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• Serial port determinism

  - by Matt Green

  This seems like a simple question, but it is difficult to search for. I need to interface with a device over the serial port. In the event my program (or another) does not finish writing a command to the device, how do I ensure the next run of the program can successfully send a command? Example: The foo program runs and begins writing "A_VERY_LONG_COMMAND" The user terminates the program, but the program has only written, "A_VERY" The user runs the program again, and the command is resent. Except, the device sees "A_VERYA_VERY_LONG_COMMAND," which isn't what we want. Is there any way to make this more deterministic? Serial port programming feels very out-of-control due to issues like this.

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• How much more productive are three monitors than two?

  - by Sir Graystar

  I am mulling over whether to buy a new monitor, to go along side my current setup of two 24 (ish) inch monitors. What I want to know is whether this is worth the money (probably around £200)? I think most of us will agree that two monitors is much more productive than one when programming and developing (Jeff Atwood has said this many times on his blog, and I imagine that most of you are fans of his), but is three much more productive than two? What I'm worried about is that I will have so much space that one monitor will be used for things that are not related to the task (music, facebook etc.) and it will actually make me less productive.

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• Pentium Assembly Code Question

  - by leon

  Hi I am new to Pentium assembly programming. Could you check if I am doing the translation of C to assembly correctly? Condition: 32-bit addresses, 32 bit integers and 16 bit characters. char[5] vowels="aeiou"; Translate: vowels db "aeoiu" ; or should it be "vowels dw "aeoiu" ? How to access vowels[p]? Is it byte[vowels+p*2]? (since characters are 16 bit? ) Many thanks

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• what great software engineers know or aspiring ones should know?

  - by trojanwarrior3000

  I do not mean any particular language or methodology. But basics( one have abstracted from ones experience and interaction with smarter people in this field) one should have including concepts, practical issues, tips/techniques/tricks one should be aware of.For example the lessons or ideas may relate to programming,testing,design,project schedules, that are really useful in daily life of software engineer/developer etc ? This may be a good question because it looks not to specific, however experience of many is better than reading from books.I find discussions much helpful than books.Hope every one will have some lessons/ideas to contribute.please substantiate with atleast one example.

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• Pipe implementation

  - by nunos

  I am trying to implement a linux shell that supports piping. I have already done simple commands, commands running in background, redirections, but piping is still missing. I have already read about it and seen some snippets of code, but still haven't been able to sort out a working solution. What I have so far: int fd[2]; pid_t pid = fork(); if (pid == -1) return -1; if (pid == 0) { dup2(0, fd[0]); execlp("sort", "sort", NULL); } I am a novice programmer, as you can probably tell, and when I am programming something I don't know much about, this being obviously the case, I like to start with something really easy and concrete and then build from there. So, before being able to implement three and more different commands in pipeline, I would like to be able to compute "ls names.txt | sort" or something similiar, in which names.txt is a file of names alfabetically unordered. Thanks.

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• (iPhone SDK) How to link instance variables to a specific UILabel

  - by Timbo

  I'm using the iPhone SDK to build a simple application. I've created a brand new class which has a single variable. I need to make 5 instances of that class, which I have no trouble doing. I can create those instances and also set the variables without issue. What i do need to know is this: How do I link each of the 5 different instances of the variable to different and specific UILabels? Would I be better to create a method that dynamically creates and positions the labels? Thanks for your help in advance, I'm now to this iphone programming thing. I'm serious about learning fast though so I have posted a bounty on this question here : http://www.askearn.com/Responses.aspx?QuestionID=6542613f-7be8-4bb3-a950-aac218d47711

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• Confused by Perl grep function

  - by titaniumdecoy

  I don't understand the last line of this function from Programming Perl 3e. Here's how you might write a function that does a kind of set intersection by returning a list of keys occurring in all the hashes passed to it: @common = inter( \%foo, \%bar, \%joe ); sub inter { my %seen; for my $href (@_) { while (my $k = each %$href) { $seen{$k}++; } } return grep { $seen{$_} == @_ } keys %seen; } I understand that %seen is a hash which maps each key to the number of times it was encountered in any of the hashes provided to the function.

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• How is thread synchronization implemented, at the assembly language level?

  - by Martin

  While I'm familiar with concurrent programming concepts such as mutexes and semaphores, I have never understood how they are implemented at the assembly language level. I imagine there being a set of memory "flags" saying: lock A is held by thread 1 lock B is held by thread 3 lock C is not held by any thread etc But how is access to these flags synchronized between threads? Something like this naive example would only create a race condition: mov edx, [myThreadId] wait: cmp [lock], 0 jne wait mov [lock], edx ; I wanted an exclusive lock but the above ; three instructions are not an atomic operation :(

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• Advice needed from PHP/Cake PHP expert

  - by Hiro

  I'm very new to programming (besides SQL and databases), but I ultimately want to master Cake PHP for web development. Now, given how new I am, I'm rather lost as to how I get started. Down the road, I want to use MVC framework so that I help myself be disciplined in the way I build. However, I know basic knowledge of PHP and OOP PHP are required. So my question is this: what are the right steps to mastering Cake PHP? I don't want to skip critical phases of learning before learning to Cake PHP. At the same time, I don't want to spend more time than required learning PHP if I can learn it directly through Cake PHP knowledge. Any advice would be appreciated.

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• How to make an existing socket fail?

  - by Huckphin

  OK. So, this is exactly the opposite of what everyone asks about in network programming. Usually, people ask how to make a broken socket work. I, on the other hand am looking for the opposite. I currently have sockets working fine, and want them to break to re-create this problem we are seeing. I am not sure how to go about intentionally making the socket fail by having a bad read. The trick is this: The socket needs to be a working, established connection, and then it must fail for whatever reason. I'm writing this in C and the drivers are running on a Linux system. The sockets are handled by a non-IP Level 3 protocol in Linux by a Linux Device Driver. I have full access to all of the code-base, I just need to find a way to tease it out so that it can fail. Any ideas?

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• Math: How to sum each row of a matrix

  - by macek

  I have a 1x8 matrix of students where each student is a 4x1 matrix of scores. Something like: SCORES S [62, 91, 74, 14] T [59, 7 , 59, 21] U [44, 9 , 69, 6 ] D [4 , 32, 28, 53] E [78, 99, 53, 83] N [48, 86, 89, 60] T [56, 71, 15, 80] S [47, 67, 79, 40] Main question: Using sigma notation, or some other mathematical function, how can I get a 1x8 matrix where each student's scores are summed? # expected result TOTAL OF SCORES S [241] T [146] U [128] D [117] E [313] N [283] T [222] S [233] Sub question. To get the average, I will multiply the matrix by 1/4. Would there be a quicker way to get the final result? AVERAGE SCORE S [60.25] T [36.50] U [32.00] D [29.25] E [78.25] N [70.75] T [55.50] S [58.25] Note: I'm not looking for programming-related algorithms here. I want to know if it is possible to represent this with pure mathematical functions alone.

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• How are SaaS/Mult-Tenancy apps implementing email notifications (sending and receving)?

  - by Mark Redman

  Given multi-tenant application, How are vendors implementing email notifications from an email account setup and programming perspective: Sending emails could come from a generic account: eg [email protected] or [email protected], this seems reasonable considering reply addresses and lilnks can be contained within the email contents. Receiving Emails: How would an application receive email, for instance; to generate support tickets or assign comments in an email to a project/task. I have seen ID's within the subject and some reply to addresses containing the account name eg: [email protected] I realise one can programatically connect to a pop3 server and receive emails and look for the IDs with the subject, but is there a way of setting up and receiving email to a single pop3 account from multiple sub-host name email addresses (not sure on terminology there) eg: [email protected] or [email protected] and check the Account Name from the address? (similar to checking subdomains on a URL) Any practices, experience, comments or sughestions? (not sure its relevant, but using C# asp.net-mvc and services etc)

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• C# differences between Windows Mobile and regular Windows

  - by Matt

  Are there many differences between Windows and Windows Mobile as far as C# programming is concerned? I can write some moderately complicated programs in C#, but I'm not sure if it would just run perfectly on a Windows smartphone, or if something has to be done to port it. If so, is there a tool that will automatically revise code to make it mobile-compatible? The reason I ask is that the new Windows mobile 7 will only support a few methods of app development, one of which is C#. Also, do smartphones with non-windows operating systems have C# support available? Or can C# code be converted to Symbian or iPhone or whatever? Thanks for any help you can provide.

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• Looking for the most painless non-RDBMS storage method in C#

  - by NateD

  I'm writing a simple program that will run entirely client-side. (Desktop programming? do people still do that?) and I need a simple way to store trivial amounts of data in a structured form, but really don't see any need to use a database system. What's more, some of the data needs to be serialized and passed around to different users, like some kind of "file" or perhaps a "document". (has anyone ever done that before?) So, I've looked at using .Net DataSets, LINQ, direct XML manipulation, and they all seem like they would get the job done, but I would like to know before I dive into any of them if there's one method that is generally regarded as easier to code than others. As I said, the amount of data to be stored is trivial, even if one hundred people all used the same machine we're not talking about more than 10 MB, so performance is not as large a concern as is codeability/maintainability. Thank you all in advance!

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• C# Class Design Question

  - by Soo

  This is a super newbie question, I've been programming for a while, but am just learning OOP. I have a class that works with user input via the C# console. There are different methods in this class to gather different input sets. I have another class that takes these input sets and puts them in a database. What is the best way to pass the input from my input class to my database insert class? My guess would be: Array1[] = inputClass.GetParameterSet1(); DatabaseInsertClass.InsertIntoDatabase1(Array1[]); Is there anything wrong with this or is there a better way to do this? Should I even have two classes (The database class could also take the user input)?

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• Recommend a PHP framework for new PHP programmer

  - by webworm

  Hi All, I am fairly new to PHP but not programming in general. I was hoping I could get some suggestions on the best type of PHP framework to start with considering my basic experience with PHP. I have a .NET and ASP.NET background and I am familiar with the MVC design pattern. I would prefer to start with a framework that makes logical design easier but does not generate all the code for you. I have read some like the Zend framework for this. Opinions?

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• How do I check if a user is authenticated with NickServ using POE::Component::IRC::State in Perl?

  - by Troy

  I'm trying to test whether a user is registered on FreeNode. nick_info() doesn't seem to return information about this, so I want to use $irc-yield(whois = $nick); and then grab the irc_whois event's reply. The problem is that I want to wait until this event is fired, so I created a global variable $whois_result and wrote a sub like this: sub whois { my $nick = $_[0]; $whois_result = 0; $irc->yield(whois => $nick); while($whois_result == 0) { } return $whois_result; } with the irc_whois handler looking like: sub on_whois { $whois_result = $_[ARG0]; print "DEBUG: irc_whois fired.\n"; } Unfortunately, the event can't fire while the loop is running so this hangs. I'm sure there's a better way to do this, but I'm not familiar enough with this kind of programming to know. Any help would be greatly appreciated.

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• OS X contains heapsort in stdlib.h which conflicts with heapsort in sort library

  - by CryptoQuick

  I'm using Ariel Faigon's sort library, found here: http://www.yendor.com/programming/sort/ I was able to get all my code working on Linux, but unfortunately, when trying to compile with GCC on Mac, its default stdlib.h contains another heapsort, which unfortunately results in a conflicting types error. Here's the man page for Apple heapsort: http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man3/heapsort.3.html Commenting out the heapsort in the sort library header causes a whole heap of problems. (pardon the pun) I also briefly thought of commenting out my use of stdlib.h, but I use malloc and realloc, so that won't work at all. Any ideas?

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• Java swing examples - Ants running around a world getting food from piles?

  - by Charlie

  I haven't done any swing programming in a while, so I'm looking for some GUI examples that are at least close to what I'm trying to do. The gui that I'll need to be representing is small nodes (let's say ants) travelling around collecting food from food piles (which just means small nodes travelling to bigger nodes). Once the node (ant) takes a piece of food, the pile shrinks a bit and the ant takes it back home (to ANOTHER circle). This SOUNDS pretty trivial, but all of the boilerplate involved in setting up a java GUI just makes little logical sense to me, and the GUI is such a small piece of my project. Any examples that would be great for this style of project would be greatly appreciated. Thanks!

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• Different NSTimeZone names being returned

  - by Michael Waterfall

  I've noticed that on some devices the NSTimeZone's name method for a particular timezone can return different values. When testing the Brisbane time zone, my device returns @"Australia/Brisbane" whereas another user's device returns "Etc/GMT-10". Both iPhone's are running 3.1.2. The Date and Time Programming Guide for Cocoa states that: timeZoneWithName: The name passed to this method may be in any of the formats understood by the system, for example EST, Etc/GMT-2, America/Argentina/Buenos_Aires, Europe/Monaco, or US/Pacific, as shown in the following code fragment. I'd just like to know what could determine which value is used? The device? The language?

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• How can I reverse a stack?

  - by come pollinate me

  I need to write a VB.NET code to reverse the given characters using a stack. Input: 'S','T','A','C','K' So far I have input the letters, but I don't know how to get the console to reverse it. I'm a beginner to programming so please excuse my ignorance. An explanation as to how it's done would also be greatly appreciated. What I got so far. Module Module1 Sub Main() Dim StackObject As New Stack StackObject.Push("S") Console.WriteLine(StackObject.Peek) StackObject.Push("T") Console.WriteLine(StackObject.Peek) StackObject.Push("A") Console.WriteLine(StackObject.Peek) StackObject.Push("C") Console.WriteLine(StackObject.Peek) StackObject.Push("K") Console.WriteLine(StackObject.Peek) End Sub End Module I just need it to be reversed. I got it!! Module Module1 Sub Main() Dim StackObject As New Stack StackObject.Push("S") StackObject.Push("T") StackObject.Push("A") StackObject.Push("C") StackObject.Push("K") For Each cur As String In StackObject Console.WriteLine(cur) Next End Sub End Module That's how it's done.

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• Groovy 1.7 changes "final"?

  - by Aaron L. Carlow

  Just started learning Groovy, got the PragProg book "Programming Groovy" and had a problem compiling one of the sample scripts: class GCar2 { final miles = 0 def getMiles() { println "getMiles called" miles } def drive(dist) { if (dist > 0) { miles += dist } } } def car = new GCar2() println "Miles: $car.miles" println 'Driving' car.drive(10) println "Miles: $car.miles" try { print 'Can I see the miles? ' car.miles = 12 } catch (groovy.lang.ReadOnlyPropertyException ex) { println ex.message GroovyCar2.groovy: 20: cannnot access final field or property outside of constructor. @ line 20, column 35. def drive(dist) { if (dist > 0) miles += dist } ^ Groovy versions prior to 1.7 do not give an error. I looked through whatever documentation I could find and did not see the issue discussed. What is going on here? Aaron

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• Separating arguments to a function, in locales with comma as decimal marker

  - by Chris Pousset

  In locales, e.g. French, with comma as decimal indicator (where "5,2" means five and two-tenths), how do users separate function arguments from each other? For example, in many programming/scripting languages, I could specify MAX(1.5, X) in a EN-US locale. How do you avoid the ambiguity between the comma as decimal indicator, and as argument separator? In particular, I'm interested in how software that's perceived as user-friendly in the foreign locale does it. Obviously, it's a no-brainer to say, "thou shalt use decimal POINTs", but that's not particularly "friendly".

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• How is joystick axis information formatted from a USB Joystick?

  - by aquanar

  I actually just have a rather small question, but I have had the HARDEST time finding information about it. For the application I am programming for, there will be a 3-axis joystick being connected via USB to a Windows XP computer, and it is being handled by directx. That information will then be sent elsewhere to an embedded controller. I don't need to know too much of the intricacies of how directx handles it, but I want to know, how is the data for the axes formatted? Nearest I can tell, most joysticks nowadays have 12 bits of resolution, so is the data output as a 12-bit 2's compliment number? And after that, is it represented as a signed 16-bit integer when it is captured from directx? I'd like to know this so I know how I will work with the data at the embedded platform side, such as how to format the packets sending data to the embedded side, as well ashow to use the information once it is on the embedded side.

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• Assignment to None

  - by Joel

  Hello, I have a function which returns 3 numbers, e.g.: def numbers(): return 1,2,3 usually I call this function to receive all three returned numbers e.g.: a,b,c=numbers() However, I have one case in which I only need the first returned number. I tried using: a, None None = numbers() But I receive "SyntaxError: assignment to None". I know, of course, that i can use the first option I mentioned and then not use "b" and "c", but only "a". However, this seems like a "waste" of two vars and feels like wrong programming. Any ideas? Thanks, Joek

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