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• Some general C questions.

  - by b-gen-jack-o-neill

  Hello. I am trying to fully understand the process pro writing code in some language to execution by OS. In my case, the language would be C and the OS would be Windows. So far, I read many different articles, but I am not sure, whether I understand the process right, and I would like to ask you if you know some good articles on some subjects I couldn´t find. So, what I think I know about C (and basically other languages): C compiler itself handles only data types, basic math operations, pointers operations, and work with functions. By work with functions I mean how to pass argument to it, and how to get output from function. During compilation, function call is replaced by passing arguments to stack, and than if function is not inline, its call is replaced by some symbol for linker. Linker than find the function definition, and replace the symbol to jump adress to that function (and of course than jump back to program). If the above is generally true and I get it right, where to final .exe file actually linker saves the functions? After the main() function? And what creates the .exe header? Compiler or Linker? Now, additional capabilities of C, today known as C standart library is set of functions and the declarations of them, that other programmers wrote to extend and simplify use of C language. But these functions like printf() were (or could be?) written in different language, or assembler. And there comes my next question, can be, for example printf() function be written in pure C without use of assembler? I know this is quite big question, but I just mostly want to know, wheather I am right or not. And trust me, I read a lots of articles on the web, and I would not ask you, If I could find these infromation together on one place, in one article. Insted I must piece by piece gather informations, so I am not sure if I am right. Thanks.

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• EF 4.0 : Save Changes Retry Logic

  - by BGR

  Hi, I would like to implement an application wide retry system for all entity SaveChanges method calls. Technologies: Entity framework 4.0 .Net 4.0 namespace Sample.Data.Store.Entities { public partial class StoreDB { public override int SaveChanges(System.Data.Objects.SaveOptions options) { for (Int32 attempt = 1; ; ) { try { return base.SaveChanges(options); } catch (SqlException sqlException) { // Increment Trys attempt++; // Find Maximum Trys Int32 maxRetryCount = 5; // Throw Error if we have reach the maximum number of retries if (attempt == maxRetryCount) throw; // Determine if we should retry or abort. if (!RetryLitmus(sqlException)) throw; else Thread.Sleep(ConnectionRetryWaitSeconds(attempt)); } } } static Int32 ConnectionRetryWaitSeconds(Int32 attempt) { Int32 connectionRetryWaitSeconds = 2000; // Backoff Throttling connectionRetryWaitSeconds = connectionRetryWaitSeconds * (Int32)Math.Pow(2, attempt); return (connectionRetryWaitSeconds); } /// <summary> /// Determine from the exception if the execution /// of the connection should Be attempted again /// </summary> /// <param name="exception">Generic Exception</param> /// <returns>True if a a retry is needed, false if not</returns> static Boolean RetryLitmus(SqlException sqlException) { switch (sqlException.Number) { // The service has encountered an error // processing your request. Please try again. // Error code %d. case 40197: // The service is currently busy. Retry // the request after 10 seconds. Code: %d. case 40501: //A transport-level error has occurred when // receiving results from the server. (provider: // TCP Provider, error: 0 - An established connection // was aborted by the software in your host machine.) case 10053: return (true); } return (false); } } } The problem: How can I run the StoreDB.SaveChanges to retry on a new DB context after an error occured? Something simular to Detach/Attach might come in handy. Thanks in advance! Bart

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• Function approximation with Maclaurin series

  - by marines

  I need to approx (1-x)^0.25 with given accuracy (0.0001 e.g.). I'm using expansion found on Wikipedia for (1+x)^0.25. I need to stop approximating when current expression is less than the accuracy. long double s(long double x, long double d) { long double w = 1; long double n = 1; // nth expression in series long double tmp = 1; // sum while last expression is greater than accuracy while (fabsl(tmp) >= d) { tmp *= (1.25 / n - 1) * (-x); // the next expression w += tmp; // is added to approximation n++; } return w; } Don't mind long double n. :P This works well when I'm not checking value of current expression but when I'm computing 1000 or more expressions. Domain of the function is <-1;1 and s() calculates approximation well for x in <-1;~0.6. The bigger the argument is the bigger is the error of calculation. From 0.6 it exceeds the accuracy. I'm not sure if the problem is clear enough because I don't know English math language well. The thing is what's the matter with while condition and why the function s() doesn't approximate correctly.

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• ORM model and DAO in my particular case

  - by EugeneP

  I have the DB structure as follows: table STUDENT (say, id, surname, etc) table STUDENT_PROPERTIES (say, name_of_the_property:char, value_of_the_property:char, student_id:FK) table COURSE (id, name, statusofcourse_id) table STATUSOFCOURSE (id, name_of_status:char ('active','inactive','suspended' etc)) table STUDENT_COURSE (student_id,course_id,statusofcourse_id) Let's try to pick up domain objects in my database: Student and Course are main entities. Student has a list of courses he attends, also he has a list of properties, that is all for this student. Next, Course entitity. It may contain a list of students that attend it. But in fact, the whole structure looks like this: the starting point is Student, with it's PK we can look a list of his properties, then we look into the STUDENT_COURSE and extract both FK of the Course entity and also the Status of the combination, it would look like "Student named bla bla, with all his properties, attends math and the status of it is "ACTIVE". now, quotation 1) Each DAO instance is responsible for one primary domain object or entity. If a domain object has an independent lifecycle, it should have its own DAO. 2) The DAO is responsible for creations, reads (by primary key), updates, and deletions -- that is, CRUD -- on the domain object. Now, first question is What are entities in my case? Student, Course, Student_Course, Status = all except for StudentProperties? Do I have to create a separate DAO for every object?

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• Calculation Expression Parser with Nesting and Variables in ActionScript

  - by yuletide

  Hi There, I'm trying to enable dynamic fields in the configuration file for my mapping app, but I can't figure out how to parse the "equation" passed in by the user, at least not without writing a whole parser from scratch! I'm sure there is some easier way to do this, and so I'm asking for ideas! Basic idea: public var testString:String = "(#TOTPOP_CY#-#HISPOP_CY#)/#TOTPOP_CY#"; public var valueObject:Object = {TOTPOP_CY:1000, HISPOP_CY:100}; public function calcParse(eq:String):String { // do calculations return calculatedValue } So far, I was thinking of splitting the expression by either the operators, or maybe the variable tokens, but that gets rid of the parenthetical nesting. Alternatively, use a series of regex to search and replace each piece of the expression with its value, recursively running until only a number is left. But I don't think regex does math (i.e. replace "\d + \d" with the sum of the two numbers) Ideally, I'd just do a find/replace all variable names with their values, then run an eval(), but there's no eval in AS... eesh I downloaded some course materials for a course on compiler design, so maybe I'll just write a full-fledged calculator language and parser and port it over from the OTHER flex (the parser generator) :-D

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• Beginner problems with references to arrays in python 3.1.1

  - by Protean

  As part of the last assignment in a beginner python programing class, I have been assigned a traveling sales man problem. I settled on a recursive function to find each permutation and the sum of the distances between the destinations, however, I am have a lot of problems with references. Arrays in different instances of the Permute and Main functions of TSP seem to be pointing to the same reference. from math import sqrt class TSP: def __init__(self): self.CartisianCoordinates = [['A',[1,1]], ['B',[2,2]], ['C',[2,1]], ['D',[1,2]], ['E',[3,3]]] self.Array = [] self.Max = 0 self.StoredList = ['',0] def Distance(self, i1, i2): x1 = self.CartisianCoordinates[i1][1][0] y1 = self.CartisianCoordinates[i1][1][1] x2 = self.CartisianCoordinates[i2][1][0] y2 = self.CartisianCoordinates[i2][1][1] return sqrt(pow((x2 - x1), 2) + pow((y2 - y1), 2)) def Evaluate(self): temparray = [] Data = [] for i in range(len(self.CartisianCoordinates)): Data.append([]) for i1 in range(len(self.CartisianCoordinates)): for i2 in range(len(self.CartisianCoordinates)): if i1 != i2: temparray.append(self.Distance(i1, i2)) else: temparray.append('X') Data[i1] = temparray temparray = [] self.Array = Data self.Max = len(Data) def Permute(self,varray,index,vcarry,mcarry): #Problem Class array = varray[:] carry = vcarry[:] for i in range(self.Max): print ('ARRAY:', array) print (index,i,carry,array[index][i]) if array[index][i] != 'X': carry[0] += self.CartisianCoordinates[i][0] carry[1] += array[index][i] if len(carry) != self.Max: temparray = array[:] for j in range(self.Max):temparray[j][i] = 'X' index = i mcarry += self.Permute(temparray,index,carry,mcarry) else: return mcarry print ('pass',mcarry) return mcarry def Main(self): out = [] self.Evaluate() for i in range(self.Max): array = self.Array[:] #array appears to maintain the same reference after each copy, resulting in an incorrect array being passed to Permute after the first iteration. print (self.Array[:]) for j in range(self.Max):array[j][i] = 'X' print('I:', i, array) out.append(self.Permute(array,i,[str(self.CartisianCoordinates[i][0]),0],[])) return out SalesPerson = TSP() print(SalesPerson.Main()) It would be greatly appreciated if you could provide me with help in solving the reference problems I am having. Thank you.

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• Job Opportunities

  - by James

  I have a few questions about my job opportunities and I appreaciate it if people could give me some feedback on what I should have in front of me. I am graduatating from a University of Wisconsin--La Crosse this December with a degree in CS and a math minor. I have a cumulative GPA of 3.84 and a major GPA of 4.0 right now (though I still have many classes in front of me). I already have a degree from the U of Minnesota (History, 3.69 GPA) and have worked in the business world for 3+ years (working for a small company in the baseball world, doing some computer programming, statistical research, operations work, technical writing, etc.) I know Java and C well, also am comfortable with Perl. I should have a good grasp of SQL by graduation. I am looking to get a nice programming job (and will be open to moving). Anyone have any advice on things I should learn etc? Also, I would like to know what everyone thinks about my chances of landing a decent job (I realize that is subjective). Also, any ideas on salary I should be looking for (say I am working a metropolitan area). Thanks.

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• Formula parsing / evaluation routine or library with generic DLookup functionality

  - by tbone

  I am writing a .Net application where I must support user-defined formulas that can perform basic mathematics, as well as accessing data from any arbitrary table in the database. I have the math part working, using JScript Eval(). What I haven't decided on is what a nice way is to do the generic table lookups. For example, I may have a formula something like: Column: BonusAmount Formula: {CurrentSalary} * 1.5 * {[SystemSettings][Value][SettingName=CorpBonus AND Year={Year}]} So, in this example I would replace {xxx} and {Year} with the value of Column xxx from the current table, and I would replace the second part with the value of (select Value from SystemSettings WHERE SettingName='CorpBonus' AND Year=2008) So, basically, I am looking for something very much like the MS Access DLookup function: DLookup ( expression, domain, [criteria] ) DLookup("[UnitPrice]", "Order Details", "OrderID = 10248") But, I also need to overall parsing routine that can tell whether to just look up in the current row, or to look into another table. Would also be nice to support aggregate functions (ie: DAvg, DMax, etc), as well as all the weird edge cases handled. So I wonder if anyone knows of any sort of an existing library, or has a nice routine that can handle this formula parsing and database lookup / aggregate function resolution requirements.

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• SSIS 2005 Error while using script component Designer: "Cannot fetch a row from OLE DB provider "BUL

  - by user150541

  I am trying to debug a dts package in SSIS. I have a script component designer where I pass in the input variables to increment a counter. When I try to msgbox the counter value, I get the following error. Error: 0xC0202009 at STAGING1 to STAGING2, STAGING2 Destination [1056]: An OLE DB error has occurred. Error code: 0x80040E14. An OLE DB record is available. Source: "Microsoft SQL Native Client" Hresult: 0x80040E14 Description: "Cannot fetch a row from OLE DB provider "BULK" for linked server "(null)".". An OLE DB record is available. Source: "Microsoft SQL Native Client" Hresult: 0x80040E14 Description: "The OLE DB provider "BULK" for linked server "(null)" reported an error. The provider did not give any information about the error.". An OLE DB record is available. Source: "Microsoft SQL Native Client" Hresult: 0x80040E14 Description: "Reading from DTS buffer timed out.". Below is the part of the code within the script component designer : Imports System Imports System.Data Imports System.Math Imports Microsoft.SqlServer.Dts.Pipeline.Wrapper Imports Microsoft.SqlServer.Dts.Runtime.Wrapper Public Class ScriptMain Inherits UserComponent Dim iCounter As Integer Dim iCurrentVal As Integer Dim sCurrentOracleSeq As String Dim sSeqName As String Dim sSeqAltProcName As String Public Overrides Sub Input0_ProcessInputRow(ByVal Row As Input0Buffer) ' ' Add your code here ' Row.SEQIDNCASE = iCounter + iCurrentVal iCounter += 1 MsgBox(iCounter + iCurrentVal, MsgBoxStyle.Information, "Input0") End Sub Public Overrides Sub PreExecute() sCurrentOracleSeq = Me.Variables.VSEQIDCurVal iCurrentVal = CInt(sCurrentOracleSeq) MsgBox(iCurrentVal, MsgBoxStyle.Information, "No Title") iCounter = 0 sSeqName = Me.Variables.VSEQIDName sSeqAltProcName = Me.Variables.VSEQIDAlterProc End Sub Public Overrides Sub PostExecute() Me.Variables.VSEQIDUpdateSQL = "Begin " & sSeqAltProcName & "('" & sSeqName & "'," & (iCounter + iCurrentVal) & "); End;" End Sub End Class Note that the above part of code works perfectly fine if I comment out the lines that has Msgbox.

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• ai: Determining what tests to run to get most useful data

  - by Sai Emrys

  This is for http://cssfingerprint.com I have a system (see about page on site for details) where: I need to output a ranked list, with confidences, of categories that match a particular feature vector the binary feature vectors are a list of site IDs & whether this session detected a hit feature vectors are, for a given categorization, somewhat noisy (sites will decay out of history, and people will visit sites they don't normally visit) categories are a large, non-closed set (user IDs) my total feature space is approximately 50 million items (URLs) for any given test, I can only query approx. 0.2% of that space I can only make the decision of what to query, based on results so far, ~10-30 times, and must do so in <~100ms (though I can take much longer to do post-processing, relevant aggregation, etc) getting the AI's probability ranking of categories based on results so far is mildly expensive; ideally the decision will depend mostly on a few cheap sql queries I have training data that can say authoritatively that any two feature vectors are the same category but not that they are different (people sometimes forget their codes and use new ones, thereby making a new user id) I need an algorithm to determine what features (sites) are most likely to have a high ROI to query (i.e. to better discriminate between plausible-so-far categories [users], and to increase certainty that it's any given one). This needs to take into balance exploitation (test based on prior test data) and exploration (test stuff that's not been tested enough to find out how it performs). There's another question that deals with a priori ranking; this one is specifically about a posteriori ranking based on results gathered so far. Right now, I have little enough data that I can just always test everything that anyone else has ever gotten a hit for, but eventually that won't be the case, at which point this problem will need to be solved. I imagine that this is a fairly standard problem in AI - having a cheap heuristic for what expensive queries to make - but it wasn't covered in my AI class, so I don't actually know whether there's a standard answer. So, relevant reading that's not too math-heavy would be helpful, as well as suggestions for particular algorithms. What's a good way to approach this problem?

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• How to temporarily replace one primitive type with another when compiling to different targets in c#

  - by Keith

  How to easily/quickly replace float's for doubles (for example) for compiling to two different targets using these two particular choices of primitive types? Discussion: I have a large amount of c# code under development that I need to compile to alternatively use float, double or decimals depending on the use case of the target assembly. Using something like “class MYNumber : Double” so that it is only necessary to change one line of code does not work as Double is sealed, and obviously there is no #define in C#. Peppering the code with #if #else statements is also not an option, there is just too much supporting Math operators/related code using these particular primitive types. I am at a loss on how to do this apparently simple task, thanks! Edit: Just a quick comment in relation to boxing mentioned in Kyles reply: Unfortunately I need to avoid boxing, mainly since float's are being chosen when maximum speed is required, and decimals when maximum accuracy is the priority (and taking the 20x+ performance hit is acceptable). Boxing would probably rules out decimals as a valid choice and defeat the purpose somewhat. Edit2: For reference, those suggesting generics as a possible answer to this question note that there are many issues which count generics out (at least for our needs). For an overview and further references see Using generics for calculations

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• Changing text of TextView -- old text doesn't go away (Android 4.1.2)

  - by Jason Costabile

  I'm pretty new to Android development. Trying to accomplish something fairly simple -- change some displayed text when a timer ticks. Here's the potentially relevant code: CountDownTimer currentTimer; Resources res; TextView timerText; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_exercise); res = getResources(); timerText = (TextView) findViewById(R.id.timer_text); } @Override protected void onStart() { super.onStart(); //"Get ready" countdown currentTimer = new CountDownTimer(5000, 1000) { @Override public void onTick(long millisUntilFinished) { timerText.setText("" + (int)Math.ceil(millisUntilFinished / 1000.0)); } @Override public void onFinish() { ... } }; currentTimer.start(); } This works fine on an emulated 4.2.2 device, but on a 4.1.2 device (both physical and emulated), the changed TextView appears as such while the countdown proceeds: If you can't tell, that's the numbers 5,4,3 overlayed. So, when I set a new string for the TextView, the new string is displayed but without replacing the old string. Any other TextViews used in my app behave in the same way. Any ideas what the problem is and how to fix it? Edit: From the XML layout file: <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" tools:context=".ExerciseActivity" android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center" android:keepScreenOn="true" android:orientation="vertical" > ... <TextView android:id="@+id/timer_text" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:textIsSelectable="false" android:hint="@string/timer_default" /> ... </LinearLayout> That's all that could be relevant.

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• Can a GeneralPath be modified?

  - by Dov

  java2d is fairly expressive, but requires constructing lots of objects. In contrast, the older API would let you call methods to draw various shapes, but lacks all the new features like transparency, stroke, etc. Java has fairly high costs associated with object creation. For speed, I would like to create a GeneralPath whose structure does not change, but go in and change the x,y points inside. path = new GeneralPath(GeneralPath.WIND_EVEN_ODD, 10); path.moveTo(x,y); path.lineTo(x2, y2); double len = Math.sqrt((x2-x)*(x2-x) + (y2-y)*(y2-y)); double dx = (x-x2) * headLen / len; double dy = (y-y2) * headLen / len; double dx2 = -dy * (headWidth/headLen); double dy2 = dx * (headWidth/headLen); path.lineTo(x2 + dx + dx2, y2 + dy + dy2); path.moveTo(x2 + dx - dx2, y2 + dy - dy2); path.lineTo(x2,y2); This one isn't even that long. Imagine a much longer sequence of commands, and only the ones on the end are changing. I just want to be able to overwrite commands, to have an iterator effectively. Does that exist?

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• OpenGL - drawing 2D polygons shapes with texture

  - by plonkplonk

  I am trying to make a few effects in a C+GL game. So far I draw all my sprites as a quad, and it works. However, I am trying to make a large ring appear at times, with a texture following that ring, as it takes less memory than a quad with the ring texture inside. The type of ring I want to make is not a round-shaped GL mesh ring (the "tube" type) but a "paper" 2D ring. That way I can modify the "width" of the ring, getting more of the effect than a simple quad+ring texture. So far all my attempts have been...kind of ridiculous, as I don't understand GL's coordinates too well (and I can't really understand the available documentation...I am just a designer with no coder help or background. A n00b, basically). glBegin(GL_POLYGON); for(i = 0;i < 360; i += 10){ glTexCoord2f(0, 0); glVertex2f(Cos(i)*(H-10),Sin(i)H); glTexCoord2f(0, HP); glVertex2f(Sin(i)(H-10),Cos(i)*(H-10)); glTexCoord2f(WP, HP); glVertex2f(Cos(i)H,Sin(i)(H-10)); glTexCoord2f(WP, 0); glVertex2f(Sin(i)*H,Cos(i)*H); } glEnd(); This is my last attempt, and it seems to generate a "sunburst" from the right edge of the circle instead of a ring. It's an amusing effect but definitely not what I want. Other results included the circle looking exactly the same as the quad textured (aka drawing a sprite literally) or something that looked like a pop-art filter, by working on this train of thought. Seems like my logic here is entirely flawed, so, what would be the easiest way to obtain such a ring? No need to reply in code, just some guidance for a non-math-skilled user...

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• Connecting repeatable and non-repeatble backgrounds without a seam

  - by Stiggler

  I have a 700x300 background repeating seamlessly inside of the main content-div. Now I'd like to attach a div at the bottom of the content-div, containing a different background image that isn't repeatable, connecting seamlessly with the repeatable background above it. Essentially, the non-repeatable image will look like the end piece of the repeatable image. Due to the nature of the pattern, unless the full 300px height of the background image is visible in the last repeat of the content-div's backround, the background in the div below won't seamlessly connect. Basically, I need the content div's height to be a multiple of 300px under all circumstances. What's a good approach to this sort of problem? I've tried resizing the content-div on loading the page, but this only works as long as the content div doesn't contain any resizing, dynamic content, which is not my case: function adjustContentHeight() { // Setting content div's height to nearest upper multiple of column backgrounds height, // forcing it not to be cut-off when repeated. var contentBgHeight = 300; var contentHeight = $("#content").height(); var adjustedHeight = Math.ceil(contentHeight / contentBgHeight); $("#content").height(adjustedHeight * contentBgHeight); } $(document).ready(adjustContentHeight); What I'm looking for there is a way to respond to a div resizing event, but there doesn't seem to be such a thing. Also, please assume I have no access to the JS controlling the resizing of content in the content-div, though this is potentially a way of solving the problem. Another potential solution I was thinking off was to offset the background image in the bottom div by a certain amount depending on the height of the content-div. Again, the missing piece seems to be the ability to respond to a resize event.

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• Compute the Length of Largest substring that starts and ends with the same substring

  - by Deepak

  Hi People, Below is the Problem Statement: PS: Given a string and a non-empty substring sub, compute recursively the largest substring which starts and ends with sub and return its length. Examples: strDist("catcowcat", "cat") ? 9 strDist("catcowcat", "cow") ? 3 strDist("cccatcowcatxx", "cat") ? 9 Below is my Code: (Without recursion)//since i found it hard to implement with recursion. public int strDist(String str, String sub){ int idx = 0; int max; if (str.isEmpty()) max = 0; else max=1; while ((idx = str.indexOf(sub, idx)) != -1){ int previous=str.indexOf(sub, idx); max = Math.max(max,previous); idx++; } return max; } Its working for few as shown below but returns FAIL for others. Expected This Run strDist("catcowcat", "cat") ? 9 6 FAIL strDist("catcowcat", "cow") ? 3 3 OK strDist("cccatcowcatxx", "cat") ? 9 8 FAIL strDist("abccatcowcatcatxyz", "cat") ? 12 12 OK strDist("xyx", "x") ? 3 2 FAIL strDist("xyx", "y") ? 1 1 OK strDist("xyx", "z") ? 0 1 FAIL strDist("z", "z") ? 1 1 OK strDist("x", "z") ? 0 1 FAIL strDist("", "z") ? 0 0 OK strDist("hiHellohihihi", "hi") ? 13 11 FAIL strDist("hiHellohihihi", "hih") ? 5 9 FAIL strDist("hiHellohihihi", "o") ? 1 6 FAIL strDist("hiHellohihihi", "ll") ? 2 4 FAIL Could you let me whats wrong with the code and how to return the largest substring that begins and ends with sub with its respective length.

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• How to force c# binary int division to return a double?

  - by Wayne

  How to force double x = 3 / 2; to return 1.5 in x without the D suffix or casting? Is there any kind of operator overload that can be done? Or some compiler option? Amazingly, it's not so simple to add the casting or suffix for the following reason: Business users need to write and debug their own formulas. Presently C# is getting used like a DSL (domain specific language) in that these users aren't computer science engineers. So all they know is how to edit and create a few types of classes to hold their "business rules" which are generally just math formulas. But they always assume that double x = 3 / 2; will return x = 1.5 however in C# that returns 1. A. they always forget this, waste time debugging, call me for support and we fix it. B. they think it's very ugly and hurts the readability of their business rules. As you know, DSL's need to be more like natural language. Yes. We are planning to move to Boo and build a DSL based on it but that's down the road. Is there a simple solution to make double x = 3 / 2; return 1.5 by something external to the class so it's invisible to the users? Thanks! Wayne

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• How to force c# binary int division to return a double?

  - by Wayne

  How to force double x = 3 / 2; to return 1.5 in x without the D suffix or casting? Is there any kind of operator overload that can be done? Or some compiler option? Amazingly, it's not so simple to add the casting or suffix for the following reason: Business users need to write and debug their own formulas. Presently C# is getting used like a DSL (domain specific language) in that these users aren't computer science engineers. So all they know is how to edit and create a few types of classes to hold their "business rules" which are generally just math formulas. But they always assume that double x = 3 / 2; will return x = 1.5 however in C# that returns 1. A. they always forget this, waste time debugging, call me for support and we fix it. B. they think it's very ugly and hurts the readability of their business rules. As you know, DSL's need to be more like natural language. Yes. We are planning to move to Boo and build a DSL based on it but that's down the road. Is there a simple solution to make double x = 3 / 2; return 1.5 by something external to the class so it's invisible to the users? Thanks! Wayne

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• Generic function pointers in C

  - by Lucas

  I have a function which takes a block of data and the size of the block and a function pointer as argument. Then it iterates over the data and performes a calculation on each element of the data block. The following is the essential outline of what I am doing: int myfunction(int* data, int size, int (*functionAsPointer)(int)){ //walking through the data and calculating something for (int n = 0; n < size; n++){ data[n] = (*function)(data[n]); } } The functions I am passing as arguments look something like this: int mycalculation(int input){ //doing some math with input //... return input; } This is working well, but now I need to pass an additional variable to my functionpointer. Something along the lines int mynewcalculation(int input, int someVariable){ //e.g. input = input * someVariable; //... return input; } Is there an elegant way to achieve this and at the same time keeping my overall design idea?

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• MIDP 2.0 version issues: $method is undefined for $type

  - by Kilnr

  Hi, I've written a MIDlet that does several "advanced" things: fetching images from the web, resizing them, saving them on the phone, displaying them. This all works perfectly in the Nokia S60 3rd Edition FP1 emulator. This device has MIDP 2.0 and CLDC 1.1 support (also JSR75, which I need in order to save files). It also works as it should on the Nokia E71 (physical device). I then tried to run the MIDlet on several other emulators. One of them, the DefaultCldcJtwiPhone2 from the Java ME SDK 3.0, also claims MIDP 2.0 and CLDC 1.1 support. It doesn't have JSR75, which explains why "FileConnection can not be resolved to a type". This does not, however, explain why List.deleteAll(), String.equalsIgnoreCase(String) and a few others are undefined. The actual errors that I get: The method ceil(double) is undefined for the type Math The method deleteAll() is undefined for the type List The method equalsIgnoreCase(String) is undefined for the type String The method getWidth() is undefined for the type Displayable When I look at the MIDP 2.0 (i.e. JSR118) API (http://java.sun.com/javame/reference/apis/jsr118/), I can clearly see all of these methods being present, with the "since" tag being either MIDP 2.0 or CLDC 1.1. My question: why doesn't an emulator with MIDP 2.0 support have access to all MIDP 2.0 methods? Or alternatively, what am I doing wrong?

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• How do I find the most “Naturally" direct route using A-star (A*)

  - by Greg B

  I have implemented the A* algorithm in AS3 and it works great except for one thing. Often the resulting path does not take the most “natural” or smooth route to the target. In my environment the object can move diagonally as inexpensively as it can move horizontally or vertically. Here is a very simple example; the start point is marked by the S, and the end (or finish) point by the F. | | | | | | | | | | |S| | | | | | | | | x| | | | | | | | | | x| | | | | | | | | | x| | | | | | | | | | x| | | | | | | | | | x| | | | | | | | | | |F| | | | | | | | | | | | | | | | | | | | | | | | | | | | | As you can see, during the 1st round of finding, nodes [0,2], [1,2], [2,2] will all be added to the list of possible node as they all have a score of N. The issue I’m having comes at the next point when I’m trying to decide which node to proceed with. In the example above I am using possibleNodes[0] to choose the next node. If I change this to possibleNodes[possibleNodes.length-1] I get the following path. | | | | | | | | | | |S| | | | | | | | | | |x| | | | | | | | | | |x| | | | | | | | | | |x| | | | | | | | |x| | | | | | | | |x| | | | | | | | |F| | | | | | | | | | | | | | | | | | | | | | | | | | | | | And then with possibleNextNodes[Math.round(possibleNextNodes.length / 2)-1] | | | | | | | | | | |S| | | | | | | | | |x| | | | | | | | | x| | | | | | | | | | x| | | | | | | | | | x| | | | | | | | | | x| | | | | | | | | | |F| | | | | | | | | | | | | | | | | | | | | | | | | | | | | All these paths have the same cost as they all contain the same number of steps but, in this situation, the most sensible path would be as follows... | | | | | | | | | | |S| | | | | | | | | |x| | | | | | | | | |x| | | | | | | | | |x| | | | | | | | | |x| | | | | | | | | |x| | | | | | | | | |F| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Is there a formally accepted method of making the path appear more sensible rather than just mathematically correct?

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• If I wanted to make a Pac-Man Game?

  - by SoulBeaver

  I am immediately placing this as a community wiki thing. I don't want to ask for help in programming yet or have even a specific question about programming, but rather the process and the resources needed to make such a game. To put it simply: My college friend and I decided to give ourselves a really big challenge to further our skills in programming. In six months time we want to show ourselves a Pac-Man game. Pac-Man will be AI-controlled like the Ghosts and whichever Pac-Man lives the longest after a set of tries wins. This isn't like anything we've done so far. The goal here, for me, isn't to create a perfect game, but to try and complete it, learn a whole bunch in the process. Even if I don't finish in the time, which is a good possibility, I would want to have at least tried this. So my question is this: How should I start preparing myself? I already have started vector math, matrices, all that fun stuff. My desired platform would be DirectX 9.0c; is that advisable? Keep in mind that this is not a preference just for this project, but I wish to have some kind of future in graphics develepment, so I want to pick a platform that is future-safe. As for the game development in general, what should I take into consideration? I have never done a real game before, so any and all advise to development of mid-scale projects( if this would be a mid-scale project ) is greatly appreciated. My main concerns are the pit-falls and demotivators. Sorry if the question is so vague. If it doesn't belong here, then I will remove it. Otherwise, any and all advise regarding making larger projects is greatly appreciated.

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• create TableModel and populate jTable dynamically

  - by Julia

  Hi all! I want to store the results of reading lucene index into jTable, so that I can make it sortable by different columns. From index I am reading terms with different measures of their frequencies. Table columns are these : [string term][int absFrequency][int docFrequency][double invFrequency] So i in AbstractTableModel I can define column names, but i dont know how to get the Object[][]data with results from the following method: public static void FrequencyMap(Directory indexDir) throws Exception { List<Object>redoviLista = new ArrayList<Object>(); //final Map<String,TermRow> map = new TreeMap<String,TermRow>(); List<String>termList = new ArrayList<String>(); IndexReader iReader = IndexReader.open(indexDir); FilterIndexReader fReader = new FilterIndexReader(iReader); int numOfDocs = fReader.numDocs(); TermEnum terms = fReader.terms(); while (terms.next()){ Term term = terms.term(); String termText = term.text(); termList.add(termText); //Calculating the frequencies int df = iReader.docFreq(term); double idf = 0.0F; idf = Math.log10((double) numOfDocs / df); double tfidf = (df*idf); //Here comes important part Object oneTableRow[] = {termText, df, idf, tfidf}; redoviLista.add(jedanRed); // So i thaught to store them into list, and then later to copy into table, but didnt manage } iReader.close(); // So I need something like this, and i Neeed this array to be stored out of this method Object[][]data = new Object[redoviLista.size()][]; for (int i = 0; i < data.length; i++) { data[i][0] = redoviLista.get(i); } So I am kindda stuck here to proceed to implement AbstractTableModel and populate and display this table .... :/ Please help!

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• PHP APC and Pecl upload progress returning false/null.

  - by Keyo

  This is a long shot. I believe this might be suhosin patch issue. Here is my php from codeigniter: public function uploadprogress($id) { if ($id) { header("Cache-Control: no-cache, must-revalidate"); header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); echo json_encode(apc_fetch('upload_'.$id)); exit(); } } public function uploader() { $this->load->view('myid/' . $this->router->class . '_uploader'); //phpinfo(); } script: <script type="text/javascript"> $(document).ready(function(){ var progress_key = $('#progress_key').val(); // this sets up the progress bar $('#uploadform').submit(function() { setTimeout(beginUpload,1500); return; }); function beginUpload() { $("#progressbar").progressbar({ value:0}).fadeIn(); var i = setInterval(function() { $.getJSON("/myid/videos/uploadprogress/" + progress_key, function(data) { alert('data'); if (data == null) { clearInterval(i); location.reload(true); return; } var response; eval ("response = " + data); if (!response) return; var percentage = Math.floor(100 * parseInt(response['bytes_uploaded']) / parseInt(response['bytes_total'])); $("#progressbar").progressbar({value:percentage}); }, 1500); }); } }); </script> Has anyone had strange troubles with this before? The upload key is the same on the view and the uploadprogress method. I've Tried apc and pecl upload-progress both return false or null. I wondering if it's just suhosin patch messing up everything?

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• Why when I render a scene with a revolving camera objects that you'd expect to appear behind others

  - by seaworthy

  Hello, I am rendering a scene in which I have two spheres. I am revolving a camera around one of them. What happens is counter-intuitive. When the camera goes around the sphere the other gets in front of it when you'd expect it to be behind. So it appears as though the spheres aren't revolving around each other and the one the should go around is always upfront. Please help. Here is the code that renders the scene: glLoadIdentity(); [self positionCamera]; glutSolidSphere(2, 12,12); glPushMatrix(); glTranslatef(5, 0, 0); glutSolidSphere(0.5, 12,12); glPopMatrix(); glFlush(); This block is part of a class that gets called on using. [NSTimer scheduledTimerWithTimeInterval:DEFAULT_ANIMATION_INTERVAL target:self selector:@selector(drawRect) userInfo:nil repeats:YES]; And -(void)positionCamera{} Contains math do camera revolution and gluLookAt()

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