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• Advice for Architecture Design Logic for software application

  - by Prasad

  Hi, I have a framework of basic to complex set of objects/classes (C++) running into around 500. With some rules and regulations - all these objects can communicate with each other and hence can cover most of the common queries in the domain. My Dream: I want to provide these objects as icons/glyphs (as I learnt recently) on a workspace. All these objects can be dragged/dropped into the workspace. They have to communicate only through their methods(interface) and in addition to few iterative and conditional statements. All these objects are arranged finally to execute a protocol/workflow/dataflow/process. After drawing the flow, the user clicks the Execute/run button. All the user interaction should be multi-touch enabled. The best way to show my dream is : Jeff Han's Multitouch Video. consider Jeff is playing with my objects instead of the google maps. :-) it should be like playing a jigsaw puzzle. Objective: how can I achieve the following while working on this final product: a) the development should be flexible to enable provision for web services b) the development should enable easy web application development c) The development should enable client-server architecture - d) further it should also enable mouse based drag/drop desktop application like Adobe programs etc. I mean to say: I want to economize on investments. Now I list my efforts till now in design : a) Created an Editor (VB) where the user writes (manually) the object / class code b) On Run/Execute, the code is copied into a main() function and passed to interpreter. c) Catch the output and show it in the console. The interpreter can be separated to become a server and the Editor can become the client. This needs lot of standard client-server architecture work. But some how I am not comfortable in the tightness of this system. Without interpreter is there much faster and better embeddable solution to this? - other than writing a special compiler for these objects. Recently learned about AXIS-C++ can help me - looks like - a friend suggested. Is that the way to go ? Here are my questions: (pl. consider me a self taught programmer and NOT my domain) a) From the stage of C++ objects to multi-touch product, how can I make sure I will develop the parallel product/service models as well.? What should be architecture aspects I should consider ? b) What technologies are best suited for this? c) If I am thinking of moving to Cloud Computing, how difficult/ how redundant / how unnecessary my efforts will be ? d) How much time in months would it take to get the first beta ? I take the liberty to ask if any of the experts here are interested in this project, please email me: [email protected] Thank you for any help. Looking forward.

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• Performance Optimization for Matrix Rotation

  - by Summer_More_More_Tea

  Hello everyone: I'm now trapped by a performance optimization lab in the book "Computer System from a Programmer's Perspective" described as following: In a N*N matrix M, where N is multiple of 32, the rotate operation can be represented as: Transpose: interchange elements M(i,j) and M(j,i) Exchange rows: Row i is exchanged with row N-1-i A example for matrix rotation(N is 3 instead of 32 for simplicity): ------- ------- |1|2|3| |3|6|9| ------- ------- |4|5|6| after rotate is |2|5|8| ------- ------- |7|8|9| |1|4|7| ------- ------- A naive implementation is: #define RIDX(i,j,n) ((i)*(n)+(j)) void naive_rotate(int dim, pixel *src, pixel *dst) { int i, j; for (i = 0; i < dim; i++) for (j = 0; j < dim; j++) dst[RIDX(dim-1-j, i, dim)] = src[RIDX(i, j, dim)]; } I come up with an idea by inner-loop-unroll. The result is: Code Version Speed Up original 1x unrolled by 2 1.33x unrolled by 4 1.33x unrolled by 8 1.55x unrolled by 16 1.67x unrolled by 32 1.61x I also get a code snippet from pastebin.com that seems can solve this problem: void rotate(int dim, pixel *src, pixel *dst) { int stride = 32; int count = dim >> 5; src += dim - 1; int a1 = count; do { int a2 = dim; do { int a3 = stride; do { *dst++ = *src; src += dim; } while(--a3); src -= dim * stride + 1; dst += dim - stride; } while(--a2); src += dim * (stride + 1); dst -= dim * dim - stride; } while(--a1); } After carefully read the code, I think main idea of this solution is treat 32 rows as a data zone, and perform the rotating operation respectively. Speed up of this version is 1.85x, overwhelming all the loop-unroll version. Here are the questions: In the inner-loop-unroll version, why does increment slow down if the unrolling factor increase, especially change the unrolling factor from 8 to 16, which does not effect the same when switch from 4 to 8? Does the result have some relationship with depth of the CPU pipeline? If the answer is yes, could the degrade of increment reflect pipeline length? What is the probable reason for the optimization of data-zone version? It seems that there is no too much essential difference from the original naive version. EDIT: My test environment is Intel Centrino Duo processor and the verion of gcc is 4.4 Any advice will be highly appreciated! Kind regards!

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• How to set a key binding to make Emacs as transparent/opaque as I want?

  - by Vivi

  I want to have a command in Emacs to make it as opaque/transparent as I want (refer to the fabulous question that pointed out that transparency is possible in Emacs, and the EmacsWiki page linked there which has the code I am using below). The EmacsWiki code sets "C-c t" to toggle the previously set transparency on and off: ;;(set-frame-parameter (selected-frame) 'alpha '(<active> [<inactive>])) (set-frame-parameter (selected-frame) 'alpha '(85 50)) (add-to-list 'default-frame-alist '(alpha 85 50)) enter code here(eval-when-compile (require 'cl)) (defun toggle-transparency () (interactive) (if (/= (cadr (find 'alpha (frame-parameters nil) :key #'car)) 100) (set-frame-parameter nil 'alpha '(100 100)) (set-frame-parameter nil 'alpha '(85 60)))) (global-set-key (kbd "C-c t") 'toggle-transparency) What I would like to do is to be able to choose the % transparency when I am in Emacs. If possible, I would like a command where I type for example "C-c t N" (where N is the % opaqueness) for the active frame, and then "M-c t N" for the inactive window. If that can't be done like that, then maybe a command where if I type "C-c t" it asks me for the number which gives the opaqueness of the active window (and the same for the inactive window using "M-c t"). Thanks in advance for your time :) Below are just some comments that are not important to answer the question if you are not interested: I really want this because when I told my supervisor I was learning Emacs he said TexShop is much better and that I am using software from the 80's. I told him about the wonders of Emacs and he said TexShop has all of it and more. I matched everything he showed me except for the transparency (though he couldn't match the preview inside Emacs from preview-latex). I found the transparency thing by chance, and now I want to show him Emacs rules! I imagine this will be a piece of cake for some of you, and even though I could get it done if I spent enough time trying to learn lisp or reading around, I am not a programmer and I have only been using Emacs and a mac for a week. I am lost already as it is! So thanks in advance for your time and help - I will learn lisp eventually!

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• Creating a spam list with a web crawler in python

  - by user313623

  Hey guys, I'm not trying to do anything malicious here, I just need to do some homework. I'm a fairly new programmer, I'm using python 3.0, and I having difficulty using recursion for problem-solving. I've been stuck on this question for quite a while. Here's the assignment: Write a recursive method spam(url, n) that takes a url of a web page as input and a non-negative integer n, collects all the email address contained in the web page and adds them to a global dictionary variable spam_dict, and then recursively calls itself on every http hyperlink contained in the web page. You will use a dictionary so only one copy of every email address is save; your dictionary will store (key,value) pairs (email, email). The recursive call should use the parameter n-1 instead of n. If n = 0, you should collect the email addresses but no recursive calls should be made. The parameter n is used to limit the recursion to at most depth n. You will need to use the solutions of the two above problems; you method spam() will call the methods links2() and emails() and possibly other functions as well. Notes: 1. running spam() directly will produce no output on the screen; to find your spam_dict, you will need to read the value of spam_dict, and you will also need to reset it to the empty dictionary before every run of spam. 2. Recall how global variables are used. Usage: spam_dict = {} spam('http://reed.cs.depaul.edu/lperkovic/csc242/test1.html',0) spam_dict.keys() dict_keys([]) spam_dict = {} spam('http://reed.cs.depaul.edu/lperkovic/csc242/test1.html',1) spam_dict.keys() dict_keys(['[email protected]', '[email protected]']) So far, I've written a function that traverses web pages and puts all the links in a nice little list, and what I wanted to do was call that functions. And why would I use recursion on a dictionary? And how? I don't understand how n ties into all of this. def links2(url): content = str(urlopen(url).read()) myparser = MyHTMLParser() myparser.feed(content) lst = myparser.get() mergelst = [] for link in lst: mergelst.append(urljoin(lst[0],link)) print(mergelst) Any input (except why spam is bad) would be greatly appreciated. Also, I realize that the above function could probably look better, if you have a way to do it, I'm all ears. However, all I need is the point is for the program to produce the proper output.

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• random, Graphics point ,searching- algorithm, via dual for loop set

  - by LoneXcoder

  hello and thanks for joining me in my journey to the custom made algorithm for "guess where the pixel is" this for Loop set (over Point.X, Point.Y), is formed in consecutive/linear form: //Original\initial Location Point initPoint = new Point(150, 100); // No' of pixels to search left off X , and above Y int preXsrchDepth, preYsrchDepth; // No' of pixels to search to the right of X, And Above Y int postXsrchDepth, postYsrchDepth; preXsrchDepth = 10; // will start search at 10 pixels to the left from original X preYsrchDepth = 10; // will start search at 10 pixels above the original Y postXsrchDepth = 10; // will stop search at 10 pixels to the right from X postYsrchDepth = 10; // will stop search at 10 pixels below Y int StopXsearch = initPoint.X + postXsrchDepth; //stops X Loop itarations at initial pointX + depth requested to serch right of it int StopYsearch = initPoint.Y + postYsrchDepth; //stops Y Loop itarations at initial pointY + depth requested below original location int CountDownX, CountDownY; // Optional not requierd for loop but will reports the count down how many iterations left (unless break; triggerd ..uppon success) Point SearchFromPoint = Point.Empty; //the point will be used for (int StartX = initPoint.X - preXsrchDepth; StartX < StopXsearch; StartX++) { SearchFromPoint.X = StartX; for (int StartY = initPoint.Y - preYsrchDepth; StartY < StpY; StartY++) { CountDownX = (initPoint.X - StartX); CountDownY=(initPoint.Y - StartY); SearchFromPoint.Y = StartY; if (SearchSuccess) { same = true; AAdToAppLog("Search Report For: " + imgName + "Search Completed Successfully On Try " + CountDownX + ":" + CountDownY); break; } } } <-10 ---- -5--- -1 X +1--- +5---- +10 what i would like to do is try a way of instead is have a little more clever approach <+8---+5-- -8 -5 -- +2 +10 X -2 - -10 -8-- -6 ---1- -3 | +8 | -10 Y +1 -6 | | +9 .... I do know there's a wheel already invented in this field (even a full-trailer truck amount of wheels (: ) but as a new programmer, I really wanted to start of with a simple way and also related to my field of interest in my project. can anybody show an idea of his, he learnt along the way to Professionalism in algorithm /programming having tests to do on few approaches (kind'a random cleverness...) will absolutely make the day and perhaps help some others viewing this page in the future to come it will be much easier for me to understand if you could use as much as possible similar naming to variables i used or implenet your code example ...it will be Greatly appreciated if used with my code sample, unless my metod is a realy flavorless. p.s i think that(atleast as human being) the tricky part is when throwing inconsecutive numbers you loose track of what you didn't yet use, how do u take care of this too . thanks allot in advance looking forward to your participation !

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• Do you feel underappreciated or resent the geek/nerd stigma?

  - by dotnetdev

  At work we have a piece of A4 paper with the number of everyone in the office. The structure of this document is laid out in rectangles, by department. I work for the department that does all the technical stuff. That includes support—bear in mind that the support staff isn't educated in IT but just has experience in PC maintenance and providing support to a system we resell but don't have source code access to, project manager, team leader, a network administrator, a product manager, and me, a programmer. Anyway, on this paper, we are labelled as nerds and geeks. I did take a little offence to this, as much as it is light hearted (but annoying and old) humour. I have a vivid image that a geek is someone who doesn't go out but codes all day. I code all day at home and at work (when I have something to code...), but I keep balance by going out. I don't know why it is only people who work with computers that get such a stigma. No other profession really gets the same stigma—skilled, technical, or whatever. An account manager (and this is hardly a skilled job) says, "Perhaps [MY NAME HERE] could write some geeky code tomorrow to add this functionality to the website." It is funny how I get such an unfair stigma but I am so pivotal. In fact, if it wasn't for me, the company would have nothing to sell so the account managers would be redundant! I make systems, they get sold, and this is what pays the wages. It's funny how the account managers get a commission for how many systems they sell, or manage to make clients resubscribe to. Yet I built the thing in the first place! On top of that, my brother says all I do is type stuff on a keyboard all day. Surely if I did, I'd be typing at my normal typing speed of 100wpm+ as if I am writing a blog entry. Instead, I plan as I code along on the fly if commercial pressures and time prohibit proper planning. I never type as if I'm writing normal English. There is more to our jobs than just typing code. And my brother is a pipe fitter with no formal qualifications in his name. I could easily, and perhaps more justifiably, say he just manipulates a spanner or something. Does you feel underappreciated or that a geek/nerd stigma is undeserved or unfair?

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• Function Point Analysis -- a seriously over-estimating technique?

  - by kizzx2

  I know questions about FPA has been asked numerous times before, but this time I'm taking a more analytical angle at it, backed up with data. 1. First, some data This question is based on a tutorial. He had a "Sample Count" section where he demonstrated it step by step. You can see some screenshots of his sample application here. In the end, he calculated the unadjusted FP to be 99. There is another article on InformIT with industry data on typical hour/FP. It ranges from 2 hours/FP to 27.4 hours/FP. Let's try to stick with 2 for the moment (since SO readers are probably the more efficient crowd :p). 2. Reality check!? Now just check out the screenshots again. Do a little math here 99 * 2 = 198 hours 198 hours / 40 hours per week = 5 weeks Seriously? That sample application is going to take 5 weeks to implement? Is it just my feeling that it wouldn't take any decent programmer longer than one week to have it completed? Now let's try estimating the cost of the project. We'll use New York's minimum wage at the moment (Wikipedia), which is $7.25 198 * 7.25 = $1435.5 From what I could see from the screenshots, this application is a small excel-improvement app. I could have bought MS Office Pro for 200 bucks which gives me greater interoperability (.xls files) and flexibility (spreadsheets). (For the record, that same Web site has another article discussing productivity. It seems like they typically use 4.2 hours/FP, which gives us even more shocking stats: 99 * 4.2 = 415 hours = 10 weeks = almost 3 whopping months! 415 hours * $7.25 = $3000 zomg (That's even assuming that all our poor coders get the minimum wage!) 3. Am I missing something here? Right now, I could come up with several possible explanation: FPA is really only suited for bigger projects (1000+ FPs) so it becomes extremely inaccurate at smaller scale. The hours/FP metric fluctuates abruptly from team to team, project to project. For a small project like this, we could have used something like 0.5 hour/FP or something. (Now this kind of makes the whole estimation thing pointless, unless my firm does the same type of projects for several years with the same team, not really common.) From my experience with several software metrics, Function Point is really not a lightweight metric. If the hour/FP thing fluctuates so much, then what's the point, maybe I could have gone with User Story Points which is a lot faster to get and arguably almost as uncertain. What would be the FP experts' answers to this?

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• How do we, as a community, help encourage programming in public schools? (Or state Schools for the U

  - by NoMoreZealots

  PRIMARY MOTIVATION My office gets involved with the "First Robotics" competitions and one thing that lingers year to year is the students typically have no preparation for doing even simple programming as part of the public schools system. While the science classes provide some basic grasp of mechanical and electrical concepts, by in large computer programming gets no coverage from the curriculum. (This my be different in other areas of the country/world.) What makes it worse is there is only a short period of time you have to prepare the student's and help them design the robot. Talking to some professors from local colleges, it's a problem because you can't assume even the most basic understanding for freshman CS majors. Languages like Python, Lua and BASIC are simple enough for at least high school level students, if not younger. SCOPE So how do you get public schools to support a programming, at least to the level of "Try it in BASIC" examples that used to be at the end of a chapter in my Algebra book? At least enough to prepare them for event's such as the FIRST Robotic competitions. Which the primary objectives are to teach problem solving and team work, and to possible foster an interest in Math, Science and Engineering in general. (Not force feed to them, as some people her seem to be implying.) Edit: Why teach kids: (Since 2000 CS enrollment in US colleges has decreased by 70% while college enrollment has increased, this is a PROBLEM.) Saying there is no value in teaching someone programming in Jr./High school because they might think "they know programming." Is like saying there's no value in teaching High school science and physics, because they might decide they "know physics." Leading to abuse like: "I passed a high school physics class, I'm going to develop a Unified Quantum Gravitational Theory." Better Prepared students are better students. Instead it would allows college programs to raise the bar on the entry level courses, allowing students to be weeded out based on their understanding of more advanced material. Plus people who did poorly in that in topic in High school aren't as likely to say "I think there's money in computer's so I'll computer science." Plus if people take it in high school and decide THEN that it's not for them, it's better than them wasting their money to PAY a college to figure that out. The result is that people who take the degree are more likely to succeed and be there for the RIGHT reasons. (i.e. It's what they REALLY want to do. And that's REALLY the key to being good at anything.) Programming is like anything else, the more practice and genuine interest you have the better you get. If you start them later, they get less practice. The earlier give them the opportunity to start, the more practice they will get. All other things equal, the more practice the better the programmer.

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• Good working habits to observe in project development?

  - by Will Marcouiller

  As my development experience grows, I see fit to stick to best practices from here and there to build somehow my own working practices while observing the conventions, etc. I'm currently working on a project which my goals is to graduate the security access model from an environment's Active Directory to another environment's automatically. I don't know for any of you, but as far as I'm concerned, I meet some real difficulties sticking to only one way, then develop. I mean, I learn something new everyday while visiting SO, and recently wanted to get acquainted with generics. On the other hand, I better know the Façade pattern which proved to be very practical in transactional programming in process systems. This seems to be less practical for desktop application as there are plenty of variables to consider in a desktop application that you don't have to care in transactional programming, as you're playing only with information data. As for my current project, I have: Groups; Organizational Units; Users. Which are all considered an entry in the Active Directory. This points out to be a good candidate for generics, as also approached this way by Bart de Smett's Linq to AD on CodePlex. He has a DirectorySource<T>, and to manage let's say groups, then he instantiate a source with the proper type: var groups = new DirectorySource<Group>(); This seems to be very a good way of doing. Despite, I seem to go from one pattern to another and I don't seem to be able to strictly stick to one. While I'm aware that one must not stay with only one way of doing, since each pattern statisfies certain advantages, while also illustrating disadvantages under some usage conditions, I seem to want to develop with both patterns having a singleton Façade class with the underlying factories which represent the sub systems: GroupsFactory; UsersFactory; OrganizationalUnitsFactory. Each of the factories offers the possible operations for their respective entity (group, user, OU). To make a very long story short, I often have plenty of ideas while developping and this causes me some trouble, as I go from an idea to another feeling completely lost after a while. Yet I understand the advantages and disavantages, I have no trouble choosing from one pattern to another depending on the situation. Nevertheless, when it comes to programming itself, if I'm not part of a team, I feel sometimes like I can't do anything good. That is, because I can't stand not doing something "perfect" the first time. The role I play within the project is both: the project manager and the programmer. I am more comfortable in the project manager role, architectural role, analytical role than the developer's. Has any of you some good habbits to observe in project development? Thanks to you all! =)

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• Multiple infowindows - tearing my hair out

  - by thewinchester

  Ok, I'll admit I'm nowhere near the best programmer on the planet - and I'm used to the answer staring me right in the face but not making sense of it. Problem I need to display multiple markers on a map, each with their own infowindow. I have created the individual markers without a problem, but don't know how to create the infowindows for each. Steps so far I am generating a map using the V3 API within an ASP-based website, with markers being created from a set of DB records. The markers are created by looping through a rs and defining a marker() with the relevant variables: var myLatlng = new google.maps.LatLng(lat,long); var marker = new google.maps.Marker({ map: map, position: myLatlng, title: 'locationname', icon: 'http://google-maps-icons.googlecode.com/files/park.png' }); This is creating all the relevant markers in their correct locations. What I need to do now, and am not sure of how to achieve is give each of them their own unique infowindow which I can use to display information and links relevant to that marker. Source <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script> <script language="javascript"> $(document).ready(function() { //Google Maps var myOptions = { zoom: 5, center: new google.maps.LatLng(-26.66, 122.25), mapTypeControl: false, mapTypeId: google.maps.MapTypeId.ROADMAP, navigationControl: true, navigationControlOptions: { style: google.maps.NavigationControlStyle.SMALL } } var map = new google.maps.Map(document.getElementById("map_canvas"), myOptions); <!-- While locations_haslatlong not BOF.EOF --> <% While ((Repeat1__numRows <> 0) AND (NOT locations_haslatlong.EOF)) %> var myLatlng = new google.maps.LatLng(<%=(locations_haslatlong.Fields.Item("llat").Value)%>,<%=(locations_haslatlong.Fields.Item("llong").Value)%>); var marker = new google.maps.Marker({ map: map, position: myLatlng, title: '<%=(locations_haslatlong.Fields.Item("ldescription").Value)%>', icon: 'http://google-maps-icons.googlecode.com/files/park.png', clickable: true, }); <% Repeat1__index=Repeat1__index+1 Repeat1__numRows=Repeat1__numRows-1 locations_haslatlong.MoveNext() Wend %> <!-- End While locations_haslatlong not BOF.EOF --> google.maps.event.addListener(marker, 'click', function() { infowindow.open(map,marker); }); google.maps.event.addListener(marker, 'dblclick', function() { map.setZoom(14); }); });

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• Autocomplete server-side implementation

  - by toluju

  What is a fast and efficient way to implement the server-side component for an autocomplete feature in an html input box? I am writing a service to autocomplete user queries in our web interface's main search box, and the completions are displayed in an ajax-powered dropdown. The data we are running queries against is simply a large table of concepts our system knows about, which matches roughly with the set of wikipedia page titles. For this service obviously speed is of utmost importance, as responsiveness of the web page is important to the user experience. The current implementation simply loads all concepts into memory in a sorted set, and performs a simple log(n) lookup on a user keystroke. The tailset is then used to provide additional matches beyond the closest match. The problem with this solution is that it does not scale. It currently is running up against the VM heap space limit (I've set -Xmx2g, which is about the most we can push on our 32 bit machines), and this prevents us from expanding our concept table or adding more functionality. Switching to 64-bit VMs on machines with more memory isn't an immediate option. I've been hesitant to start working on a disk-based solution as I am concerned that disk seek time will kill performance. Are there possible solutions that will let me scale better, either entirely in memory or with some fast disk-backed implementations? Edits: @Gandalf: For our use case it is important the the autocompletion is comprehensive and isn't just extra help for the user. As for what we are completing, it is a list of concept-type pairs. For example, possible entries are [("Microsoft", "Software Company"), ("Jeff Atwood", "Programmer"), ("StackOverflow.com", "Website")]. We are using Lucene for the full search once a user selects an item from the autocomplete list, but I am not yet sure Lucene would work well for the autocomplete itself. @Glen: No databases are being used here. When I'm talking about a table I just mean the structured representation of my data. @Jason Day: My original implementation to this problem was to use a Trie, but the memory bloat with that was actually worse than the sorted set due to needing a large number of object references. I'll read on the ternary search trees to see if it could be of use.

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• Recommended textbook for machine-level programming?

  - by Norman Ramsey

  I'm looking at textbooks for an undergraduate course in machine-level programming. If the perfect book existed, this is what it would look like: Uses examples written in C or assembly language, or both. Covers machine-level operations such as two's-complement integer arithmetic, bitwise operations, and floating-point arithmetic. Explains how caches work and how they affect performance. Explains machine instructions or assembly instructions. Bonus if the example assembly language includes x86; triple bonus if it includes x86-64 (aka AMD64). Explains how C values and data structures are represented using hardware registers and memory. Explains how C control structures are translated into assembly language using conditional and unconditional branch instructions. Explains something about procedure calling conventions and how procedure calls are implemented at the machine level. Books I might be interested in would probably have the words "machine organization" or "computer architecture" in the title. Here are some books I'm considering but am not quite happy with: Computer Systems: A Programmer's Perspective by Randy Bryant and Dave O'Hallaron. This is quite a nice book, but it's a book for a broad, shallow course in systems programming, and it contains a great deal of material my students don't need. Also, it is just out in a second edition, which will make it expensive. Computer Organization and Design: The Hardware/Software Interface by Dave Patterson and John Hennessy. This is also a very nice book, but it contains way more information about how the hardware works than my students need. Also, the exercises look boring. Finally, it has a show-stopping bug: it is based very heavily on MIPS hardware and the use of a MIPS simulator. My students need to learn how to use DDD, and I can't see getting this to work on a simulator. Not to mention that I can't see them cross-compiling their code for the simulator, and so on and so forth. Another flaw is that the book mentions the x86 architecture only to sneer at it. I am entirely sympathetic to this point of view, but news flash! You guys lost! Write Great Code Vol I: Understanding the Machine by Randall Hyde. I haven't evaluated this book as thoroughly as the other two. It has a lot of what I need, but the translation from high-level language to assembler is deferred to Volume Two, which has mixed reviews. My students will be annoyed if I make them buy a two-volume series, even if the price of those two volumes is smaller than the price of other books. I would really welcome other suggestions of books that would help students in a class where they are to learn how C-language data structures and code are translated to machine-level data structures and code and where they learn how to think about performance, with an emphasis on the cache.

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• Function Point Analysis -- a seriously overestimating technique?

  - by kizzx2

  I know questions about FPA has been asked numerous times before, but this time I'm taking a more analytical angle at it, backed up with data. 1. First, some data This question is based on a tutorial. He had a "Sample Count" section where he demonstrated it step by step. You can see some screenshots of his sample application here. In the end, he calculated the unadjusted FP to be 99. There is another article on InformIT with industry data on typical hour/FP. It ranges from 2 hours/FP to 27.4 hours/FP. Let's try to stick with 2 for the moment (since SO readers are probably the more efficient crowd :p). 2. Reality check!? Now just check out the screenshots again. Do a little math here 99 * 2 = 198 hours 198 hours / 40 hours per week = 5 weeks Seriously? That sample application is going to take 5 weeks to implement? Is it just my feeling that it wouldn't take any decent programmer longer than one week (I"m not even saying weekend) to have it completed? Now let's try estimating the cost of the project. We'll use New York's minimum wage at the moment (Wikipedia), which is $7.25 198 * 7.25 = $1435.5 From what I could see from the screenshots, this application is a small excel-improvement app. I could have bought MS Office Pro for 200 bucks which gives me greater interoperability (.xls files) and flexibility (spreadsheets). (For the record, that same Web site has another article discussing productivity. It seems like they typically use 4.2 hours/FP, which gives us even more shocking stats: 99 * 4.2 = 415 hours = 10 weeks = almost 3 whopping months! 415 hours * $7.25 = $3000 zomg (That's even assuming that all our poor coders get the minimum wage!) 3. Am I missing something here? Right now, I could come up with several possible explanation: FPA is really only suited for bigger projects (1000+ FPs) so it becomes extremely inaccurate at smaller scale. The hours/FP metric fluctuates abruptly from team to team, project to project. For a small project like this, we could have used something like 0.5 hour/FP or something. (Now this kind of makes the whole estimation thing pointless, unless my firm does the same type of projects for several years with the same team, not really common.) From my experience with several software metrics, Function Point is really not a lightweight metric. If the hour/FP thing fluctuates so much, then what's the point, maybe I could have gone with User Story Points which is a lot faster to get and arguably almost as uncertain. What would be the FP experts' answers to this?

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• USB windows xp final USB access issues

  - by Lex Dean

  I basically understand you C++ people, Please do not get distracted because I'm writing in Delphi. I have a stable USB Listing method that accesses all my USB devices I get the devicepath, and this structure: TSPDevInfoData = packed record Size: DWORD; ClassGuid: TGUID; DevInst: DWORD; // DEVINST handle Reserved: DWord; end; I get my ProductID and VenderID successfully from my DevicePath Lists all USB devices connected to the computer at the time That enables me to access the registry data to each device in a stable way. What I'm lacking is a little direction Is friendly name able to be written inside the connected USB Micro chips by the firmware programmer? (I'm thinking of this to identify the device even further, or is this to help identify Bulk data transfer devices like memory sticks and camera's) Can I use SPDRP_REMOVAL_POLICY_OVERRIDE to some how reset these polices What else can I do with the registry details. Identifying when some one unplugs a device The program is using (in windows XP standard) I used a documented windows event that did not respond. Can I read a registry value to identify if its still connected? using CreateFileA (DevicePath) to send and receive data I have read when some one unplugs in the middle of a data transfer its difficult clearing resources. what can IoCreateDevice do for me and how does one use it for that task This two way point of connection status and system lock up situations is very concerning. Has some one read anything about this subject recently? My objectives are to 1. list connected USB devices identify a in development Micro Controller from everything else send and receive data in a stable and fast way to the limits of the controller No lock up's transferring data Note I'm not using any service packs I understand everything USB is in ANSI when windows xp is not and .Net is all about ANSI (what a waste of memory) I plan to continue this project into a .net at a later date as an addition. MSDN gives me Structures and Functions and what should link to what ok but say little to what they get used for. What is available in my language Delphi is way over priced that it needs a major price drop.

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• Matching array elements to get an array element at another index

  - by bccarlso

  I have a PHP array that I'm using to generate an HTML form. The PHP array is this: <?php $vdb = array ( array( "Alabama", 275), array( "Alaska", 197), array( "Arizona", 3322)); ?> The PHP to generate the HTML form is below. I need to have the value be the name of the state, because there is some AJAX I'm using to display which states a user has chosen. <?php echo "<table border='1'><thead><tr><th></th><th>State</th><th>Contacts</th><th>Email</th></tr></thead>"; for ($row = 0; $row < 42; $row++) { echo "<tr><td class='input_button'><input type='checkbox' name='vdb[]' value='".$vdb[$row][0]."' title='".$vdb[$row][1]."' /></td>"; echo "<td>".$vdb[$row][0]."</td>"; echo "<td>".$vdb[$row][1]."</td>"; } echo "</table>"; ?> What I'm trying to do is, on submission of the form, with the states the user selected, loop through the PHP array and total the numbers from the selected states. So if I checked Alabama and Alaska, I'd want to add 275 + 197. This is what I thought would have worked, but it's not: <?php $vendors = array(); if (isset($_POST["vdb"])) { $vendors = $_POST["vdb"]; } $ven_i = 0; $ven_j = 0; $ven_total = 0; foreach ($vendors as $value) { foreach ($vdb as $vdb_value) { if ($vendors[$ven_i] == $vdb[$ven_j][0]) { $ven_total += $vdb[$ven_j][1]; } $ven_j++; } $ven_i++; } ?> and then $ven_total should be the total I'm looking for. However, $ven_total just ends up being the first checkbox selected, and it ignores the rest. I am doing this correctly with the AJAX, displaying the total on the front end, but I don't know how to pass that on to the form submission. I'd rather not using GET and URL variables, because a user could type something into the URL and modify the count. Any idea what I'm doing wrong, or a better way to approach this that I would be able to understand? (Very much a novice programmer.)

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• help Implementing Object Oriented ansi-C approach??

  - by No Money

  Hey there, I am an Intermediate programmer in Java and know some of the basics in C++. I recently started to scam over "C language" [please note that i emphasized on C language and want to stick with C as i found it to be a perfect tool, so no need for suggestions focusing on why should i move back to C++ or Java]. Moving on, I code an Object Oriented approach in C but kindda scramble with the pointers part. Please understand that I am just a noob trying to extend my knowledge beyond what i learned in High School. Here is my code..... #include <stdio.h> typedef struct per{ int privateint; char *privateString; struct per (*New) (); void (*deleteperOBJ) (struct t_person *); void (*setperNumber) ((struct*) t_person,int); void (*setperString) ((struct*) t_person,char *); void (*dumpperState) ((struct*) t_person); }t_person; void setperNumber(t_person *const per,int num){ if(per==NULL) return; per->privateint=num; } void setperString(t_person *const per,char *string){ if(per==NULL) return; per->privateString=string; } void dumpperState(t_person *const per){ if(per==NULL) return; printf("value of private int==%d\n", per->privateint); printf("value of private string==%s\n", per->privateString); } void deleteperOBJ(struct t_person *const per){ free((void*)t_person->per); t_person ->per = NULL; } main(){ t_person *const per = (struct*) malloc(sizeof(t_person)); per = t_person -> struct per -> New(); per -> setperNumber (t_person *per, 123); per -> setperString(t_person *per, "No money"); dumpperState(t_person *per); deleteperOBJ(t_person *per); } Just to warn you, this program has several errors and since I am a beginner I couldn't help except to post this thread as a question. I am looking forward for assistance. Thanks in advance.

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• How to check for palindrome using Python logic

  - by DrOnline

  My background is only a 6 month college class in basic C/C++, and I'm trying to convert to Python. I may be talking nonsense, but it seems to me C, at least at my level, is very for-loop intensive. I solve most problems with these loops. And it seems to me the biggest mistake people do when going from C to Python is trying to implement C logic using Python, which makes things run slowly, and it's just not making the most of the language. I see on this website: http://hyperpolyglot.org/scripting (serach for "c-style for", that Python doesn't have C-style for loops. Might be outdated, but I interpret it to mean Python has its own methods for this. I've tried looking around, I can't find much up to date (Python 3) advice for this. How can I solve a palindrome challenge in Python, without using the for loop? I've done this in C in class, but I want to do it in Python, on a personal basis. The problem is from the Euler Project, great site btw. def isPalindrome(n): lst = [int(n) for n in str(n)] l=len(lst) if l==0 || l==1: return True elif len(lst)%2==0: for k in range (l) ##### else: while (k<=((l-1)/2)): if (list[]): ##### for i in range (999, 100, -1): for j in range (999,100, -1): if isPalindrome(i*j): print(i*j) break I'm missing a lot of code here. The five hashes are just reminders for myself. Concrete questions: 1) In C, I would make a for loop comparing index 0 to index max, and then index 0+1 with max-1, until something something. How to best do this in Python? 2) My for loop (in in range (999, 100, -1), is this a bad way to do it in Python? 3) Does anybody have any good advice, or good websites or resources for people in my position? I'm not a programmer, I don't aspire to be one, I just want to learn enough so that when I write my bachelor's degree thesis (electrical engineering), I don't have to simultaneously LEARN an applicable programming language while trying to obtain good results in the project. "How to go from basic C to great application of Python", that sort of thing. 4) Any specific bits of code to make a great solution to this problem would also be appreciated, I need to learn good algorithms.. I am envisioning 3 situations. If the value is zero or single digit, if it is of odd length, and if it is of even length. I was planning to write for loops... PS: The problem is: Find the highest value product of two 3 digit integers that is also a palindrome.

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• Need a fast programming language that can drive two printers

  - by Pete

  I have a rather unusual application that isn't working the way I need, and I hope someone here will have some suggestions or at least a direction to investigate. We have a museum exhibit that has a computer at the entrance driving two small receipt printers. There are two buttons on a console, wired to the left and right buttons of a disemboweled mouse. The two printers and associated buttons are for girls and boys, each button does a random selection from a database of names and prints a small ticket on the appropriate printer with a graphic image, a few words about the exhibit and the randomly chosen name. Conceptually all is well, but it hangs quite often. I got the project at the last minute, because the original designer got bogged down and couldn't deliver, so the exhibit's author asked me the day before opening, whether I could write something that would work. I did it in Word, since I am an experienced VBA programmer. Several other avenues I attempted first all lead to dead ends - one couldn't do graphics, another couldn't handle two printers, yet another couldn't change fonts and so on. The problem is that it simply isn't fast enough - Word can only drive one printer at a time and changing the active printer takes a long time. Not by office standards, where a second or two of delay before a printer starts working on your document is not an issue, but here I need more or less instant response. If kids press a button and nothing happens, they press it over and over until something does happen, resulting in maybe half a dozen commands being sent before the printer starts reacting. Sometimes it jams the program completely, since boys and girls will be pressing the two buttons simultaneously and Word locks up, and even when it doesn't jam, the printers then spit out a stream of tickets, making a mess. The kids start squabbling over which ticket is whose, pulling them out of the printers, snarling the paper tape, jamming the printer and generally making a mess of the whole affair, often necessitating the exhibit caretakers having to restart the computer and clear torn bits of paper out the printers. What I need is some sort of fast programming language that can drive two printers *-simultaneously-*, not the MSOffice claptrap of having to switch the active printer, that can react to both left and right mouse button click events, can print a small graphic image and can print in different font sizes and styles and. I don't need many, but it's not all in one typeface. Can anyone suggest what I might use for this? I don't even know if it's possible at all under Windows, whether the "single active printer" garbage is an Office artifact, or a Windows restriction. My little Commodore-64 twenty-five years ago had two printers attached to it and drove both simultaneously with no difficulties - it doesn't seem to me it should be such an impossible requirement today.

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• Do You Really Know Your Programming Languages?

  - by Kristopher Johnson

  I am often amazed at how little some of my colleagues know or care about their craft. Something that constantly frustrates me is that people don't want to learn any more than they need to about the programming languages they use every day. Many programmers seem content to learn some pidgin sub-dialect, and stick with that. If they see a keyword or construct that they aren't familiar with, they'll complain that the code is "tricky." What would you think of a civil engineer who shied away from calculus because it had "all those tricky math symbols?" I'm not suggesting that we all need to become "language lawyers." But if you make your living as a programmer, and claim to be a competent user of language X, then I think at a minimum you should know the following: Do you know the keywords of the language and what they do? What are the valid syntactic forms? How are memory, files, and other operating system resources managed? Where is the official language specification and library reference for the language? The last one is the one that really gets me. Many programmers seem to have no idea that there is a "specification" or "standard" for any particular language. I still talk to people who think that Microsoft invented C++, and that if a program doesn't compile under VC6, it's not a valid C++ program. Programmers these days have it easy when it comes to obtaining specs. Newer languages like C#, Java, Python, Ruby, etc. all have their documentation available for free from the vendors' web sites. Older languages and platforms often have standards controlled by standards bodies that demand payment for specs, but even that shouldn't be a deterrent: the C++ standard is available from ISO for $30 (and why am I the only person I know who has a copy?). Programming is hard enough even when you do know the language. If you don't, I don't see how you have a chance. What do the rest of you think? Am I right, or should we all be content with the typical level of programming language expertise? Update: Several great comments here. Thanks. A couple of people hit on something that I didn't think about: What really irks me is not the lack of knowledge, but the lack of curiosity and willingness to learn. It seems some people don't have any time to hone their craft, but they have plenty of time to write lots of bad code. And I don't expect people to be able to recite a list of keywords or EBNF expressions, but I do expect that when they see some code, they should have some inkling of what it does. Few people have complete knowledge of every dark corner of their language or platform, but everyone should at least know enough that when they see something unfamiliar, they will know how to get whatever additional information they need to understand it.

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• Chrome extension - Localstorage not working

  - by Bjarki Jonasson

  I'm writing a Chrome extension that uses a content script to modify certain parts of a website. The content script worked fine until I tried to add an options page to my extension. Right now I'm using an options.html file to save user preferences to localstorage, as you can see here: <html> <head><title>Options</title></head> <script type="text/javascript"> function save_options() { var select = document.getElementById("width"); var width = select.children[select.selectedIndex].value; localStorage["site_width"] = width; } function restore_options() { var fwidth = localStorage["site_width"]; if (!fwidth) { return; } var select = document.getElementById("width"); for (var i = 0; i < select.children.length; i++) { var child = select.children[i]; if (child.value == fwidth) { child.selected = "true"; break; } } } </script> <body onload="restore_options()"> Width: <select id="width"> <option value="100%">100%</option> <option value="90%">90%</option> <option value="80%">80%</option> <option value="70%">70%</option> </select> <br> <button onclick="save_options()">Save</button> </body> </html> I also have a background.html file to handle the communication between the content script and the localstorage: <html> <script type="text/javascript"> chrome.extension.onRequest.addListener(function(request, sender, sendResponse) { if (request.method == "siteWidth") sendResponse({status: localStorage["site_width"]}); else sendResponse({}); }); </script> </html> Then there's the actual content script that looks like this: var Width; chrome.extension.sendRequest({method: "siteWidth"}, function(response) { width = response.status; }); None of that code actually works. It looks solid enough to me but I'm not a very experienced programmer so I might be wrong. Could someone explain localstorage to me in layman's terms?

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• Implementing Object Oriented: ansi-C approach

  - by No Money

  Hey there, I am an Intermediate programmer in Java and know some of the basics in C++. I recently started to scam over "C language" [please note that i emphasized on C language and want to stick with C as i found it to be a perfect tool, so no need for suggestions focusing on why should i move back to C++ or Java or any other crappy language (e.g: C#)]. Moving on, I code an Object Oriented approach in C but kindda scramble with the pointers part. Please understand that I am just a noob trying to extend my knowledge beyond what i learned in High School. Here is my code..... #include <stdio.h> typedef struct per{ int privateint; char *privateString; struct per (*New) (); void (*deleteperOBJ) (struct t_person *); void (*setperNumber) ((struct*) t_person,int); void (*setperString) ((struct*) t_person,char *); void (*dumpperState) ((struct*) t_person); }t_person; void setperNumber(t_person *const per,int num){ if(per==NULL) return; per->privateint=num; } void setperString(t_person *const per,char *string){ if(per==NULL) return; per->privateString=string; } void dumpperState(t_person *const per){ if(per==NULL) return; printf("value of private int==%d\n", per->privateint); printf("value of private string==%s\n", per->privateString); } void deleteperOBJ(struct t_person *const per){ free((void*)t_person->per); t_person ->per = NULL; } main(){ t_person *const per = (struct*) malloc(sizeof(t_person)); per = t_person -> struct per -> New(); per -> setperNumber (t_person *per, 123); per -> setperString(t_person *per, "No money"); dumpperState(t_person *per); deleteperOBJ(t_person *per); } Just to warn you, this program has several errors and since I am a beginner I couldn't help except to post this thread as a question. I am looking forward for assistance. Thanks in advance.

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• C++ Class Access Specifier Verbosity

  - by PolyTex

  A "traditional" C++ class (just some random declarations) might resemble the following: class Foo { public: Foo(); explicit Foo(const std::string&); ~Foo(); enum FooState { Idle, Busy, Unknown }; FooState GetState() const; bool GetBar() const; void SetBaz(int); private: struct FooPartialImpl; void HelperFunction1(); void HelperFunction2(); void HelperFunction3(); FooPartialImpl* m_impl; // smart ptr FooState m_state; bool m_bar; int m_baz; }; I always found this type of access level specification ugly and difficult to follow if the original programmer didn't organize his "access regions" neatly. Taking a look at the same snippet in a Java/C# style, we get: class Foo { public: Foo(); public: explicit Foo(const std::string&); public: ~Foo(); public: enum FooState { Idle, Busy, Unknown }; public: FooState GetState() const; public: bool GetBar() const; public: void SetBaz(int); private: struct FooPartialImpl; private: void HelperFunction1(); private: void HelperFunction2(); private: void HelperFunction3(); private: FooPartialImpl* m_impl; // smart ptr private: FooState m_state; private: bool m_bar; private: int m_baz; }; In my opinion, this is much easier to read in a header because the access specifier is right next to the target, and not a bunch of lines away. I found this especially true when working with header-only template code that wasn't separated into the usual "*.hpp/*.inl" pair. In that scenario, the size of the function implementations overpowered this small but important information. My question is simple and stems from the fact that I've never seen anyone else actively do this in their C++ code. Assuming that I don't have a "Class View" capable IDE, are there any obvious drawbacks to using this level of verbosity? Any other style recommendations are welcome!

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• Coping with feelings of technical mediocrity

  - by Karim

  As I've progressed as a programmer, I noticed more nuance and areas I could study in depth. In part, I've come to think of myself from, at one point, a "guru" to now much less, even mediocre or inadequate. Is this normal, or is it a sign of a destructive excessive ambition? Background I started to program when I was still a kid, I had about 10 or 11 years. I really enjoy my work and never get bored from it. It's amazing how somebody could be paid for what he really likes to do and would be doing it anyway even for free. When I first started to program, I was feeling proud of what I was doing, each application I built was for me a success and after 2-3 year I had a feeling that I'm a coding guru. It was a nice feeling. ;-) But the more I was in the field and the more types of software I started to develop, I was starting to have a feeling that I'm completely wrong in thinking I'm a guru. I felt that I'm not even a mediocre developer. Each new field I start to work on is giving me this feeling. Like when I once developed a device driver for a client, I saw how much I need to learn about device drivers. When I developed a video filter for an application, I saw how much do I still need to learn about DirectShow, Color Spaces, and all the theory behind that. The worst thing was when I started to learn algorithms. It was several years ago. I knew then the basic structures and algorithms like the sorting, some types of trees, some hashtables, strings, etc. and when I really wanted to learn a group of structures I learned about 5-6 new types and saw that in fact even this small group has several hundred subtypes of structures. It's depressing how little time people have in their lives to learn all this stuff. I'm now a software developer with about 10 years of experience and I still feel that I'm not a proficient developer when I think about things that others do in the industry.

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• Java loading user-specified classes at runtime

  - by user349043

  I'm working on robot simulation in Java (a Swing application). I have an abstract class "Robot" from which different types of Robots are derived, e.g. public class StupidRobot extends Robot { int m_stupidness; int m_insanityLevel; ... } public class AngryRobot extends Robot { float m_aggression; ... } As you can see, each Robot subclass has a different set of parameters. What I would like to do is control the simulation setup in the initial UI. Choose the number and type of Robots, give it a name, fill in the parameters etc. This is one of those times where being such a dinosaur programmer, and new to Java, I wonder if there is some higher level stuff/thinking that could help me here. So here is what I've got: (1) User Interface Scrolling list of Robot types on the left. "Add " and "<< Remove" buttons in the middle. Default-named scrolling list of Robots on the right. "Set Parameters" button underneath. (So if you wanted an AngryRobot, you'd select AngryRobot on the left list, click "Add" and "AngryRobot1" would show up on the right.) When selecting a Robot on the right, click "Set Parameters..." button which would call yet another model dialog where you'd fill in the parameters. Different dialog called for each Robot type. (2) Data structures an implementation As an end-product I think a HashMap would be most convenient. The keys would be Robot types and the accompanying object would be all of the parameters. The initializer could just retrieve each item one and a time and instantiate. Here's what the data structures would look like: enum ROBOT_TYPE {STUPID, ANGRY, etc} public class RobotInitializer { public ROBOT_TYPE m_type; public string m_name; public int[] m_int_params; public float[] m_float_params; etc. The initializer's constructor would create the appropriate length parameter arrays based on the type: public RobotInitializer(ROBOT_TYPE type, int[] int_array, float[] float_array, etc){ switch (type){ case STUPID: m_int_params = new int[STUPID_INT_PARAM_LENGTH]; System.arraycopy(int_array,0,m_int_params,0,STUPID_INT_PARAM_LENGTH); etc. Once all the RobotInitializers are instantiated, they are added to the HashMap. Iterating through the HashMap, the simulation initializer takes items from the Hashmap and instantiates the appropriate Robots. Is this reasonable? If not, how can it be improved? Thanks

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• A case-insensitive related implementation problem

  - by Robert

  Hi All, I am going through a final refinement posted by the client, which needs me to do a case-insesitive query. I will basically walk through how this simple program works. First of all, in my Java class, I did a fairly simple webpage parsing: title=(String)results.get("title"); doc = docBuilder.parse("http://" + server + ":" + port + "/exist/rest/db/wb/xql/media_lookup.xql?" + "&title=" + title); This Java statement references an XQuery file "media_lookup.xql" which is stored on localhost, and the only parameter we are passing is the string "title". Secondly, let's take at look at that XQuery file: $title := request:get-parameter('title',""), $mediaNodes := doc('/db/wb/portfolio/media_data.xml'), $query := $mediaNodes//media[contains(title,$title)], Then it will evaluate that query. This XQuery will get the "title" parameter that are passes from our Java class, and query the "media_data" xml file stored in the database, which contains a bunch of media nodes with a 'title' element node. As you may expect, this simple query will just match those media nodes whose 'title' element contains a substring of what the value of string 'title' is. So if our 'title' is "Chi", it will return media nodes whose title may be "Chicago" or "Chicken". The refinment request posted by the client is that there should be NO case-sensitivity. The very intuitive way is to modify the XQuery statement by using a lower-case funtion in it, like: $query := $mediaNodes//media[contains(lower-case(title/text(),lower-case($title))], However, the question comes: this modified query will run my machine into memory overflow. Since my "media_data.xml" is quite huge and contains thouands of millions of media nodes, I assume the lower-case() function will run on each of the entries, thus causing the machine to crash. I've talked with some experienced XQuery programmer, and they think I should use an index to solve this problem, and I will definitely research into that. But before that, I am just posting this problem here to get other ideas or any suggestions, do you think any other way may help? for example, could I tweak the Java parse statement to realize the case-insensitivity? Since I think I saw some people did some string concatination by using "contains." in Java before passing it to the server. Any idea or help is welcomed, thanks in advance.

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