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• What pitfalls (if any) are there to learning C/C++ as a first language?

  - by thyrgle

  Hi, I first learned C++ then moved to C (I know kind of backwards) and then I found a thing called iTunes U and began watching programming classes to extend my knowledge and noticed that Stanford and MIT both did not teach C or C++ as an introduction to computer programming. Then I began to wonder why they didn't begin teaching C/C++ because I thought C/C++ was more efficient than Java (which Stanford taught) and Python (which MIT taught). Or maybe there is no particular reason?

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• Part-time Programming Job

  - by Bluechip Solutions

  I am a student at Middlesex Universtity, London studying Information Technology. I really love software development and I have taught myself how to write HTML + CSS, JavaScript (I use jQuery and AngularJS) and Java (I learnt this in school). I have developed few apps (a desktop app in Java and a mobile app with AngularJS and PhoneGap) I am looking at applying for a part-time programming job to develop myself. Are there part time jobs available for someone like me and are my skill set enough to get me a job? I understand this topic may not be ideal here but this is the only place I know can provide me answers. Thank you!

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• Question about using ServiceModelEx's "WCFLogbook" from "Programming WCF Services" book

  - by Bill

  I am attempting to compile/run a sample WCF application from Juval Lowy's website (author of Programming WCF Services & founder of IDesign). Of course the example application utilizes Juval's ServiceModelEx library and logs faults/errors to a "WCFLogbook" database. Unfortunately, when the sample app faults, I get the following new error: "Cannot open database "WCFLogbook" requested by the login. The login failed. Login failed for user 'Bill-PC\Bill'." I suspect the error occurs as a result of not finding the "WCFLogbook" database, which I believe still needs to be created. Included in the library source directory, there are two files -WCFLogbookDataSet.xsd and WCFLogbook.sql; which neither seem to be referenced anywhere within the library code. This leads me to beleive that the sql and xsd files are there to be used to create the database somehow in SQL. Could someone please advise me if I am going in the correct direction here and if whether these files can be used to create the database (and if so, how)?

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• Setting the Classpath and Accessing code from book: Programming Clojure

  - by user130153

  (I posted this same question on the Clojure list but haven't got an answer yet. Is anyone here ready to help?) I am going through Programming Clojure and I recently downloaded the code from the books official website. For other utils I can do, for example, (require 'clojure.contrib.str-utils) and it works. But how do I load code from the book? (require 'examples.introduction) throws the following exception: java.io.FileNotFoundException: Could not locate examples/ introduction__init.class or examples/introduction.clj on classpath: (NO_SOURCE_FILE:0) [Thrown class clojure.lang.Compiler$CompilerException] Here is the full backtrace: Backtrace: 0: clojure.lang.Compiler.eval(Compiler.java:4543) 1: clojure.core$eval__3990.invoke(core.clj:1728) 2: swank.commands.basic$eval_region__686.invoke(basic.clj:36) 3: swank.commands.basic$listener_eval__695.invoke(basic.clj:50) 4: clojure.lang.Var.invoke(Var.java:346) 5: user$eval__1200.invoke(NO_SOURCE_FILE) 6: clojure.lang.Compiler.eval(Compiler.java:4532) 7: clojure.core$eval__3990.invoke(core.clj:1728) 8: swank.core$eval_in_emacs_package__307.invoke(core.clj:55) 9: swank.core$eval_for_emacs__384.invoke(core.clj:123) 10: clojure.lang.Var.invoke(Var.java:354) 11: clojure.lang.AFn.applyToHelper(AFn.java:179) 12: clojure.lang.Var.applyTo(Var.java:463) 13: clojure.core$apply__3243.doInvoke(core.clj:390) 14: clojure.lang.RestFn.invoke(RestFn.java:428) 15: swank.core$eval_from_control__310.invoke(core.clj:62) 16: swank.core$eval_loop__313.invoke(core.clj:67) 17: swank.core$spawn_repl_thread__445$fn__476$fn__478.invoke(core.clj: 173) 18: clojure.lang.AFn.applyToHelper(AFn.java:171) 19: clojure.lang.AFn.applyTo(AFn.java:164) 20: clojure.core$apply__3243.doInvoke(core.clj:390) 21: clojure.lang.RestFn.invoke(RestFn.java:428) 22: swank.core$spawn_repl_thread__445$fn__476.doInvoke(core.clj:170) 23: clojure.lang.RestFn.invoke(RestFn.java:402) 24: clojure.lang.AFn.run(AFn.java:37) 25: java.lang.Thread.run(Unknown Source) I am trying both Clojure Box and Enclojure in NetBeans on Windows XP. Is it a classpath issue? Where should I place the folder that contains code from the book? Please help me out with my variable enviroment settings as well.

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• Question on Scala Closure (From "Programming in Scala")

  - by Ekkmanz

  I don't understand why authors said that Code Listing 9.1 from "Programming in Scala" use closure. In chapter 9, they show how to refactor code into more less duplicated form, from this original code: object FileMatcher { private def filesHere = (new java.io.File(".")).listFiles def filesEnding(query: String) = for (file <- filesHere; if file.getName.endsWith(query)) yield file def filesContaining(query: String) = for (file <- filesHere; if file.getName.contains(query)) yield file def filesRegex(query: String) = for (file <- filesHere; if file.getName.matches(query)) yield file } To the second version: object FileMatcher { private def filesHere = (new java.io.File(".")).listFiles def filesMatching(query: String, matcher: (String, String) => Boolean) = { for (file <- filesHere; if matcher(file.getName, query)) yield file } def filesEnding(query: String) = filesMatching(query, _.endsWith(_)) def filesContaining(query: String) = filesMatching(query, _.contains(_)) def filesRegex(query: String) = filesMatching(query, _.matches(_)) } Which they said that there is no use of closure here. Now I understand until this point. However they introduced the use of closure to refactor even some more, shown in Listing 9.1: object FileMatcher { private def filesHere = (new java.io.File(".")).listFiles private def filesMatching(matcher: String => Boolean) = for (file <- filesHere; if matcher(file.getName)) yield file def filesEnding(query: String) = filesMatching(_.endsWith(query)) def filesContaining(query: String) = filesMatching(_.contains(query)) def filesRegex(query: String) = filesMatching(_.matches(query)) } Now they said that query is a free variable but I don't really understand why they said so? Since ""query"" seems to be passed from top method down to string matching function explicitly.

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• Dynamic programming in VB

  - by Rahul Jain

  Hello Everybody, We develop applications for SAP using their SDK. SAP provides a SDK for changing and handling events occuring in the user interface. For example, with this SDK we can catch a click on a button and do something on the click. This programming can be done either VB or C#. This can also be used to create new fields on the pre-existing form. We have developed a specific application which allows users to store the definition required for new field in a database table and the fields are created at the run time. So far, this is good. What we require now is that the user should be able to store the validation code for the field in the database and the same should be executed on the run time. Following is an example of such an event: Private Sub SBO_Application_ItemEvent(ByVal FormUID As String, ByRef pVal As SAPbouiCOM.ItemEvent, ByRef BubbleEvent As Boolean) Handles SBO_Application.ItemEvent Dim oForm As SAPbouiCOM.Form If pVal.FormTypeEx = "ACC_QPLAN" Then If pVal.EventType = SAPbouiCOM.BoEventTypes.et_LOST_FOCUS And pVal.BeforeAction = False Then oProdRec.ItemPressEvent(pVal) End If End If End Sub Public Sub ItemPressEvent(ByRef pVal As SAPbouiCOM.ItemEvent) Dim oForm As SAPbouiCOM.Form oForm = oSuyash.SBO_Application.Forms.GetForm(pVal.FormTypeEx, pVal.FormTypeCount) If pVal.EventType = SAPbouiCOM.BoEventTypes.et_LOST_FOCUS And pVal.BeforeAction = False Then If pVal.ItemUID = "AC_TXT5" Then Dim CardCode, ItemCode As String ItemCode = oForm.Items.Item("AC_TXT2").Specific.Value CardCode = oForm.Items.Item("AC_TXT0").Specific.Value UpdateQty(oForm, CardCode, ItemCode) End If End If End Sub So, what we need in this case is to store the code given in the ItemPressEvent in a database, and execute this in runtime. I know this is not straight forward thing. But I presume there must be some ways of getting these kind of things done. The SDK is made up of COM components. Thanks & Regards, Rahul Jain

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• Programming R/Sweave for proper \Sexpr output

  - by deoksu

  Hi I'm having a bit of a problem programming R for Sweave, and the #rstats twitter group often points here, so I thought I'd put this question to the SO crowd. I'm an analyst- not a programmer- so go easy on me my first post. Here's the problem: I am drafting a survey report in Sweave with R and would like to report the marginal returns in line using \Sexpr{}. For example, rather than saying: Only 14% of respondents said 'X'. I want to write the report like this: Only \Sexpr{p.mean(variable)}$\%$ of respondents said 'X'. The problem is that Sweave() converts the results of the expression in \Sexpr{} to a character string, which means that the output from expression in R and the output that appears in my document are different. For example, above I use the function 'p.mean': p.mean<- function (x) {options(digits=1) mmm<-weighted.mean(x, weight=weight, na.rm=T) print(100*mmm) } In R, the output looks like this: p.mean(variable) >14 but when I use \Sexpr{p.mean(variable)}, I get an unrounded character string (in this case: 13.5857142857143) in my document. I have tried to limit the output of my function to 'digits=1' in the global environment, in the function itself, and and in various commands. It only seems to contain what R prints, not the character transformation that is the result of the expression and which eventually prints in the LaTeX file. as.character(p.mean(variable)) >[1] 14 >[1] "13.5857142857143" Does anyone know what I can do to limit the digits printed in the LaTeX file, either by reprogramming the R function or with a setting in Sweave or \Sexpr{}? I'd greatly appreciate any help you can give. Thanks, David

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• "Programming In Haskell" error in sat function

  - by Matt Ellen

  I'm in chapter 8 of Graham Hutton's Programming in Haskell and I'm copying the code and testing it in GHC. See the slides here: http://www.cis.syr.edu/~sueo/cis352/chapter8.pdf in particular slide 15 The relevant code I've copied so far is: type Parser a = String -> [(a, String)] pih_return :: a -> Parser a pih_return v = \inp -> [(v, inp)] failure :: Parser a failure = \inp -> [] item :: Parser Char item = \inp -> case inp of [] -> [] (x:xs) -> [(x,xs)] parse :: Parser a -> String -> [(a, String)] parse p inp = p inp sat :: (Char -> Bool) -> Parser Char sat p = do x <- item if p x then pih_return x else failure I have changed the name of the return function from the book to pih_return so that it doesn't clash with the Prelude return function. The errors are in the last function sat. I have copied this directly from the book. As you can probably see p is a function from Char to Bool (e.g. isDigit) and x is of type [(Char, String)], so that's the first error. Then pih_return takes a value v and returns [(v, inp)] where inp is a String. This causes an error in sat because the v being passed is x which is not a Char. I have come up with this solution, by explicitly including inp into sat sat :: (Char -> Bool) -> Parser Char sat p inp = do x <- item inp if p (fst x) then pih_return (fst x) inp else failure inp Is this the best way to solve the issue?

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• What AOP tools exist for doing aspect-oriented programming at the assembly language level against x8

  - by JohnnySoftware

  Looking for a tool I can use to do aspect-oriented programming at the assembly language level. For experimentation purposes, I would like the code weaver to operate native application level executable and dynamic link libraries. I have already done object-oriented AOP. I know assembly language for x86 and so forth. I would like to be able to do logging and other sorts of things using the familiar before/after/around constructs. I would like to be able to specify certain instructions or sequences/patterns of consecutive instructions as what to do a pointcut on since assembly/machine language is not exactly the most semantically rich computer language on the planet. If debugger and linker symbols are available, naturally, I would like to be able to use them to identify subroutines' entry points , branch/call/jump target addresses, symbolic data addresses, etc. I would like the ability to send notifications out to other diagnostic tools. Thus, support for sending data through connection-oriented sockets and datagrams is highly desirable. So is normal logging to files, UI, etc. This can be done using the action part of an aspect to make a function call, but then there are portability issues so the tool needs to support a flexible, well-abstracted logging/notifying mechanism with a clean, simple yet flexible. The goal is rapid-QA. The idea is to be able to share aspect source code braodly within communties as well as publicly. So, there needs to be a declarative security policy file that users can share. This insures that nothing untoward that is hidden directly or indirectly in an aspect source file slips by the execution manager. The policy file format needs to be simple to read, write, modify, understand, type-in, edit, and generate. Sort of like Java .policy files. Think the exact opposite of anything resembling XML Schema files and you get the idea. Is there such a tool in existence already?

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• Programming tips for writing document editors?

  - by Tesserex

  I'm asking this because I'm in the process of writing two such editors for my Mega Man engine, one a tileset editor, and another a level editor. When I say document editor, I mean the superset application type for things like image editors and text editors. All of these share things like toolbars, menu options, and in the case of image editors, and my apps, tool panes. We all know there's tons of advice out there for interface design in these apps, but I'm wondering about programming advice. Specifically, I'm doubting my code designs with the following things: Many menu options toggle various behaviors. What's the proper way to reliably tie the checked state of the option with the status of the behavior? Sometimes it's more complicated, like options being disabled when there's no document loaded. More and more consensus seems to be against using MDI, but how should I control tool panes? For example, I can't figure out how to get the panels to minimize and maximize along with the main window, like Photoshop does. When tool panels are responsible for a particular part of the document, who actually owns that thing? The main window, or the panel class? How do you do communication between the tool panels and the main window? Currently mine is all event based but it seems like there could be a better way. This seems to be a common class of gui application, but I've never seen specific pointers on code design for them. Could you please offer whatever advice or experience you have for writing them?

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• Pronunciation of programming structures (particularly in c#)

  - by Andrzej Nosal

  As a non-English speaking person I often have problems pronouncing certain programming structures and abbreviations. I've been watching some video tutorials and listening to podcasts as well, though I couldn't catch them all. My question is what is the common or correct pronunciation of the following code snippets? Generics, like IEnumerable<int> or in a method void Swap<T>(T lhs, T rhs) Collections indexing and indexer access e.g. garage[i], rectangular arrays myArray[2,1] or jagged[1][2][3] Lambda operator =>, e.g. in a where extension method .Where(animal => animal.Color == Color.Brown) or in an anonymous method () => { return false;} Inheritance class Derived : Base (extends?) class SomeClass : IDisposable (implements?) Arithemtic operators += -= *= /= %= ! Are += and -= pronounced the same for events? Collections initializers new int[] { 4, 5, 8, 9, 12, 13, 16, 17 }; Casting MyEnum foo = (MyEnum)(int)yourFloat; (as?) Nullables DateTime? dt = new DateTime?(); I tagged the question with C# as some of them are specific to C# only.

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• Understanding F# Asynchronous Programming

  - by Yin Zhu

  I kind of know the syntax of asynchronous programming in F#. E.g. let downloadUrl(url:string) = async { let req = HttpWebRequest.Create(url) // Run operation asynchronously let! resp = req.AsyncGetResponse() let stream = resp.GetResponseStream() // Dispose 'StreamReader' when completed use reader = new StreamReader(stream) // Run asynchronously and then return the result return! reader.AsyncReadToEnd() } In F# expert book (and many other sources), they say like let! var = expr simply means "perform the asynchronous operation expr and bind the result to var when the operation completes. Then continue by executing the rest of the computation body" I also know that a new thread is created when performing async operation. My original understanding was that there are two parallel threads after the async operation, one doing I/O and one continuing to execute the async body at the same time. But in this example, I am confused at let! resp = req.AsyncGetResponse() let stream = resp.GetResponseStream() What happens if resp has not started yet and the thread in the async body wants to GetResponseStream? Is this a possible error? So maybe my original understanding was wrong. The quoted sentences in the F# expert book actually means that "creating a new thread, hang the current thread up, when the new thread finishes, wake up the body thread and continue", but in this case I don't see we could save any time. In the original understanding, the time is saved when there are several independent IO operations in one async block so that they could be done at the same time without intervention with each other. But here, if I don't get the response, I cannot create the stream; only I have stream, I can start reading the stream. Where's the time gained?

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• suggestions for declarative GUI programming in Java

  - by Jason S

  I wonder if there are any suggestions for declarative GUI programming in Java. (I abhor visual-based GUI creator/editor software, but am getting a little tired of manually instantiating JPanels and Boxes and JLabels and JLists etc.) That's my overall question, but I have two specific questions for approaches I'm thinking of taking: JavaFX: is there an example somewhere of a realistic GUI display (e.g. not circles and rectangles, but listboxes and buttons and labels and the like) in JavaFX, which can interface with a Java sourcefile that accesses and updates various elements? Plain Old Swing with something to parse XUL-ish XML: has anyone invented a declarative syntax (like XUL) for XML for use with Java Swing? I suppose it wouldn't be hard to do, to create some code based on STaX which reads an XML file, instantiates a hierarchy of Swing elements, and makes the hierarchy accessible through some kind of object model. But I'd rather use something that's well-known and documented and tested than to try to invent such a thing myself. JGoodies Forms -- not exactly declarative, but kinda close & I've had good luck with JGoodies Binding. But their syntax for Form Layout seems kinda cryptic. edit: lots of great answers here! (& I added #3 above) I'd be especially grateful for hearing any experiences any of you have had with using one of these frameworks for real-world applications. p.s. I did try a few google searches ("java gui declarative"), just didn't quite know what to look for.

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• Implementing Excel 2003 COM Add-in UDF in Asyc Programming model using C#(VS 2005)

  - by Venu

  Hi: I am trying to implement a UDF using Excel COM Add-in(2003) with Visual Studio 2005 in C#. I would like to implement the UDF using async programming. The UDF is a slow operation as its results are fetched from a server. As an illustration(not a real world example),the following UDF works fine without any issue: public double mul(double number1, double number2) { return number1 * number2; } How can I do the same functionality in an async way: For example, I would like the UDF return immediately and later when the results are available from a server, I would like to update the desired cells. // This method returns immediately. public object mul(double number1, double number2) { return "calculating"; } // This method of a worker thread will update the results. public OnResultsAvailable(object result) { // Question: how should I update the cells that triggerred the calcualtions above? } Constraints: I cannot use Excel RTD as I have to work with existing codebase written using Excel C# COM Add-in. Thanks for the help. -Venu

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• Concept of WNDCLASSEX, good programming habits and WndProc for system classes

  - by luiscubal

  I understand that the Windows API uses "classes", relying to the WNDCLASS/WNDCLASSEX structures. I have successfully gone through windows API Hello World applications and understand that this class is used by our own windows, but also by Windows core controls, such as "EDIT", "BUTTON", etc. I also understand that it is somehow related to WndProc(it allows me to define a function for it) Although I can find documentation about this class, I can't find anything explaining the concept. So far, the only thing I found about it was this: A Window Class has NOTHING to do with C++ classes. Which really doesn't help(it tells me what it isn't but doesn't tellme what it is). In fact, this only confuses me more, since I'd be tempted to associate WNDCLASSEX to C++ classes and think that "WNDCLASSEX" represents a control type . So, my first question is What is it? In second place, I understand that one can define a WndProc in a class. However, a window can also get messages from the child controls(or windows, or whatever they are called in the Windows API). How can this be? Finally, when is it a good programming practise to define a new class? Per application(for the main frame), per frame, one per control I define(if I create my own progress bar class, for example)? I know Java/Swing, C#/Windows.Form, C/GTK+ and C++/wxWidgets, so I'll probably understand comparisons with these toolkits.

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• Does fast typing influence fast programming? [closed]

  - by Lukasz Lew

  Many young programmers think that their bottleneck is typing speed. After some experience one realizes that it is not the case, you have to think much more than type. At some point my room-mate forced me to turn of the light (he sleeps during the night). I had to learn to touch type and I experienced an actual improvement in programming skill. The most surprising was that the improvement not due to sheer typing speed, but to a change in mindset. I'm less afraid now to try new things and refactor them later if they work well. It's like having a new tool in the bag. Have anyone of you had similar experience? Now I trained a touch typing a little with KTouch. I find auto-generate lessons the best. I can use this program to create new lessons out of text files but it's only verbatim training, not auto-generated based on a language model. Do you know any touch typing program that allows creation of custom, but randomized lessons?

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• Visual Studio and .NET programming

  - by Vit

  Hi, I just want to ask wheather I am right or not about .NET. So, .NET is new framework that enables you to easily implement new and old windows functions. It is similiar to java in the way that its also compiled into "bytecode", but its name is Common Language Infrastructure, or CLI. This language is interpreted by .NET Framework, so code generated by programming using .NET cannot be executed directly by CPU. Now, few languages can be compiled to CLI. First, it was Microsoft-developed C#, than J#, C++ others. I suspect that this is in general right, at least I hope I understand it right. But, what I am still missing is, can you write to machine code compiled code in C#? And, if using Visual Studio 2005, when I select Win32 project, it is compiled into machine code, so only thing you need to run this apps are windows dynamic-link libraries, since static libraries code is implemented into app durink linking phase. And those dynamic-link libraries are implemented in every windows installation, or provided by DirectX installations. But when I select CLR in Visual Studio 2005, than app is compiled into CLI code, and it first executes .NET framework, and than .NET framework executes that program, since its not in machine code. So, I am right? I ask becouse you can read these infos on the internet, but I have noone to tell me wheather I understand it right or not. Thanks.

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• Programming exercises in Java inheritance for intern

  - by Tenner

  I work for a small software development team, working primarily in Java, for a very large company. Our new intern showed up sight-unseen (not uncommon in my company). He has some C++ experience but no Java. Worse, he's never worked with inheritance in C++. Our code has a great deal of abstraction and a heavy reliance on inheritance. We need to get him up to speed as quickly as possible. Of course the rest of the team is busy, and so we can't take the time out of our day to teach a one-student 200-level CS course. Instead, I'd like to give him an actual programming project to work on which highlights how classes, interfaces, method overrides, etc. work. I've had him look at Project Euler, but most of the solutions end up being procedural, and not object-oriented programs. Do any of you have any somewhat-straightforward (and relatively quick) projects which you would give to an intern in this situation? Or, any recent (or current) students have a school project they'd be willing to share? Anyone else had this experience?

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• Android Layout + Programming

  - by MD

  I'm trying to create a "scrollable" layout in Android. Even using developers.android.com, though, I feel a little bit lost at the moment. I'm somewhat new to Java, but not so much that I feel I should be having these issues--being new to Android is the bigger problem right now. The layout I'm trying to create should scroll in a sort of a "grid". I THINK what I'm looking for is the Gallery view, but I'm really lost as to how to implement it at the moment. I want it to "snap" to center the frame, like in the actual Gallery application. Essentially, if I had a photo gallery of 9 pictures, the idea is to scroll between them up/down AND side to side, in a 3x3 manner. Doesn't need to dynamically adjust, or anything like that, I just want a grid I can scroll through. I'm also not asking for anyone to give me explicit code for it--I'm trying to learn, more than anything. But pointing me in the right direction for helpful layout programming resources would be greatly appreciated, and confirming if it's a Gallery view I'm looking for would also be really helpful. Thanks in advance.

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• Programming Environment for a Motorola 68000 in Linux

  - by Nick Presta

  Greetings all, I am taking a Structure and Application of Microcomputers course this semester and we're programming with the Motorola 68000 series CPU/board. The course syllabus suggests running something like Easy68K or Teesside Motorola 68000 Assembler/Emulator at home to test our programs. I told my prof I run x64 Linux and asked what sort of environment I would need to complete my coursework. He said that the easiest environment to use is a Windows XP 32bit VM with one of the two suggested applications installed, however, he doesn't really care what I use as long as I can test what I write at home. So I'm asking if there exists some sort of emulator or environment for Linux so I can test my code, and what sort of caveats I will run into by writing and testing my code in Linux. Also, I plan to do my editing in Vim, which probably isn't a problem, but I would like any insight into editors for 68000 assembly, if you have any. Thanks! EDIT: Just to clarify - I don't want to install Linux on the board at all - I want to program on my home machine, test the code locally, and then bring it onto the board for grading/running.

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• Managing libraries and imports in a programming language

  - by sub

  I've created an interpreter for a stupid programming language in C++ and the whole core structure is finished (Tokenizer, Parser, Interpreter including Symbol tables, core functions, etc.). Now I have a problem with creating and managing the function libraries for this interpreter (I'll explain what I mean with that later) So currently my core function handler is horrible: // Simplified version myLangResult SystemFunction( name, argc, argv ) { if ( name == "print" ) { if( argc < 1 ) { Error('blah'); } cout << argv[ 0 ]; } else if ( name == "input" ) { if( argc < 1 ) { Error('blah'); } string res; getline( cin, res ); SetVariable( argv[ 0 ], res ); } else if ( name == "exit ) { exit( 0 ); } And now think of each else if being 10 times more complicated and there being 25 more system functions. Unmaintainable, feels horrible, is horrible. So I thought: How to create some sort of libraries that contain all the functions and if they are imported initialize themselves and add their functions to the symbol table of the running interpreter. However this is the point where I don't really know how to go on. What I wanted to achieve is that there is e.g.: an (extern?) string library for my language, e.g.: string, and it is imported from within a program in that language, example: import string myString = "abcde" print string.at( myString, 2 ) # output: c My problems: How to separate the function libs from the core interpreter and load them? How to get all their functions into a list and add it to the symbol table when needed? What I was thinking to do: At the start of the interpreter, as all libraries are compiled with it, every single function calls something like RegisterFunction( string namespace, myLangResult (*functionPtr) ); which adds itself to a list. When import X is then called from within the language, the list built with RegisterFunction is then added to the symbol table. Disadvantages that spring to mind: All libraries are directly in the interpreter core, size grows and it will definitely slow it down.

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• Solving quadratic programming using R

  - by user702846

  I would like to solve the following quadratic programming equation using ipop function from kernlab : min 0.5*x'*H*x + f'*x subject to: A*x <= b Aeq*x = beq LB <= x <= UB where in our example H 3x3 matrix, f is 3x1, A is 2x3, b is 2x1, LB and UB are both 3x1. edit 1 My R code is : library(kernlab) H <- rbind(c(1,0,0),c(0,1,0),c(0,0,1)) f = rbind(0,0,0) A = rbind(c(1,1,1), c(-1,-1,-1)) b = rbind(4.26, -1.73) LB = rbind(0,0,0) UB = rbind(100,100,100) > ipop(f,H,A,b,LB,UB,0) Error in crossprod(r, q) : non-conformable arguments I know from matlab that is something like this : H = eye(3); f = [0,0,0]; nsamples=3; eps = (sqrt(nsamples)-1)/sqrt(nsamples); A=ones(1,nsamples); A(2,:)=-ones(1,nsamples); b=[nsamples*(eps+1); nsamples*(eps-1)]; Aeq = []; beq = []; LB = zeros(nsamples,1); UB = ones(nsamples,1).*1000; [beta,FVAL,EXITFLAG] = quadprog(H,f,A,b,Aeq,beq,LB,UB); and the answer is a vector of 3x1 equals to [0.57,0.57,0.57]; However when I try it on R, using ipop function from kernlab library ipop(f,H,A,b,LB,UB,0)) and I am facing Error in crossprod(r, q) : non-conformable arguments I appreciate any comment

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• Safe way for getting/finding a vertex in a graph with custom properties -> good programming practice

  - by Shadow

  Hi, I am writing a Graph-class using boost-graph-library. I use custom vertex and edge properties and a map to store/find the vertices/edges for a given property. I'm satisfied with how it works, so far. However, I have a small problem, where I'm not sure how to solve it "nicely". The class provides a method Vertex getVertex(Vertexproperties v_prop) and a method bool hasVertex(Vertexproperties v_prop) The question now is, would you judge this as good programming practice in C++? My opinion is, that I have first to check if something is available before I can get it. So, before getting a vertex with a desired property, one has to check if hasVertex() would return true for those properties. However, I would like to make getVertex() a bit more robust. ATM it will segfault when one would directly call getVertex() without prior checking if the graph has a corresponding vertex. A first idea was to return a NULL-pointer or a pointer that points past the last stored vertex. For the latter, I haven't found out how to do this. But even with this "robust" version, one would have to check for correctness after getting a vertex or one would also run into a SegFault when dereferencing that vertex-pointer for example. Therefore I am wondering if it is "ok" to let getVertex() SegFault if one does not check for availability beforehand?

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• Planning a programming project by example (C# or C++)

  - by Lunan

  I am in the last year of undergraduate degree and i am stumped by the lack of example in c++ and c# large project in my university. All the mini project and assignment are based on text based database, which is so inefficient, and console display and command, which is frustrating. I want to develop a complete prototype of corporate software which deals in Inventory, Sales, Marketing, etc. Everything you would usually find in SAP. I am grateful if any of you could direct me to a books or article or sample program. Some of the question are : How to plan for this kind of programming? should i use the concept of 1 object(such as inventory) have its own process and program and have an integrator sit for all the program, or should i integrate it in 1 big program? How to build and address a database? i have little bit knowledge in database and i know SQL but i never address database in a program before. Database are table, and how do you suppose to represent a table in a OOP way? For development type, which is better PHP and C++ or C# and ASP.NET? I am planning to use Web Interface to set form and information, but using a background program to handle the compute. .NET is very much integrated and coding should be much faster, but i really wonder about performance if compared to PHP and C++ package thank you for the info

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• Programming Practice

  - by deepti

  public DataTable UserUpdateTempSettings(int install_id, int install_map_id, string Setting_value,string LogFile) { SqlConnection oConnection = new SqlConnection(sConnectionString); DataSet oDataset = new DataSet(); DataTable oDatatable = new DataTable(); SqlDataAdapter MyDataAdapter = new SqlDataAdapter(); try { oConnection.Open(); cmd = new SqlCommand("SP_HOTDOC_PRINTTEMPLATE_PERMISSION", oConnection); cmd.Parameters.Add(new SqlParameter ("@INSTALL_ID", install_id)); cmd.Parameters.Add(new SqlParameter ("@INSTALL_MAP_ID", install_map_id)); cmd.Parameters.Add(new SqlParameter("@SETTING_VALUE", Setting_value)); if (LogFile != "") { cmd.Parameters.Add(new SqlParameter("@LOGFILE",LogFile)); } cmd.CommandType = CommandType.StoredProcedure; MyDataAdapter.SelectCommand = cmd; cmd.ExecuteNonQuery(); MyDataAdapter.Fill(oDataset); oDatatable = oDataset.Tables[0]; return oDatatable; } catch (Exception ex) { Utils.ShowError(ex.Message); return oDatatable; } finally { if ((oConnection.State != ConnectionState.Closed) || (oConnection.State != ConnectionState.Broken)) { oConnection.Close(); } oDataset = null; oDatatable = null; oConnection.Dispose(); oConnection = null; } } i have used execute non query.. normally its not used with data adapter... if iam not using its giving me error.. is it bad programming practice to use execute non query with data adapter

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