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  • Bluetooth to arduino

    - by user1833709
    My current project includes an Arduino Uno attached via USB to a laptop. The laptop is there is receive messages via bluetooth (I realize I could connect a bluetooth modem directly to the arduino but this project has to come in under budget). What I'd ideally like to do is write a program that continually checks whether the laptop has been paired to a bluetooth transmitter (my phone) and sends this to the arduino. Do you think should write a program that checks the bluetooth state and writes a 0 or 1 to a text document, and then use something like Gobetwino to read from the text document? I could probably figure out how to continually read from the file, but I don't know enough about bluetooth to know how to check whether it's paired or not, computer-side. Something that writes directly to the arduino instead of a text document would be my preference, but I don't know where to start. I'm using an Android phone and Windows 7. If you need more info about the setup, just ask. Does anyone have any experience with this?

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  • C++: best way to implement globally scoped data

    - by bobobobo
    I'd like to make program-wide data in a C++ program, without running into pesky LNK2005 errors when all the source files #includes this "global variable repository" file. I have 2 ways to do it in C++, and I'm asking which way is better. The easiest way to do it in C# is just public static members. C#: public static class DataContainer { public static Object data1 ; public static Object data2 ; } In C++ you can do the same thing C++ global data way#1: class DataContainer { public: static Object data1 ; static Object data2 ; } ; Object DataContainer::data1 ; Object DataContainer::data2 ; However there's also extern C++ global data way #2: class DataContainer { public: Object data1 ; Object data2 ; } ; extern DataContainer * dataContainer ; // instantiate in .cpp file In C++ which is better, or possibly another way which I haven't thought about? The solution has to not cause LNK2005 "object already defined" errors.

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  • Projective transformation

    - by mcwehner
    Given two image buffers (assume it's an array of ints of size width * height, with each element a color value), how can I map an area defined by a quadrilateral from one image buffer into the other (always square) image buffer? I'm led to understand this is called "projective transformation". I'm also looking for a general (not language- or library-specific) way of doing this, such that it could be reasonably applied in any language without relying on "magic function X that does all the work for me". An example: I've written a short program in Java using the Processing library (processing.org) that captures video from a camera. During an initial "calibrating" step, the captured video is output directly into a window. The user then clicks on four points to define an area of the video that will be transformed, then mapped into the square window during subsequent operation of the program. If the user were to click on the four points defining the corners of a door visible at an angle in the camera's output, then this transformation would cause the subsequent video to map the transformed image of the door to the entire area of the window, albeit somewhat distorted.

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  • Is this a hole in dynamic binding in C# 4?

    - by Galilyou
    I've seen a very interesting post on Fabio Maulo's blog. Here's the code and the bug if you don't want to jump to the url. I defined a new generic class like so: public class TableStorageInitializer<TTableEntity> where TTableEntity : class, new() { public void Initialize() { InitializeInstance(new TTableEntity()); } public void InitializeInstance(dynamic entity) { entity.PartitionKey = Guid.NewGuid().ToString(); entity.RowKey = Guid.NewGuid().ToString(); } } Note that InitializeInstance accepts one parameter, which is of type dynamic. Now to test this class, I defined another class that is nested inside my main Program class like so: class Program { static void Main(string[] args) { TableStorageInitializer<MyClass> x = new TableStorageInitializer<MyClass>(); x.Initialize(); } private class MyClass { public string PartitionKey { get; set; } public string RowKey { get; set; } public DateTime Timestamp { get; set; } } } Note: the inner class "MyClass" is declared private. Now if i run this code I get a "Microsoft.CSharp.RuntimeBinder.RuntimeBinderException" on the line "entity.PartitionKey = Guide.NewGuid().ToString()". The interesting part, though is that the message of the exception says "Object doesn't contain a definition for PartitionKey". Also note that if you changed the modifier of the nested class to public, the code will execute with no problems. So what do you guys think is really happening under the hood? Please refer to any documentation -of course if this is documented anywhere- that you may find?

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  • Problem with close socket

    - by zp26
    Hi, I have a problem with my socket program. I create the client program (my code is below) I have a problem when i close the socket with the disconnect method. Can i help me? Thanks and sorry for my English XP CFSocketRef s; -(void)CreaConnessione { CFSocketError errore; struct sockaddr_in sin; CFDataRef address; CFRunLoopSourceRef source; CFSocketContext context = { 0, self, NULL, NULL, NULL }; s = CFSocketCreate( NULL, PF_INET, SOCK_STREAM, IPPROTO_TCP, kCFSocketDataCallBack, AcceptDataCallback, &context); memset(&sin, 0, sizeof(sin)); int port = [fieldPorta.text intValue]; NSString *tempIp = fieldIndirizzo.text; const char *ip = [tempIp UTF8String]; sin.sin_family = AF_INET; sin.sin_port = htons(port); sin.sin_addr.s_addr = (long)inet_addr(ip); address = CFDataCreate(NULL, (UInt8 *)&sin, sizeof(sin)); errore = CFSocketConnectToAddress(s, address, 0); if(errore == 0){ buttonInvioMess.enabled = TRUE; fieldMessaggioInvio.enabled = TRUE; labelTemp.text = [NSString stringWithFormat:@"Connesso al Server"]; CFRelease(address); source = CFSocketCreateRunLoopSource(NULL, s, 0); CFRunLoopAddSource(CFRunLoopGetCurrent(), source, kCFRunLoopDefaultMode); CFRelease(source); CFRunLoopRun(); } else{ labelTemp.text = [NSString stringWithFormat:@"Errore di connessione. Verificare Ip e Porta"]; switchConnection.on = FALSE; } } //the socket doesn't disconnect -(void)Disconnetti{ CFSocketInvalidate(s); CFRelease(s); } -(IBAction)Connetti { if(switchConnection.on) [self CreaConnessione]; else [self Disconnetti]; }

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  • MySQL app with Cassandra in mind

    - by SODA
    I am planning to make a web app which will eventually use Cassandra. But now that I don't have it and don't have server(s) to run it from, I'd like to start by using MySQL. The question is, is it possible to structure data and queries in such a way that it would be fairly easy to later port it to Cassandra? Main idea, I guess, would be writing MySQL queries that would be possible to change to same Cassandra queries. Maybe you have a better suggestion?

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  • Gnuplot - splot matrix csv data

    - by Jakub Czaplicki
    How can I plot (a 3D plot) a matrix in Gnuplot having such data structure. I cannot find a way to use the first row and column as a x and y ticks (or to ignore them) ,5,6,7,8 1,-6.20,-6.35,-6.59,-6.02 2,-6.39,-6.52,-6.31,-6.00 3,-6.36,-6.48,-6.15,-5.90 4,-5.79,-5.91,-5.87,-5.46 Is the splot 'data.csv' matrix the correct parameter to use ?

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  • Where to store application global variable?

    - by Shawn Mclean
    I'm using silverlight, project structure is similiar to any other .net app. I have a map control that I would like to store what mode it is in (either road or aerial) so that other controls can access this. Where do I put this enum variable, I plan to use 2 way binding on it so both are updated when either changes. Thanks.

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  • Supersede users need to press enter after inputting a string in python 3.0

    - by Cimex
    I've been attempting to create a simple Rock, Paper, Scissors game in python 3.0 -- very standard task for anybody learning programming. But, as I finish up to a point, I think,"wow, that'd be awesome", or,"it'd be cool to do this!" So anyways, I keep building upon the project... I've developed a menu, a single player game vs the computer, and just finished the multiplayer game. But, I've realized, that the multiplayer game isn't very effective. It just dosen't work like the analog version of the game. Currently, it'll ask for player1's input, then player2's input, compare them, and spit out the result and the current score. What I'd rather have happen is that the program asks for both players input at the same time and both players input their choice at the same time. I understand that I can easily do that by just grabbing the index of the first and second answer and compare the 2 inputs -- easy. But what I'd rather have happen is that after both players enter their one character answers at the same time (r for rock, p for paper, or s for scissors), then the program will auto enter the input. Not needing someone to press enter. The input would be dictated by the fact that 2 characters have been entered. I guess my question is: Is there any way to dictate what can be used as an input for 'enter'?

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  • Finding character in String in Vector.

    - by SoulBeaver
    Judging from the title, I kinda did my program in a fairly complicated way. BUT! I might as well ask anyway xD This is a simple program I did in response to question 3-3 of Accelerated C++, which is an awesome book in my opinion. I created a vector: vector<string> countEm; That accepts all valid strings. Therefore, I have a vector that contains elements of strings. Next, I created a function int toLowerWords( vector<string> &vec ) { for( int loop = 0; loop < vec.size(); loop++ ) transform( vec[loop].begin(), vec[loop].end(), vec[loop].begin(), ::tolower ); that splits the input into all lowercase characters for easier counting. So far, so good. I created a third and final function to actually count the words, and that's where I'm stuck. int counter( vector<string> &vec ) { for( int loop = 0; loop < vec.size(); loop++ ) for( int secLoop = 0; secLoop < vec[loop].size(); secLoop++ ) { if( vec[loop][secLoop] == ' ' ) That just looks ridiculous. Using a two-dimensional array to call on the characters of the vector until I find a space. Ridiculous. I don't believe that this is an elegant or even viable solution. If it was a viable solution, I would then backtrack from the space and copy all characters I've found in a separate vector and count those. My question then is. How can I dissect a vector of strings into separate words so that I can actually count them? I thought about using strchr, but it didn't give me any epiphanies.

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  • Flex unit testing with ANT vs Flash Builder 4

    - by peterlindstrom21
    I have just tried setup unit testing in Flash Builder 4, and it working nicely. A setup of a parallel test source structure and using Flash Builder 4:s new TestCase and new TestSuite I was up and running with some testcases within minutes. But now I want to compile them from a ant flex task, the Flash Builder generates FlexUnitApplication.mxml and FlexUnitCompilerApplication.mxml. Is there a nice way to build the unit tests with ant using these? I cant find any sample where this is done.

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  • How do I make this nested for loop, testing sums of cubes, more efficient?

    - by Brian J. Fink
    I'm trying to iterate through all the combinations of pairs of positive long integers in Java and testing the sum of their cubes to discover if it's a Fibonacci number. I'm currently doing this by using the value of the outer loop variable as the inner loop's upper limit, with the effect being that the outer loop runs a little slower each time. Initially it appeared to run very quickly--I was up to 10 digits within minutes. But now after 2 full days of continuous execution, I'm only somewhere in the middle range of 15 digits. At this rate it may end up taking a whole year just to finish running this program. The code for the program is below: import java.lang.*; import java.math.*; public class FindFib { public static void main(String args[]) { long uLimit=9223372036854775807L; //long maximum value BigDecimal PHI=new BigDecimal(1D+Math.sqrt(5D)/2D); //Golden Ratio for(long a=1;a<=uLimit;a++) //Outer Loop, 1 to maximum for(long b=1;b<=a;b++) //Inner Loop, 1 to current outer { //Cube the numbers and add BigDecimal c=BigDecimal.valueOf(a).pow(3).add(BigDecimal.valueOf(b).pow(3)); System.out.print(c+" "); //Output result //Upper and lower limits of interval for Mobius test: [c*PHI-1/c,c*PHI+1/c] BigDecimal d=c.multiply(PHI).subtract(BigDecimal.ONE.divide(c,BigDecimal.ROUND_HALF_UP)), e=c.multiply(PHI).add(BigDecimal.ONE.divide(c,BigDecimal.ROUND_HALF_UP)); //Mobius test: if integer in interval (floor values unequal) Fibonacci number! if (d.toBigInteger().compareTo(e.toBigInteger())!=0) System.out.println(); //Line feed else System.out.print("\r"); //Carriage return instead } //Display final message System.out.println("\rDone. "); } } Now the use of BigDecimal and BigInteger was delibrate; I need them to get the necessary precision. Is there anything other than my variable types that I could change to gain better efficiency?

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  • Directory.Move doesn't work (file already exist)

    - by phenevo
    I've got main folder: c:\test And there I have 2 folders: Movies and Photos. Photos has three folders with files with the same structure: People, Animals and Buildings. I'm trying this code: Directory.Move(@"c:\test\Movies", @"c:\test\Test"); I get exception: File already exists

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  • How to detect changing directory size in Perl

    - by materiamage
    Hello, I am trying to find a way of monitoring directories in Perl, in particular the size of a directory, and upon detecting a change in directory size, perform a particular action. The issue I have is with large files that require a noticeable amount of time to copy into this directory, i.e. 100MB. What happens (in Windows, not Unix) is the system reserves enough disk space for the entire file, even though the file is still copying in progress. This causes problems for me, because my script will try to perform an action on this file that has not finished copying over. I can easily detect directory size changes in Unix via 'du', but 'du' in Windows does not behave the same way. Are there any accurate methods of detecting directory size changes in Perl? Edit: Some points to clarify: - My Perl script is only monitoring a particular directory, and upon detecting a new file or a new directory, perform an action on this new file or directory. It is not copying any files; users on the network will be copying files into the directory I am monitoring. - The problem occurs when a new file or directory appears (copied, not moved) that is significantly large ( 100MB, but usually a couple GB) and my program fires before this copy completes - In Unix I can easily 'du' to see that the file/directory in question is growing in size, and take the appropriate action - In Windows the size is static, so I cannot detect this change - opendir/readdir/closedir is not feasible, as some of the directories that appear may contain thousands of files, and I want to avoid the overhead of Ideally I would like my program to be triggered on change, but I am not sure how to do this. As of right now it busy waits until it detects a change. The change in file/directory size is not in my control.

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  • Rails MVC Best Practices for Website Modules

    - by Randuin
    I am just beginning to build my Rails application and thus far I've followed a RESTful design and it's proven much easier to understand and organize the code and structure of the application. I have things like posts and comments. However for the front page. I want to display all the latest posts but also may be in the sidebar display things such as Latest Comments and Latest events. What's the best way to go about this while maintaining the RESTful philosophy?

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  • Difference between float and double

    - by VaioIsBorn
    I know, i've read about the difference between double precision and single precision etc. But they should give the same results on most cases right ? I was solving a problem on a programming contest and there were calculations with floating point numbers that were not really big so i decided to use float instead of double, and i checked it - i was getting the correct results. But when i send the solution, it said only 1 of 10 tests was correct. I checked again and again, until i found that using float is not the same using double. I put double for the calculations and double for the output, and the program gave the SAME results, but this time it passed all the 10 tests correctly. I repeat, the output was the SAME, the results were the SAME, but putting float didn't work - only double. The values were not so big too, and the program gave the same results on the same tests both with float and double, but the online judge accepted only the double-provided solution. Why ? What is the difference ?

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  • How to produce 64 bit masks?

    - by egiakoum1984
    Based on the following simple program the bitwise left shit operator works only for 32 bits. Is it true? #include <iostream> #include <stdlib.h> using namespace std; int main(void) { long long currentTrafficTypeValueDec; int input; cout << "Enter input:" << endl; cin >> input; currentTrafficTypeValueDec = 1 << (input - 1); cout << currentTrafficTypeValueDec << endl; cout << (1 << (input - 1)) << endl; return 0; } The output of the program: Enter input: 30 536870912 536870912 Enter input: 62 536870912 536870912 How could I produce 64-bit masks?

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  • Skipping the BufferedReader readLine() method in java

    - by DDP
    Is there a easy way to skip the readLine() method in java if it takes longer than, say, 2 seconds? Here's the context in which I'm asking this question: public void run() { boolean looping = true; while(looping) { for(int x = 0; x<clientList.size(); x++) { try { Comm s = clientList.get(x); String str = s.recieve(); // code that does something based on the string in the line above } // other stuff like catch methods } } } Comm is a class I wrote, and the receive method, which contains a BufferedReader called "in", is this: public String recieve() { try { if(active) return in.readLine(); } catch(Exception e) { System.out.println("Comm Error 2: "+e); } return ""; } I've noticed that the program stops and waits for the input stream to have something to read before continuing. Which is bad, because I need the program to keep looping (as it loops, it goes to all the other clients and asks for input). Is there a way to skip the readLine() process if there's nothing to read? I'm also pretty sure that I'm not explaining this well, so please ask me questions if I'm being confusing.

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  • C system calls open / read / write / close problem.

    - by Andrei Ciobanu
    Hello, given the following code (it's supposed to write "hellowolrd" in a "helloworld" file, and then read the text): #include <fcntl.h> #include <sys/types.h> #include <sys/stat.h> #define FNAME "helloworld" int main(){ int filedes, nbytes; char buf[128]; /* Creates a file */ if((filedes=open(FNAME, O_CREAT | O_EXCL | O_WRONLY | O_APPEND, S_IRUSR | S_IWUSR)) == -1){ write(2, "Error1\n", 7); } /* Writes hellow world to file */ if(write(filedes, FNAME, 10) != 10) write(2, "Error2\n", 7); /* Close file */ close(filedes); if((filedes = open(FNAME, O_RDONLY))==-1) write(2, "Error3\n", 7); /* Prints file contents on screen */ if((nbytes=read(filedes, buf, 128)) == -1) write(2, "Error4\n", 7); if(write(1, buf, nbytes) != nbytes) write(2, "Error5\n", 7); /* Close rile afte read */ close(filedes); return (0); } The first time i run the program, the output is: helloworld After that every time I to run the program, the output is: Error1 Error2 helloworld I don't understand why the text isn't appended, as I've specified the O_APPEND file. Is it because I've included O_CREAT ? It the file is already created, shouldn't O_CREAT be ignored ?

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  • Django choking oddly on some static media

    - by Edan Maor
    My situation: I'm serving static media via Django on my dev machine. On some files that I try and load, I get back this error: Traceback: File "c:\Program Files\Python26\Lib\site-packages\django\core\handlers\base.py" in get_response 92. response = callback(request, *callback_args, **callback_kwargs) File "E:\Stack2Blog\src.hg\stack2blog\..\stack2blog\stack2blogapp\views.py" in userpage 71. so_user = site.user(userid) File "E:\Stack2Blog\src.hg\stack2blog\..\stack2blog\stack2blogapp\stackexchange.py" in user 476. u, = self.users((nid,), **kw) File "E:\Stack2Blog\src.hg\stack2blog\..\stack2blog\stack2blogapp\stackexchange.py" in users 481. return self._get(User, ids, 'users', kw) File "E:\Stack2Blog\src.hg\stack2blog\..\stack2blog\stack2blogapp\stackexchange.py" in _get 471. return self.build(root, typ, coll, kw) File "E:\Stack2Blog\src.hg\stack2blog\..\stack2blog\stack2blogapp\stackexchange.py" in build 448. json = self._request(url, kw) File "E:\Stack2Blog\src.hg\stack2blog\..\stack2blog\stack2blogapp\stackexchange.py" in _request 422. dump = json.load(data) File "c:\Program Files\Python26\lib\json\__init__.py" in load 264. return loads(fp.read(), Exception Type: AttributeError at /userpage/362498 Exception Value: 'str' object has no attribute 'read' I've traced it to specific files which don't work (by going to their specific urls). Here's the odd part: changing the filename of the files makes them suddenly work. For example, I had a file called 'post.jpg', which gave this error. I renamed it to 'pos.jpg' and it worked. Back to 'post.jpg' and it gives the same error.

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  • C++ destructors causing crash's

    - by larsonator
    ok, so i got a some what intricate program that simulates the uni systems of students, units, and students enrolling in units. Students are stored in a binary search tree, Units are stored in a standard list. Student has a list of Unit Pointers, to store which units he/she is enrolled in Unit has a list of Student pointers, to store students which are enrolled in that unit. The unit collections (storing units in a list) as made as a static variable where the main function is, as is the Binary search tree of students. when its finaly time to close the program, i call the destructors of each. but at some stage, during the destructors on the unit side, Unhandled exception at 0x002e4200 in ClassAllocation.exe: 0xC0000005: Access violation reading location 0x00000000. UnitCollection destructor: UnitCol::~UnitCol() { list<Unit>::iterator itr; for(itr = UnitCollection.begin(); itr != UnitCollection.end();) { UnitCollection.pop_front(); itr = UnitCollection.begin(); } } Unit Destructor Unit::~Unit() { } now i got the same sorta problem on the student side of things BST destructors void StudentCol::Destructor(const BTreeNode * r) { if(r!= 0) { Destructor(r->getLChild()); Destructor(r->getRChild()); delete r; } } StudentCol::~StudentCol() { Destructor(root); } Student Destructor Student::~Student() { } so yeah any help would be greatly appreciated

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