pattern search line this to get all lines, no matter if there is 5 or 10 or 15. I simply do a loop that goes through the whole array until I hit the match, and this is my search pattern.
This works perfectly... until I hit the end and it doesn't get its final pattern match because it's at the end and there is no next entry with a (Address) line. So as a 'hack', I ended up inserting a final scalar at the end of the array that just says (Address) so it knows it's at the end. Ideally though, I'd like to do an "or" statement that says search for Address || return true if I hit the end of the array. How would I match on "End Of Array" essentially?
it's been a while since I logged on here! I've been trying my hand at a little perl and have hit a brick wall.I'm using the Imagemagick module to manipulate some images. I can get the following to work without issue:
I'm reading "OReilly Learning Perl 5th Edition", and there are such words:Code:You can use an array element like $fred[2] in every place? where you could use any other scalavariable like $fred.At the bottom of the page, it explains the ? like this:Code:The most notable exception is that the control variable of a foreach loop, which you?ll see later in this chapter, must be a simple scalar.Since Perl has the save-and-restore mechanism for the control variable, why an array element can't be used as the control variable
I'm trying access binary records that were created in Borland Delphi and stored in a SQL Server database (as a BLOB). What the heck is the syntax for accessing a two-D array in C#? Here's an example:
Code:
const MAX_BOWLERS = 8; gMAX_FRAMES = 40; ... type
[code]...
I've successfully got a valid "GameRec" over to C#-land. I want to access array element "GameRec.Frames[iBowler, iFrame]".
How do I define a C# type "TFrames = Array[1..Max_Bowlers, 0..gMax_Frames] of TFrame;" so that I can do it?
I have never used multidimensional array for a long time so please consider this as a newbie question. I am editing a program that uses a 4 dimensional array and I think I'm losing track of the indexes.
day = 0 to 30 hour = 0 to 23 channel = 0 to 7 len = 0 to 63 unsigned char idx[day][channel][hour][len];
I have seen that the assignment to a string is snprintf(idx[day][hour][channel], 64, "%s/%s", dayofmonth, hourofday); Is this correct? Because when I access with a day argument, that day value goes into the hour part.
When I deal with an array in a function I con not access to the content of array in a for loop, but out of a for loop I can access to them! for example
[code]...
In a function when I send as parameter, in a for loop it prints the content of array and out of a for loop it prints the address of arr[i]
I've been reading / trying to learn some Perl lately. I've found the free book, "Learning Perl", quite good and easy to follow most of the times. However, today I was testing one of the scripts in the book and it would only run partly.
Code:
#!/usr/bin/perl use warnings; use strict; my %inventory;
[code]....
This row is supposed to give option, either to use an additional script as pipe (sort.plx),or STDOUT if the extra script is not found.It works with the other script present, however, with the sort.plx being absent it simply wont use STDOUT instead but whines to me:
Can't open perl script "sort.plx": No such file or directory
Has the author of the original script done some error writing it? Since I'm a beginner and found most of the stuff confusing in Perl either way (having previously only experience in Bash and some in PHP) - I can't really tell for sure , but from what I can read in documentation - it doesn't appear to be wrong.As it looks now, the only way for me to use STDOUT is only by removing:
open (SORT, "| perl sort.plx") or *SORT = *STDOUT; select *SORT;
rows. But then, I lose the piping in to that other script as an option.
I have a Perl script behind a firewall. I want to access this script from Python on Google App Engine. I have access to the server running the Perl script via the following methods: SSH VPN What are the ways I can do this with Python on GAE? Can I use something like wget, login through ssh and run the script using perl interpreter?
Currently it is a CGI script that I can access through a web browser if I'm inside the firewall. My only other option is to turn the process around, i.e. have perl send data outside the firewall to google app engine. But I want to know if this is possible as it is now without changing the perl script.
The below snippet works fine until I use strict. Then it dies with the following error: uote:Can't use string ("html") as an ARRAY ref while "strict refs" in use at ./filetest3 line 18.I want to create @lists based on the $scalars in @type. However, "my @$ext = ()"; and push (@$ext, @files); do not play nice with strict. How do I get around this?Quote:
########## some text text also includes empty lines ########## some more text ##########
Basically all sections are separated by 10 hashes and I need to somehow only print all lines in the last section (the "some more text" part in the example above"). I tried all kind of things with sed and awk but I didn't find any way to identify the last "section".
