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  • Network programming on java

    - by maks
    I have written a simple network program on java using sockets. Program has a client and a server. When user types a word on client side, server simply return this word to client. On server side I use Serversocket and bind it to port 4444. Why does not firewall block this connection on my server PC? I ask this question because earlier I wrote this program using corba technology, and firewall on my server PC was blocking the connection to this port; when I disabled the firewall the program worked fine.

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  • A Question about dereferencing pointer to incomplete type In C programming

    - by user552279
    Hi, can you explain this error for me? Blockquote /////////////////////////////// In my A.h file: struct TreeNode; struct TreeHead; typedef struct TreeNode * Node; typedef struct TreeHead * Head; /////////////////////////////// In my A.c file: struct TreeNode { char* theData; Node Left; Node Right; } ; struct TreeHead{ int counter; char type; Node Root; }; Head Initialisation() { Head treeHead; treeHead = malloc(sizeof (struct TreeHead)); treeHead-Root = malloc(sizeof (struct TreeNode)); return treeHead; } /////////////////////////////// In my Main.c file: Head head; Node tree; int choose =5; head = Initialisation(); (head-Root) = tree; //When compiling, this line has an error: error: dereferencing pointer to incomplete type Blockquote haed-Root will return a Node pointer, tree is also a Node pointer. So why error is dereferencing pointer to "incomplete" type?

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  • C programming: hashtable insertion/search

    - by Ricardo Campos
    Hello i have a problem with my hash table its implemented like this: #define HT_SIZE 10 typedef struct _list_t_ { char key[20]; char string[20]; char prevValue[20]; struct _list_t_ *next; } list_t; typedef struct _hash_table_t_ { int size; /* the size of the table */ list_t ***table; /* first */ sem_t lock; } hash_table_t; I have a Linked list with 3 pointers because i want a hash table with several partitions (shards), here is my initialization of my Hash table: hash_table_t *create_hash_table(int NUM_SERVER_THREADS, int num_shards){ hash_table_t *new_table; int j,i; if (HT_SIZE<1) return NULL; /* invalid size for table */ /* Attempt to allocate memory for the hashtable structure */ new_table = (hash_table_t*)malloc(sizeof(hash_table_t)*HT_SIZE); /* Attempt to allocate memory for the table itself */ new_table->table = (list_t ***)calloc(1,sizeof(list_t **)); /* Initialize the elements of the table */ for(j=0; j<num_shards; j++){ new_table->table[j] = (list_t **)calloc(1,sizeof(list_t *)); for(i=0; i<HT_SIZE; i++){ new_table->table[j][i] = (list_t *)calloc(1,sizeof(list_t )); } } /* Set the table's size */ new_table->size = HT_SIZE; sem_init(&new_table->lock, 0, 1); return new_table; } Here is my search function to search in the hash table list_t *lookup_string(hash_table_t *hashtable, char *key, int shardId){ list_t *list ; int hashval = hash(key); /* Go to the correct list based on the hash value and see if key is * in the list. If it is, return return a pointer to the list element. * If it isn't, the item isn't in the table, so return NULL. */ sem_wait(&hashtable->lock); for(list = hashtable->table[shardId][hashval]; list != NULL; list =list->next) { if (strcmp(key, list->key) == 0){ sem_post(&hashtable->lock); return list; } } sem_post(&hashtable->lock); return NULL; } And my insert function: char *add_string(hash_table_t *hashtable, char *str,char *key, int shardId){ list_t *new_list; list_t *current_list; unsigned int hashval = hash(key); /*printf("|%d|%d|%s|\n",hashval,shardId,key);*/ /* Lock for concurrency */ sem_wait(&hashtable->lock); /* Attempt to allocate memory for list */ new_list = (list_t*)malloc(sizeof(list_t)); /* Does item already exist? */ sem_post(&hashtable->lock); current_list = lookup_string(hashtable, key,shardId); sem_wait(&hashtable->lock); /* item already exists, don't insert it again. */ if (current_list != NULL){ strcpy(new_list->prevValue,current_list->string); strcpy(new_list->string,str); strcpy(new_list->key,key); new_list->next = hashtable->table[shardId][hashval]; hashtable->table[shardId][hashval] = new_list; sem_post(&hashtable->lock); return new_list->prevValue; } /* Insert into list */ strcpy(new_list->string,str); strcpy(new_list->key,key); new_list->next = hashtable->table[shardId][hashval]; hashtable->table[shardId][hashval] = new_list; /* Unlock */ sem_post(&hashtable->lock); return new_list->prevValue; } My main class runs some of tests by executing the insertion / reading / delete from the elements of the hash table the problem is when i have more than 4 partitions/shards the tests stop at the first reading element saying it returned the wrong value NULL on the search function, when its less than 4 it runs perfectly well and passes all the tests. You can see my main.c in here if you want to give a look: http://hostcode.sourceforge.net/view/1105 My complete Hash table code: http://hostcode.sourceforge.net/view/1103 And other functions where hash table code is executed: .c file http://hostcode.sourceforge.net/view/1104 .h file http://hostcode.sourceforge.net/view/1106 Thank for you time, i appreciate any help you can give to me this is a college important project that I'm trying to solve and I'm stuck here for 2 days.

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  • Event driven programming in perl?

    - by TheGNUGuy
    Hey everyone, I'm trying to make a jabber bot and I am having trouble keeping it running while waiting for messages. How do I get my script to continuously run? I have tried calling a subroutine that has a while loop that I , in theory, have set up to check for any messages and react accordingly but my script isn't behaving that way. Here is my source: http://pastebin.com/03Habbvh

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  • C Programming - Passing a pointer to array

    - by Pedro
    How do I pass a pointer value to an array of the struct; For example, on a txt I have this: John Doe;[email protected];214425532; My code: typedef struct Person{ char name[100]; char email[100]; int phone; }PERSON; int main(){ PERSON persons[100]; FILE *fp; char *ap_name; char *ap_email; char *ap_phone; char line[100]; fp=("text.txt","r"); if(fp==NULL){ exit(1); } else{ fgets(line,100,fp); ap_name=strtok(line,";"); ap_email=strtok(NULL,";"); ap_phone=strtok(NULL,";"); } return 0; } My question is how can I pass the value of ap_name, ap_email, ap_phone to the struct? And, do I need to use all of these pointers?

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  • Interview Programming Questions - In house Exam

    - by David McGraw
    I have a company that would like to bring me in to serve me an hour long exam. No resources other than a pencil and paper. I really couldn't get any sort of feedback on the type of exam (implementation or generic) beside that it would test a few specific areas. Have you done anything like this? What sort of questions did they ask? What's a good way to prepare? I'll probably go in a couple weeks before school starts back up. A time sensitive exam structure is a weak point for me, so what should I absolutely focus down on? If they like the exam, that's when I'll get a face-to-face meeting. An advance thanks goes to everybody who provide their time.

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  • COM(C++) Programming Tutorials

    - by Deep-B
    Hey guys, I was wondering if there're any good sites that deal with learning C++/COM from the ground up? Looking for something like a crash course (two weeks, and not being hypothetical here). Assume knowledge in standard C/C++, or at least not a complete dummy.

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  • Help with visual programming??

    - by tjk0102
    i'm making a program that i need help with i'm trying to duplicate impero's policy lock screen i need help i'm trying to have my program search to see if a file is there. the concept is if the file exists it will launch it,but i'm having troubles would i use background worker do search for it and if so how would i make it search for it? if you can help that will be great

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  • HTML tags in ojective c programming

    - by user1661826
    Is there any function in Objective-C to print a list of elements as unordered HTML elements. For ex - [@"a--b-c---d" htmlList: @"--"] returns @ "ab-c-d" the "--" is the delimiter to seperate the string of elements. I have used NSSArray to store the input string and function componentsSeperatedByString:@"--" to get the elements. How do I go ahead in adding the HTML tags li and /li between elements and ul and /ul at the end of the entire list? Please help, Im a beginner in objective -C

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  • Programming powering off and powering on in one single OnClick function on android

    - by user1060919
    I would like to write an activity that after clicking on a button turns off the screen and then turns it back on after 2 secs. I tried using the following code in order to power off the screen: WindowManager.LayoutParams lp = getWindow().getAttributes(); lp.screenBrightness = 0/(float)255; getWindow().setAttributes(lp); But it would only take effect when then onClick function returns. I tried running it into a handler but with no success. I need to find a way to force the setting to get applied before the function returns so that I can call the power on function 2 secs later on the same onClick call. I also found it very hard to wakeup the device afterwards. While this code works if I power off the screen using the physical button it doesn't seem to work when the phone is powered off using the technique described previously. PowerManager pm = (PowerManager)this.getSystemService(Context.POWER_SERVICE); PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.FULL_WAKE_LOCK|PowerManager.ACQUIRE_CAUSES_WAKEUP | PowerManager.ON_AFTER_RELEASE ,"Dev Tag"); try { wl.acquire(); wl.release(); } catch (Exception e) { Toast.makeText(this, e.getMessage(),20).show(); } Thanks you in advance for your help!

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  • c++ programming- Tryin to get a number within an array that is twice the average

    - by max
    i have been assigned to set up an array with points. I am told to get the maximum value, average, nd within this same array, if any point in the array is twice the average, i should cout an "outlier." So far i have gotten the average and maximum numbers in the array. but i am unable to set the programme to cout the outlier. Instead it gives me a multiple of the average. pls help! here is the programme; int main() { const int max = 10; int ary[max]={4, 32, 9, 7, 14, 12, 13, 17, 19, 18}; int i,maxv; double out,sum=0; double av; maxv= ary[0]; for(i=0; i } cout<<"maximum value: "< for(i=0; i sum = sum + ary[i]; av = sum / max; } cout<<"average: "< out = av * 2; if(ary[i]out) { cout<<"outlier: "< return 0; }

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  • Programming Windows Cluster resource DLLs using Delphi

    - by kaeff
    I wonder whether there's a way to program a resource DLL for Windows Clusters in Delphi. I want to write a program that observes cluster state changes. Judging from the MSDN API reference, all relevant functions are located in the ClusAPI.h and ResAPI.h headers, but unfortunately it seems as if they haven't been ported yet and HeaderConv seems to fail on them. Does anyone has experience in doing such a thing?

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  • Socket Programming : Inputstream Stuck in loop - read() always return 0

    - by Atom Skaa ska Hic
    Server side code public static boolean sendFile() { int start = Integer.parseInt(startAndEnd[0]) - 1; int end = Integer.parseInt(startAndEnd[1]) - 1; int size = (end - start) + 1; try { bos = new BufferedOutputStream(initSocket.getOutputStream()); bos.write(byteArr,start,size); bos.flush(); bos.close(); initSocket.close(); System.out.println("Send file to : " + initSocket); } catch (IOException e) { System.out.println(e.getLocalizedMessage()); disconnected(); return false; } return true; } Client Side public boolean receiveFile() { int current = 0; try { int bytesRead = bis.read(byteArr,0,byteArr.length); System.out.println("Receive file from : " + client); current = bytesRead; do { bytesRead = bis.read(byteArr, current, (byteArr.length-current)); if(bytesRead >= 0) current += bytesRead; } while(bytesRead != -1); bis.close(); bos.write(byteArr, 0 , current); bos.flush(); bos.close(); } catch (IOException e) { System.out.println(e.getLocalizedMessage()); disconnected(); return false; } return true; } Client side is multithreading,server side not use multithreading. I just paste some code that made problem if you want see all code please tell me. After I debug the code, I found that if I set max thread to any and then the first thread always stuck in this loop. That bis.read(....) always return 0. Although, server had close stream and it not get out of the loop. I don't know why ... But another threads are work correctly. do { bytesRead = bis.read(byteArr, current, (byteArr.length-current)); if(bytesRead >= 0) current += bytesRead; } while(bytesRead != -1);

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  • Socket Programming for the Web

    - by Benny
    I have to interact with a legacy system that accepts socket communication and messages. My goal is to make the application cross-platform, but I need the ability to push messages to the client (i.e. - .NET's WCF, Java's Comet) and detect when the user closes out of their browser to destroy the socket. I have built a prototype of .NET wrapper + WCF + Silverlight but it is so disconnected it is difficult to manage the state of the user and seems to be a nightmare to support. All of that considered, what would be my best option?

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  • programming in lua, objects

    - by anon
    Sample code: function Account:new (o) o = o or {} -- create object if user does not provide one setmetatable(o, self) self.__index = self return o end taken from: http://www.lua.org/pil/16.1.html What is the purpose of the: self.__index = self line? And why is it executed every time an object is created?

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  • 'Good' programming form in maintaining / updating / accessing files by entry

    - by zhermes
    Basic Question: If I'm storying/modifying data, should I access elements of a file by index hard-coded index, i.e. targetFile.getElement(5); via a hardcoded identifier (internally translated into index), i.e. target.getElementWithID("Desired Element"), or with some intermediate DESIRED_ELEMENT = 5; ... target.getElement(DESIRED_ELEMENT), etc. Background: My program (c++) stores data in lots of different 'dataFile's. I also keep a list of all of the data-files in another file---a 'listFile'---which also stores some of each one's properties (see below, but i.e. what it's name is, how many lines of information it has etc.). There is an object which manages the data files and the list file, call it a 'fileKeeper'. The entries of a listFile look something like: filename , contents name , number of lines , some more numbers ... Its definitely possible that I may add / remove fields from this list --- but in general, they'll stay static. Right now, I have a constant string array which holds the identification of each element in each entry, something like: const string fileKeeper::idKeys[] = { "FileName" , "Contents" , "NumLines" ... }; const int fileKeeper::idKeysNum = 6; // 6 - for example I'm trying to manage this stuff in 'good' programatic form. Thus, when I want to retrieve the number of lines in a file (for example), instead of having a method which just retrieves the '3'rd element... Instead I do something like: string desiredID = "NumLines"; int desiredIndex = indexForID(desiredID); string desiredElement = elementForIndex(desiredIndex); where the function indexForID() goes through the entries of idKeys until it finds desiredID then returns the index it corresponds to. And elementForIndex(index) actually goes into the listFile to retrieve the index'th element of the comma-delimited string. Problem: This still seems pretty ugly / poor-form. Is there a way I should be doing this? If not, what are some general ways in which this is usually done? Thanks!

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  • in .net, what programming model would be good for prototyping, but then reusable for production (for

    - by Greg
    Hi, In .NET land what would be a good approach for quick prototyping of a concept (i.e. development just on my PC) that could then be extended out to product (users across LAN/WAN), BUT in a fashion that the model/business logic code and data access layer code can be used as is? One thought for example I had as to do: (a) WinForms with business logic and Entity Framework layer to SQL Server Express on my PC, then (b) Go then to ASP.net (using the business logic / data library) with SQL Server/IIS Any comments? Other suggestions?

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  • Programming CLI Commands in Program [C / LINUX]

    - by Blackbinary
    I am attempting to make a program in C which presents a GUI and allows the user to select from a list of applications, which to install on the computer. I can manage the gui, but I've never been taught how to actually issue command line commands. I know with bash its just apt-get install firefox for example, but how do I do such a thing with C? i.e. on click, the program runs 'apt-get install The other problem is I'm not familiar with the proper name for this interaction, so it is hard to search. Thanks for the help

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