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  • General advice from people in the industry - new graduate

    - by confusified
    I'm 20 years old and have just finished a 4 year Information Technology degree in Ireland, The main focus of the course was programming (mainly java) and software engineering. My question (posted in the wrong place as it may be) is : What technologies that I may not have studied should I attempt to teach myself that will be of the most benefit to me in searching for employment? All input appreciated.

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  • Can I use WCF NET.TCP Protocol from Silverlight 4 for a public website ?

    - by pixel3cs
    Does anyone know if the new NET.TCP feature of Silverlight 4 can be used for public websites ? From what I know, in the Silverlight 4 Beta they announced that WCF NET.TCP can only be used for intranet applications. The reason I am asking this is because I want to recode my Silverlight multiplayer chess game (build with SL 3 Sockets support) based on the new SL 4 WCF TCP communication protocol. My Socket implementation is build from scratch and have big issues with thread safe and few unsolvable bugs from my side. I am sure that SL 4 team did a great job and they simplified all hard part for me, letting us, developers, concentrate more on the game code instead on underlying communication layers.

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  • How much memory is reserved when i declare a string?

    - by Bhagya
    What exactly happens, in terms of memory, when i declare something like: char arr[4]; How many bytes are reserved for arr? How is null string accommodated when I 'strcpy' a string of length 4 in arr? I was writing a socket program, and when I tried to suffix NULL at arr[4] (i.e. the 5th memory location), I ended up replacing the values of some other variables of the program (overflow) and got into a big time mess. Any descriptions of how compilers (gcc is what I used) manage memory?

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  • Is multithreading the right way to go for my case?

    - by Julien Lebosquain
    Hello, I'm currently designing a multi-client / server application. I'm using plain good old sockets because WCF or similar technology is not what I need. Let me explain: it isn't the classical case of a client simply calling a service; all clients can 'interact' with each other by sending a packet to the server, which will then do some action, and possible re-dispatch an answer message to one or more clients. Although doable with WCF, the application will get pretty complex with hundreds of different messages. For each connected client, I'm of course using asynchronous methods to send and receive bytes. I've got the messages fully working, everything's fine. Except that for each line of code I'm writing, my head just burns because of multithreading issues. Since there could be around 200 clients connected at the same time, I chose to go the fully multithreaded way: each received message on a socket is immediately processed on the thread pool thread it was received, not on a single consumer thread. Since each client can interact with other clients, and indirectly with shared objects on the server, I must protect almost every object that is mutable. I first went with a ReaderWriterLockSlim for each resource that must be protected, but quickly noticed that there are more writes overall than reads in the server application, and switched to the well-known Monitor to simplify the code. So far, so good. Each resource is protected, I have helper classes that I must use to get a lock and its protected resource, so I can't use an object without getting a lock. Moreover, each client has its own lock that is entered as soon as a packet is received from its socket. It's done to prevent other clients from making changes to the state of this client while it has some messages being processed, which is something that will happen frequently. Now, I don't just need to protect resources from concurrent accesses. I must keep every client in sync with the server for some collections I have. One tricky part that I'm currently struggling with is the following: I have a collection of clients. Each client has its own unique ID. When a client connects, it must receive the IDs of every connected client, and each one of them must be notified of the newcomer's ID. When a client disconnects, every other client must know it so that its ID is no longer valid for them. Every client must always have, at a given time, the same clients collection as the server so that I can assume that everybody knows everybody. This way if I'm sending a message to client #1 telling "Client #2 has done something", I know that it will always be correctly interpreted: Client 1 will never wonder "but who is Client 2 anyway?". My first attempt for handling the connection of a new client (let's call it X) was this pseudo-code (remember that newClient is already locked here): lock (clients) { foreach (var client in clients) { lock (client) { client.Send("newClient with id X has connected"); } } clients.Add(newClient); newClient.Send("the list of other clients"); } Now imagine that in the same time, another client has sent a packet that translates into a message that must be broadcasted to every connected client, the pseudo-code will be something like this (remember that the current client - let's call it Y - is already locked here): lock (clients) { foreach (var client in clients) { lock (client) { client.Send("something"); } } } An obvious deadlock occurs here: on one thread X is locked, the clients lock has been entered, started looping through the clients, and at one moment must get Y's lock... which is already acquired on the second thread, itself waiting for the clients collection lock to be released! This is not the only case like this in the server application. There are other collections which must be kept in sync with the clients, some properties on a client can be changed by another one, etc. I tried other types of locks, lock-free mechanisms and a bunch of other things. Either there were obvious deadlocks when I'm using too much locks for safety, or obvious race conditions otherwise. When I finally find a good middle point between the two, it usually comes with very subtle race conditions / dead locks and other multi-threading issues... my head hurts very quickly since for any single line of code I'm writing I have to review almost the whole application to ensure everything will behave correctly with any number of threads. So here's my final question: how would you resolve this specific case, the general case, and more importantly: aren't I going the wrong way here? I have little problems with the .NET framework, C#, simple concurrency or algorithms in general. Still, I'm lost here. I know I could use only one thread processing the incoming requests and everything will be fine. However, that won't scale well at all with more clients... But I'm thinking more and more to go this simple way. What do you think? Thanks in advance to you, StackOverflow people which have taken the time to read this huge question. I really had to explain the whole context if I want to get some help.

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  • Mood for coding

    - by dole doug
    When you don't have the mood for coding, how do you get it? Now I'm working on a project that I don't like at all, besides is a new programming language for me and I have to do it alone. So, the question is: how do you get the mood for coding? Any tips/tricks are welcome :)

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  • Pitfalls when switching to .NET for Windows CE?

    - by Presidenten
    Hi! I have been developing in .NET for quite some time now. But now I have customer who wants me to develop an application for them in .NET for Windows CE. I have done some embedded system programming in C before, but never in .NET. Please share any tips or tricks that would make my life easier when taking this assignment, or perhaps knowledge about any pitfalls to watch out for.

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  • UV-vis detector [Hardware]

    - by aaa
    hello. This is not hundred percent programming related question, but I was not able to find answer on the net. Is there some kind of detector to record frequency/intensity of light radiation source? something like spectroscopy detector, but instead of actual machine, just the module which can be integrated in project. I have tried searching on Google but I do not even know what such device is called if you know the more appropriate place to ask, can you let me know please. Thank you

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  • How do I superimpose one bitmap image on another in GDI+?

    - by Old Man
    Using GDI+ I've made a heatmap bmp and I'd like to superimpose it on top of my bmp map. I've saved the two bmps to disk, and they look good, I just need a way to put them together. Is there any way to do this, perhaps using the Graphics object? How is transparency/alpa involved? I'm very new to GDI programming so please be as specific as possible.

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  • GDI+ Resize Function

    - by Tyler
    So my logic is flawed and I need a better and correct way to resize an image in my c# app I need a function similar to this setup public void ResizeImageForWeb(string OriginalFile, string NewFile, int MaxWidth, int MaxHeight, int Quality) { // Resize Code } Basically, I'm a web designer lost trying to programming a desktop app.

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  • Good C++ Debugging/IDE Environment for Linux?

    - by Brandon Pelfrey
    I have a friend who is trying to make the switch to Linux, but is hung up on the apparent lack of debugging/IDE environments for C++, especially as they relate to template programming. He has been using visual studio for years and is maybe a little spoiled by their awesome IDE. Does anyone have any good suggestions for an environment where he can, under Linux, develop and debug with all of the usual things (Breakpoints, line highlighting for compilation errors, step in/over/out/etc, etc) that he's accustomed to? Thanks!

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  • Does TCP actually define 'TCP server' and 'TCP clients'? [closed]

    - by mjn
    In the Wikipedia article, TCP communication is explained using the terms 'client' and 'server'. It also uses the word 'peers'. But TCP actually does not define "TCP clients" and "TCP servers" - In the RFC 675 document (SPECIFICATION OF INTERNET TRANSMISSION CONTROL PROGRAM), the word "client" never appears. The RFC explains that TCP is used to connect processes over ports (sockets), and that 'A pair of sockets form a CONNECTION which can be used to carry data in either direction [i.e. full duplex]. Calling the originating party the "client" seems to be common practice. But this client/server communication model is not always applicable to TCP communication. For example take peer-to-peer networks. Calling all processes which open a socket (and wait for incoming connections from peers) "TCP servers", sounds wrong to me. I would not call my uncle's telephone device a "Telephony server" if I dial his phone number and he picks up.

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  • void foo(int &x) -> Ruby? Passing integers by reference?

    - by Earlz
    Hello, as a way to spice up my C++ programming homework, I've decided to instead of typing the C++ from the book onto my computer, instead reforming it in Ruby. Yes it's a bit silly, but I'm bored. Anyway, I'm having trouble converting this kind of function to Ruby void swap(int &a,int &b){ int c=b; b=a; a=c } What would the equivalent ruby code looking inside a function ?

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  • What are the list of Patterns and Principals the programmer must/should know?

    - by pang
    I have been doing code for a few years and still feeling that my knowledge still not broad enough to become a professional. I have studied some books related to Design Pattern but I know there are many others. So could anyone list the one which you think it is good to learn to become a better programmer and more professional? Programming Languages I work on : C# , Ruby, Javascript

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  • Webcam capture with c# and convert to avi

    - by Spidfire
    Im trying to make a program that captures a video from the webcam and sound from the microphone but im getting stuck at the part where ive try to make a movie out of still images ive heard you need to use directshow but it doesnt jet work for me Does someone know a good piece of example code that captures video and sound and can encode it to a file (divx or something like that) ? or some suggestions where to look so i can build it myself (if a other programming language is better for this im happy to know it early. )

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  • Where can I find the IRQ number in request_irq function?

    - by sasayins
    Hi, Im learning device driver programming in Linux. And I'm wondering where I could the IRQ number in the request_irq function. int request_irq (unsigned int irq, void (*handler) (int, void *, struct pt_regs *), unsigned long irqflags, const char *devname, void *dev_id); In the irq parameter, what value or where could I find that value to put in the request_irq function? Thanks

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