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  • perl hashes - comparing keys and values

    - by Aaron Moodie
    I've been reading over the perl doc, but I can't quite get my head around hashes. I'm trying to find if a hash key exists, and if so, compare is't value. The thing that is confusing me is that my searches say that you find if a key exists by if (exists $files{$key}) , but that $files{$key} also gives the value? the code i'm working on is: foreach my $item(@new_contents) { next if !-f "$directory/$item"; my $date_modified = (stat("$directory/$item"))[9]; if (exists $files{$item}) { if ($files{$item} != $date_modified { $files{$item} = $date_modified; print "$item has been modified\n"; } } else { $files{$item} = $date_modified; print "$item has been added\n"; } }

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  • Why do I not get the correct answer for Euler 56 in J?

    - by Gregory Higley
    I've solved 84 of the Project Euler problems, mostly in Haskell. I am now going back and trying to solve in J some of those I already solved in Haskell, as an exercise in learning J. Currently, I am trying to solve Problem 56. Let me stress that I already know what the right answer is, since I've already solved it in Haskell. It's a very easy, trivial problem. I will not give the answer here. Here is my solution in J: digits =: ("."0)":"0 eachDigit =: adverb : 'u@:digits"0' NB. I use this so often I made it an adverb. cartesian =: adverb : '((#~ #) u ($~ ([:*~#)))' >./ +/ eachDigit x: ^ cartesian : i. 99 This produces a number less than the desired result. In other words, it's wrong somehow. Any J-ers out there know why? I'm baffled, since it's pretty straightforward and totally brute force.

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  • What is the single most influential book every programmer should read?

    - by NotMyself
    If you could go back in time and tell yourself to read a specific book at the beginning of your career as a developer, which book would it be? I expect this list to be varied and to cover a wide range of things. For me, the book would be Code Complete. After reading that book, I was able to get out of the immediate task mindset and begin to think about the bigger picture, quality and maintainability.

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  • How does PHP work - literature

    - by Ondrej Slinták
    I'm interested in literature (articles on internet, in magazines, books, podcasts - I don't really mind anything) that describes how PHP works internally, about its gotchas and perhaps some advanced functions. Is there anything like this out there? I tried to search on Google, but majority of articles were about starting with PHP and its basic functions. Any input is really welcome as I'm trying to understand the language internally - I'm tired of my mindless typing of code without understanding its essence.

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  • How to retrieve Directories size including all sub-directories?

    - by vikingosegundo
    I have stored images from the net like this Documents/imagecache/domain1/original/path/inURI/foo.png Documents/imagecache/domain2/original/path/inURI/bar.png Documents/imagecache/... Documents/imagecache/... Now I'd like to check the size of imagecache including all it sub-directories. Is there a convenient way of doing it — preferable without crawling through all the data manually?

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  • Linking IronPython to WPF

    - by DonnyD
    I just installed VS2010 and the great new IronPython Tools extension. Currently this extension doesn't yet generate event handlers in code upon double-clicking wpf visual controls. Is there anyone that can provide or point me to an example as to how to code wpf event handlers manually in python. I've had no luck finding any and I am new to visual studio. Upon generating a new ipython wpf project the auto-generated code is: import clr clr.AddReference('PresentationFramework') from System.Windows.Markup import XamlReader from System.Windows import Application from System.IO import FileStream, FileMode app = Application() app.Run(XamlReader.Load(FileStream('WpfApplication7.xaml', FileMode.Open))) and the XAML is: <Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="WpfApplication7" Height="300" Width="300"> <Button>Click Me</Button> </Window> Any help would be appreciated.

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  • How do you setLayoutParams() for an ImageView?

    - by DeadTime
    I want to set the LayoutParams for an ImageView but cant seem to find out the proper way to do it. I can only find documentation in the API for the various ViewGroups, but not an ImageView. Yet the ImageView seems to have this functionality. This code doesn't work... myImageView.setLayoutParams(new ImageView.LayoutParams(30,30)); How do I do it?

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  • SQL Express Edition, SQL Compact Editin and SQLCMD for learning purpose

    - by Mil
    Hi, I want to learn programming in SQL from some SQL tutorial sites of which I heard of here but I need some environment for executing query's. I think I have both SQL CE and SQL EE installed on my computer but I have some doubts about these DBMS and I don't know exactly how to use SQLCMD utility so I hope someone here will have time and will to explain me the following: Since running sqlcmd -S.\sqlexpress at command prompt command gives "1" prompt I assume I have SQL express installed but anyway how can I be sure what I have installed on my machine since I cannot find in installed programs SQL Express Edition name? Can I ship and use database with my C# (VC# Express) application which was created with SQL EE (embedded?)? How can use sqlcmd for learning SQL, that is by issuing commands like create, use, select..., again emphasize is on learning SQL I do not want to run scripts but use interactive command prompt like with MySQL (since I want to use SQL I would pretty much like to avoid graphical tools for DBMS)? Please tell me if you have some other advice regarding as to what should I better use in learning how to program in SQL or should I stick with the above for now. Thanks in advance.

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  • Basic Array Iteration in Ruby

    - by michaelmichael
    What's a better way to traverse an array while iterating through another array? For example, if I have two arrays like the following: names = [ "Rover", "Fido", "Lassie", "Calypso"] breeds = [ "Terrier", "Lhasa Apso", "Collie", "Bulldog"] Assuming the arrays correspond with one another - that is, Rover is a Terrier, Fido is a Lhasa Apso, etc. - I'd like to create a dog class, and a new dog object for each item: class Dog attr_reader :name, :breed def initialize(name, breed) @name = name @breed = breed end end I can iterate through names and breeds with the following: index = 0 names.each do |name| dog = Dog.new("#{name}", "#{breeds[index]}") index = index.next end However, I get the feeling that using the index variable is the wrong way to go about it. What would be a better way?

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  • Compile/use unrar C++ source for iphone app?

    - by greypoint
    Writing an app that will include the ability to decompress zip and rar files. I think I'm OK on how to handle the .zips but .rars seem a little more trouble. I noticed that rarlabs has source available but it's C++. Is there a way to compile, wrap or otherwise use this code within an iPhone app? Reference: http://www.rarlab.com/rar_add.htm Open to alternate suggestions on how to handle .rar files as well. I'm still pretty much a newbie so please explain in small words :)

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  • SQLiteDataAdapter Update method returning 0

    - by Lirik
    I loaded 83 rows from my CSV file, but when I try to update the SQLite database I get 0 rows... I can't figure out what I'm doing wrong. The program outputs: Num rows loaded is 83 Num rows updated is 0 The source code is: public void InsertData(String csvFileName, String tableName) { String dir = Path.GetDirectoryName(csvFileName); String name = Path.GetFileName(csvFileName); using (OleDbConnection conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + dir + @";Extended Properties=""Text;HDR=Yes;FMT=Delimited""")) { conn.Open(); using (OleDbDataAdapter adapter = new OleDbDataAdapter("SELECT * FROM " + name, conn)) { QuoteDataSet ds = new QuoteDataSet(); adapter.Fill(ds, tableName); Console.WriteLine("Num rows loaded is " + ds.Tags.Rows.Count); InsertData(ds, tableName); } } } public void InsertData(QuoteDataSet data, String tableName) { using (SQLiteConnection conn = new SQLiteConnection(_connectionString)) { using (SQLiteDataAdapter sqliteAdapter = new SQLiteDataAdapter("SELECT * FROM " + tableName, conn)) { using (new SQLiteCommandBuilder(sqliteAdapter)) { conn.Open(); Console.WriteLine("Num rows updated is " + sqliteAdapter.Update(data, tableName)); } } } } Any hints on why it's not updating the correct number of rows?

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  • make include directive and dependency generation with -MM

    - by Robert S. Barnes
    I want a build rule to be triggered by an include directive if the target of the include is out of date or doesn't exist. Currently the makefile looks like this: program_NAME := wget++ program_H_SRCS := $(wildcard *.h) program_CXX_SRCS := $(wildcard *.cpp) program_CXX_OBJS := ${program_CXX_SRCS:.cpp=.o} program_OBJS := $(program_CXX_OBJS) DEPS = make.deps .PHONY: all clean distclean all: $(program_NAME) $(DEPS) $(program_NAME): $(program_OBJS) $(LINK.cc) $(program_OBJS) -o $(program_NAME) clean: @- $(RM) $(program_NAME) @- $(RM) $(program_OBJS) @- $(RM) make.deps distclean: clean make.deps: $(program_CXX_SRCS) $(program_H_SRCS) $(CXX) $(CPPFLAGS) -MM $(program_CXX_SRCS) > make.deps include $(DEPS) The problem is that it seems like the include directive is executing before the rule to build make.deps which effectively means make either getting no dependency list if make.deps doesn't exist or always getting the make.deps from the previous build and not the current one. For example: $ make clean $ make makefile:32: make.deps: No such file or directory g++ -MM addrCache.cpp connCache.cpp httpClient.cpp wget++.cpp > make.deps g++ -c -o addrCache.o addrCache.cpp g++ -c -o connCache.o connCache.cpp g++ -c -o httpClient.o httpClient.cpp g++ -c -o wget++.o wget++.cpp g++ addrCache.o connCache.o httpClient.o wget++.o -o wget++

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  • How should a programmer go about getting started with Flash/Flex/ActionScript?

    - by Graphics Noob
    What is the shortest path between zero (ie no flash related development software on my computer or information about where to obtain it or get started) to running a "hello world" ActionScript? I'm hoping for an answer that gives step by step instructions about exactly what software is needed to get started, an example of some "hello world" code, and instructions for compiling and running the code. I've spent more time than I think should be necessary researching this question and not found much information. Hopefully this question will be found by programmers like me who want to get started with Flash/Flex/ActionScript (After my morning of researching I still don't even know what terminology to use so I'll just throw it all out there). ActionScript tutorials I've found are focused on programming concepts, ie logic, branching, OOP, etc, and some even have code examples to download, but not a single one I've found explains how to compile and run the code. They all seem to assume you have an IDE standing by but no knowledge of programming, exactly the opposite of the position I'm in. Here are the most related SO questions I've found: http://stackoverflow.com/questions/59083/what-is-adobe-flex-is-it-just-flash-ii http://stackoverflow.com/questions/554899/getting-started-with-flex-3-ui-actionscript-programming http://stackoverflow.com/questions/2123105/how-to-learn-flex

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  • What is a monad?

    - by kronoz
    Having briefly looked at Haskell recently I wondered whether anybody could give a brief, succinct, practical explanation as to what a monad essentially is? I have found most explanations I've come across to be fairly inaccessible and lacking in practical detail, so could somebody here help me?

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  • Is there a better (i.e vectorised) way to put part of a column name into a row of a data frame in R

    - by PaulHurleyuk
    I have a data frame in R that has come about from running some stats on the result fo a melt/cast operation. I want to add a row into this dataframe containing a Nominal value. That Nominal Value is present in the names for each column df<-as.data.frame(cbind(x=c(1,2,3,4,5),`Var A_100`=c(5,4,3,2,1),`Var B_5`=c(9,8,7,6,5))) > df x Var A_100 Var B_5 1 1 5 9 2 2 4 8 3 3 3 7 4 4 2 6 5 5 1 5 So, I want to create a new row, that contains '100' in the column Var A_100 and '5' in Var B_5. Currently this is what I'm doing but I'm sure there must be a better, vectorised way to do this. temp_nom<-NULL for (l in 1:length(names(df))){ temp_nom[l]<-strsplit(names(df),"_")[[l]][2] } temp_nom [1] NA "100" "5" df[6,]<-temp_nom > df x Var A_100 Var B_5 1 1 5 9 2 2 4 8 3 3 3 7 4 4 2 6 5 5 1 5 6 <NA> 100 5 rm(temp_nom) Typically I'd have 16-24 columns. Any ideas ?

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  • How do I make lines scale when using GLOrtho?

    - by Mason Wheeler
    I'm using GLOrtho to set up a 2D view that I can render textures onto. It works really well, up until I try to zoom in on the image. If I pass half the width and half the height of the viewport to GLOrtho, I end up with all my textures displayed twice as big as normal, which is exactly what I expect. But then I try to draw a box around part of the image and it all falls apart. I call glBegin(GL_LINE_LOOP), place the four vertices, and call glEnd, and I expect to see the same thing I would see if I drew it at normal zoom level, doubled. Instead, I get lines that are all the right length, but they all come out one pixel wide, instead of two, and it looks really bad. What am I missing?

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  • How can I generate the Rowland prime sequence idiomatically in J?

    - by Gregory Higley
    If you're not familiar with the Rowland prime sequence, you can find out about it here. I've created an ugly, procedural monadic verb in J to generate the first n terms in this sequence, as follows: rowland =: monad define result =. 0 $ 0 t =. 1 $ 7 while. (# result) < y do. a =. {: t n =. 1 + # t t =. t , a + n +. a d =. | -/ _2 {. t if. d > 1 do. result =. ~. result , d end. end. result ) This works perfectly, and it indeed generates the first n terms in the sequence. (By n terms, I mean the first n distinct primes.) Here is the output of rowland 20: 5 3 11 23 47 101 7 13 233 467 941 1889 3779 7559 15131 53 30323 60647 121403 242807 My question is, how can I write this in more idiomatic J? I don't have a clue, although I did write the following function to find the differences between each successive number in a list of numbers, which is one of the required steps. Here it is, although it too could probably be refactored by a more experienced J programmer than I: diffs =: monad : '}: (|@({.-2&{.) , $:@}.) ^: (1 < #) y'

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  • Getting logging.debug() to work on Google App Engine/Python

    - by brainjam
    I'm just getting started on building a Python app for Google App Engine. In the localhost environment I'm trying to send debug info to the GoogleAppEngineLauncher Log Console via logging.debug(), but it isn't showing up. However, anything sent through, say, logging.info() or logging.error() does show up. I've tried a logging.basicConfig(level=logging.DEBUG) before the logging.debug(), but to no avail. What am I missing?

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