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  • tool to find out distance in terms of no. of hops in unix

    - by mawia
    Hi! all, I am writing an application for video streaming.In the application server is required to know the distance of the client from it self in terms of hop number.My question is,is there any tool/method other than traceroute available in unix environment to find it? I also need to find out the geographical location of the client.So is their any tool/method for this as well? Any help in this regard will be highly appreciated. Thanks in advance. Mawia

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  • Having trouble getting GET variables from url.

    - by mchl
    Hey everyone, I'm having trouble with this algorithm to extract the get variables from a url and print them each on a new line like: x=y z=hello etc. but instead it prints a seemingly random section of the url with no newlines to the file. There must be a logic error of some kind but i just can't spot it. for(i_m=0;i_m<len_m;i_m++) { if(var_m[i_m]=='&') { fwrite(var_m+offset_m, 1, amp_m, echo_out); fputc('\n',echo_out); offset_m+=amp_m; amp_m=0; } amp_m++; } any help appreciated.

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  • Cartesian Plane

    - by NuNu
    I'm trying to define a function in Haskell that takes an integer argument c and returns the list of all points on the cartesian plane of the form (x/c,y/c) where x and y are integers. x/c is between -2 and 1 and y/r is between -1 and 1 This is what I've gotten so far which I'm almost sure is right but I'm getting a parse error on input = when I run it particularly at this line: cart xs ys c = [(y/c,x/c) | x <- xs, y <- ys] plane :: Int -> [a] plane c = cart [-1*c .. 1*c] [-2*c .. 1*c] c cart xs ys c = [(y/c,x/c) | x <- xs, y <- ys] A sample output would be: plane 1 would generate: [(-2.0, -1.0), (-1.0, -1.0), ( 0.0, -1.0), ( 1.0, -1.0), (-2.0, 0.0), (-1.0, 0.0), ( 0.0, 0.0), ( 1.0, 0.0), (-2.0, 1.0), (-1.0, 1.0), ( 0.0, 1.0), ( 1.0, 1.0)] Anyone have any idea how I can fix this! Thanks

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  • Wake up thread blocked on accept() call

    - by selbie
    Sockets on Linux question I have a worker thread that is blocked on an accept() call. It simply waits for an incoming network connection, handles it, and then returns to listening for the next connection. When it is time for the program to exit, how do I signal this network worker thread (from the main thread) to return from the accept() call while still being able to gracefully exit its loop and handle it's cleanup code. Some things I tried: 1. pthread_kill to send a signal. Feels kludgy to do this, plus it doesn't reliably allow the thread to do it's shutdown logic. Also makes the program terminate as well. I'd like to avoid signals if at all possible. pthread_cancel. Same as above. It's a harsh kill on the thread. That, and the thread may be doing something else. Closing the listen socket from the main thread in order to make accept() abort. This doesn't reliably work. Some constraints: If the solution involves making the listen socket non-blocking, that is fine. But I don't want to accept a solution that involves the thread waking up via a select call every few seconds to check the exit condition. The thread condition to exit may not be tied to the process exiting. Essentially, the logic I am going for looks like this. void* WorkerThread(void* args) { DoSomeImportantInitialization(); // initialize listen socket and some thread specific stuff while (HasExitConditionBeenSet()==false) { listensize = sizeof(listenaddr); int sock = accept(listensocket, &listenaddr, &listensize); // check if exit condition has been set using thread safe semantics if (HasExitConditionBeenSet()) { break; } if (sock < 0) { printf("accept returned %d (errno==%d)\n", sock, errno); } else { HandleNewNetworkCondition(sock, &listenaddr); } } DoSomeImportantCleanup(); // close listen socket, close connections, cleanup etc.. return NULL; } void SignalHandler(int sig) { printf("Caught CTRL-C\n"); } void NotifyWorkerThreadToExit(pthread_t thread_handle) { // signal thread to exit } int main() { void* ptr_ret= NULL; pthread_t workerthread_handle = 0; pthread_create(&workerthread, NULL, WorkerThread, NULL); signal(SIGINT, SignalHandler); sleep((unsigned int)-1); // sleep until the user hits ctrl-c printf("Returned from sleep call...\n"); SetThreadExitCondition(); // sets global variable with barrier that worker thread checks on // this is the function I'm stalled on writing NotifyWorkerThreadToExit(workerthread_handle); // wait for thread to exit cleanly pthread_join(workerthread_handle, &ptr_ret); DoProcessCleanupStuff(); }

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  • Abort early in a fold

    - by Heptic
    What's the best way to terminate a fold early? As a simplified example, imagine I want to sum up the numbers in an Iterable, but if I encounter something I'm not expecting (say an odd number) I might want to terminate. This is a first approximation def sumEvenNumbers(nums: Iterable[Int]): Option[Int] = { nums.foldLeft (Some(0): Option[Int]) { case (None, _) => None case (Some(s), n) if n % 2 == 0 => Some(s + n) case (Some(_), _) => None } } However, this solution is pretty ugly (as in, if I did a .foreach and a return -- it'd be much cleaner and clearer) and worst of all, it traverses the entire iterable even if it encounters a non-even number. So what would be the best way to write a fold like this, that terminates early? Should I just go and write this recursively, or is there a more accepted way?

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  • What will be the OOP approach? (or YOUR approach?)

    - by hsmit
    I'm having difficulties with some general OOP & Java approach. There are various ways to let classes/objects communicate with each other. To give a simple example: I need object A to perform action X. Object A needs P, Q and R to perform this action X. Will then Object A retrieve P, Q and R by itself (within action X), or must these values be parameters for action X?

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  • what is main focus for a developer when coding?

    - by ajsie
    i read a lot of books about how to code right and usually the are talking about all these techniques from a point of view i can't understand. eg. lets consider the singleton pattern. i'm restricting so the class can only be instantiated once. but since it's only me creating the application, if i know that the class only should be instantiated once, then why would i create it a second time? i feel like missing the big picture. what is my main goal when coding an application? how should i think? thanks

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  • how to access child instances in a vector in c++

    - by tsubasa
    I have a parent class and child class (inherited from parent). In the child class, I have a member function named function_blah(); I used vector<parent*> A to store 5 parent instances, 3 child instances. So the total number of elements in the vector is 8. I can easily access to member functions of element A[0] to A[4], which are parent instances. But whenever I try to have access to member functions of element A[5] to A[7], the compiler complains that class parent has no member named 'function_blah' The way I access to elements is using index. e.x A[i] with i = 0..7. Is it correct? if not, how?

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  • What to Learn after C++?

    - by Stephen Whitmore
    I have been learning C++ for a while now, I find it very powerful. But, the problem is the the level of abstraction is not much and I have to do memory management myself. What are the languages that I can use which uses a higher level of abstraction.

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  • wireless networks c program

    - by Nave
    i wud like to create a wireless network from a laptop. if some laptops come within this range, i wud like to send them a welcome message and when they leave the wifi range, i send them a bye message. is it possible to code such a thing in C? please help me out with this.

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  • Why does Ordered[A] use a compare method instead of reusing compareTo?

    - by soc
    trait Ordered[A] extends java.lang.Comparable[A] { def compare(that: A): Int def < (that: A): Boolean = (this compare that) < 0 def > (that: A): Boolean = (this compare that) > 0 def <= (that: A): Boolean = (this compare that) <= 0 def >= (that: A): Boolean = (this compare that) >= 0 def compareTo(that: A): Int = compare(that) } Isn't it a bit useless to have both compare and compareTo? What is the huge benefit I'm missing here? If they had just used compareTo I could just had replaced Comparable with Ordered in my code and be done.

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  • Using enum values to represent binary operators (or functions)

    - by Bears will eat you
    I'm looking for an elegant way to use values in a Java enum to represent operations or functions. My guess is, since this is Java, there just isn't going to be a nice way to do it, but here goes anyway. My enum looks something like this: public enum Operator { LT, LTEQ, EQEQ, GT, GTEQ, NEQ; ... } where LT means < (less than), LTEQ means <= (less than or equal to), etc - you get the idea. Now I want to actually use these enum values to apply an operator. I know I could do this just using a whole bunch of if-statements, but that's the ugly, OO way, e.g.: int a = ..., b = ...; Operator foo = ...; // one of the enum values if (foo == Operator.LT) { return a < b; } else if (foo == Operator.LTEQ) { return a <= b; } else if ... // etc What I'd like to be able to do is cut out this structure and use some sort of first-class function or even polymorphism, but I'm not really sure how. Something like: int a = ..., b = ...; Operator foo = ...; return foo.apply(a, b); or even int a = ..., b = ...; Operator foo = ...; return a foo.convertToOperator() b; But as far as I've seen, I don't think it's possible to return an operator or function (at least, not without using some 3rd-party library). Any suggestions?

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  • error in script

    - by lego69
    can somebody please help, I'm working with C-Shell, I'm trying to run this script set callsTo = "`cut -d" " -f2 ${1}`" echo $callsTo cut receives data from the file which is the first parameter > ./myscript data I need only second field from every row -f2 after that I want to check if the data was stored, but I receive or an error unmatched `. or empty row, what is wrong with my script, thanks in advance for any help

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  • How can i get more than one jpg. or txt file from any folder?

    - by Phsika
    Dear Sirs; i have two Application to listen network Stream : Server.cs on the other hand; send file Client.cs. But i want to send more files on a stream from any folder. For example. i have C:/folder whish has got 3 jpg files. My client must run. Also My server.cs get files on stream: Client.cs: private void btn_send2_Click(object sender, EventArgs e) { string[] paths= null; paths= System.IO.Directory.GetFiles(@"C:\folder" + @"\", "*.jpg", System.IO.SearchOption.AllDirectories); byte[] Dizi; TcpClient Gonder = new TcpClient("127.0.0.1", 51124); FileStream Dosya; FileInfo Dos; NetworkStream Akis; foreach (string path in paths) { Dosya = new FileStream(path , FileMode.OpenOrCreate); Dos = new FileInfo(path ); Dizi = new byte[(int)Dos.Length]; Dosya.Read(Dizi, 0, (int)Dos.Length); Akis = Gonder.GetStream(); Akis.Write(Dizi, 0, (int)Dosya.Length); Gonder.Close(); Akis.Flush(); Dosya.Close(); } } Also i have Server.cs void Dinle() { TcpListener server = null; try { Int32 port = 51124; IPAddress localAddr = IPAddress.Parse("127.0.0.1"); server = new TcpListener(localAddr, port); server.Start(); Byte[] bytes = new Byte[1024 * 250000]; // string ReceivedPath = "C:/recieved"; while (true) { MessageBox.Show("Waiting for a connection... "); TcpClient client = server.AcceptTcpClient(); MessageBox.Show("Connected!"); NetworkStream stream = client.GetStream(); if (stream.CanRead) { saveFileDialog1.ShowDialog(); // burasi degisecek string pathfolder = saveFileDialog1.FileName; StreamWriter yaz = new StreamWriter(pathfolder); string satir; StreamReader oku = new StreamReader(stream); while ((satir = oku.ReadLine()) != null) { satir = satir + (char)13 + (char)10; yaz.WriteLine(satir); } oku.Close(); yaz.Close(); client.Close(); } } } catch (SocketException e) { Console.WriteLine("SocketException: {0}", e); } finally { // Stop listening for new clients. server.Stop(); } Console.WriteLine("\nHit enter to continue..."); Console.Read(); } Please look Client.cs: icollected all files from "c:\folder" paths= System.IO.Directory.GetFiles(@"C:\folder" + @"\", "*.jpg", System.IO.SearchOption.AllDirectories); My Server.cs how to get all files from stream?

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  • How to deal with a coworker who keeps asking instead of searching herself?

    - by mafutrct
    I'm lucky enough to share a room with 3 other people at work. One of them, a senior programmer who's very talkative in general, tends to ask me various questions throughout the day. While some of them are surely ' legitimate', many questions could have been answered by putting in just slightly more search effort on their part. I really don't mind be asked stuff, and I can also cope with beginner questions, but this is seriously interrupting my flow. I clearly remember Joel talking about how private offices increase productivity because they prevent too easy questions from being asked. How should I deal with this situation? Getting a private office is out of the question, sadly. It's difficult to approach him directly, and he blissfully ignored the slight hints I tried to give.

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  • What is the fastest language? [closed]

    - by Murtez
    I'm looking to make a site with a database, user accounts, and possibly more later on (subscriptions, bidding, payment, any any possible # of upgrades). Website speed is VERY important, what is the fastest secure language / method to make it in?

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  • Heap Algorithmic Issue

    - by OberynMarDELL
    I am having this algorithmic problem that I want to discuss about. Its not about find a solution but about optimization in terms of runtime. So here it is: Suppose we have a race court of Length L and a total of N cars that participate on the race. The race rules are simple. Once a car overtakes an other car the second car is eliminated from the race. The race ends when no more overtakes are possible to happen. The tricky part is that the k'th car has a starting point x[k] and a velocity v[k]. The points are given in an ascending order, but the velocities may differ. What I've done so far: Given that a car can get overtaken only by its previous, I calculated the time that it takes for each car to reach its next one t = (x[i] - x[i+1])/(v[i] - v[i+1]) and I insert these times onto a min heap in O(n log n). So in theory I have to pop the first element in O(logn), find its previous, pop it as well , update its time and insert it in the heap once more, much like a priority queue. My main problem is how I can access specific points of a heap in O(log n) or faster in order to keep the complexity in O(n log n) levels. This program should be written on Haskell so I would like to keep things simple as far as possible EDIT: I Forgot to write the actual point of the race. The goal is to find the order in which cars exit the game

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  • Testing for a closed socket

    - by Robert S. Barnes
    I'm trying to test for a closed socket that has been gracefully closed by the peer without incurring the latency hit of a double send to induce a SIGPIPE. One of the assumptions here is that the socket if closed was gracefully closed by the peer immediately after it's last write / send. Actual errors like a premature close are dealt with else where in the code. If the socket is still open, there will be 0 or more bytes data which I don't actually want to pull out of the socket buffer yet. I was thinking that I could call int ret = recv(sockfd, buf, 1, MSG_DONTWAIT | MSG_PEEK); to determine if the socket is still connected. If it's connected but there's no data in the buffer I'll get a return of -1 with errno == EAGAIN and return the sockfd for reuse. If it's been gracefully closed by the peer I'll get ret == 0 and open a new connection. I've tested this and it seems to work. However, I suspect there is a small window between when I recv the last bit of my data and when the peer FIN arrives in which I could get a false-positive EAGAIN from my test recv. Is this going to bite me, or is there a better way of doing this?

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