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• In C and C++, what methods can prevent accidental use of the assignment(=) where equivalence(==) is needed?

  - by DeveloperDon

  In C and C++, it is very easy to write the following code with a serious error. char responseChar = getchar(); int confirmExit = 'y' == tolower(responseChar); if (confirmExit = 1) { exit(0); } The error is that the if statement should have been: if (confirmExit == 1) As coded, it will exit every time, because the assignment of the confirmExit variable occurs, then confirmExit is used as the result of the expression. Are there good ways to prevent this kind of error?

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• How to choose between Tell don't Ask and Command Query Separation?

  - by Dakotah North

  The principle Tell Don't Ask says: you should endeavor to tell objects what you want them to do; do not ask them questions about their state, make a decision, and then tell them what to do. The problem is that, as the caller, you should not be making decisions based on the state of the called object that result in you then changing the state of the object. The logic you are implementing is probably the called object’s responsibility, not yours. For you to make decisions outside the object violates its encapsulation. A simple example of "Tell, don't Ask" is Widget w = ...; if (w.getParent() != null) { Panel parent = w.getParent(); parent.remove(w); } and the tell version is ... Widget w = ...; w.removeFromParent(); But what if I need to know the result from the removeFromParent method? My first reaction was just to change the removeFromParent to return a boolean denoting if the parent was removed or not. But then I came across Command Query Separation Pattern which says NOT to do this. It states that every method should either be a command that performs an action, or a query that returns data to the caller, but not both. In other words, asking a question should not change the answer. More formally, methods should return a value only if they are referentially transparent and hence possess no side effects. Are these two really at odds with each other and how do I choose between the two? Do I go with the Pragmatic Programmer or Bertrand Meyer on this?

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• When is it appropriate to use colour in a command-line application?

  - by marcoms

  Currently I have a command-line application in C called btcwatch. It has a -C option that it can receive as an argument that compares the current price of Bitcoin with a price that was stored beforehand with -S. Example output with this option is: $ btcwatch -vC # -v = verbose buy: UP $ 32.000000 USD (100.000000 -> 132.000000) sell: UP $ 16.000000 USD (100.000000 -> 116.000000) The dilemma is whether to use colour for the UP or DOWN string (green and red, respectively). Most command-line applications I know of (apart from git) stay away from colour in their output. In my desire for btcwatch to look and be quite "standard" (use of getopt, Makefiles, etc), I'm not sure if colour would look out of place in this situation.

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• Is sending data to a server via a script tag an outdated paradigm?

  - by KingOfHypocrites

  I inherited some old javascript code for a website tracker that submits data to the server using a script url: var src = "http://domain.zzz/log/method?value1=x&value2=x" var e = document.createElement('script'); e.src = src; I guess the idea was that cross domain requests didn't haven't to be enabled perhaps. Also it was written back in 2005. I'm not sure how well XmlHttpRequests were supported at the time. Anyone could stick this on their website and send data to our server for logging and it ideally would work in most any browser with javascript. The main limitation is all the server can do is send back javascript code and each request has to wait for a response from the server (in the form of a generic acknowledgement javascript method call) to know it was received, then it sends the next. I can't find anyone doing this online or any metrics as to whether this faster or more secure than XmlHttpRequests. I don't know if this is just an old way of doing things or it's still the best way to send data to the server when you are mostly trying to send data one way and you need the best performance possible. So in summary is sending data via a script tag an outdated paradigm? Should I abandon in favor of using XmlHttpRequsts?

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• What is the possible disadvantage of putting declarations in inner blocks, instead of at beginning of function?

  - by shan23

  At the place where I work, there are explicit guidelines for placement of declarations of variables. According to that, it is required to put them at the global level and / or at the beginning of functions, and not in inner blocks (such as a for loop). Since they've been specified by persons more experienced than I am, I'm sure that there must be a good reason for it, but I cannot figure out what that might be. It would be nice to know if there are any compile time / run time advantages at having them declared at a bigger scope.

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• When creating a library for a simple program, what must I do to protect others from its lack of thread safety?

  - by DeveloperDon

  When creating a library for a simple program, is it more cost effective to make it thread safe or is there a way to detect the program's use in a multithreaded program and ASSERT() or otherwise determine (preferably at compile or link time) that it may create problems. Related help for this question would be automated tool support for finding potential problems with thread safety, programming language features that enforce it,

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• Is the use of explicit ' == true' comparison always bad? [closed]

  - by Slomojo

  Possible Duplicate: Make a big deal out of == true? I've been looking at a lot of code samples recently, and I keep noticing the use of... if( expression == true ) // do something... and... x = ( expression == true ) ? x : y; I've tended to always use... x = ( expression ) ? x : y; and... if( expression ) // do something... Where == true is implicit (and obvious?) Is this just a habit of mine, and I'm being picky about the explicit use of == true, or is it simply bad practice?

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• Bikeshedding: Placeholders in strings

  - by dotancohen

  I find that I sometimes use placeholders in strings, like this: $ cat example-apache <VirtualHost *:80> ServerName ##DOMAIN_NAME## ServerAlias www.##DOMAIN_NAME## DocumentRoot /var/www/##DOMAIN_NAME##/public_html </VirtualHost> Now I am sure that it is a minor issue if the placeholder is ##DOMAIN_NAME##, !!DOMAIN_NAME!!, {{DOMAIN_NAME}}, or some other variant. However, I now need to standardize with other developers on a project, and we all have a vested interest in having our own placeholder format made standard in the organization. Are there any good reasons for choosing any of these, or others? I am trying to quantify these considerations: Aesthetics and usability. For example, __dict__ may be hard to read as we don't know how many underscores are in there. Compatibility. Will some language try to do something funny with {} syntax in a string (such as PHP does with "Welcome to {$siteName} today!")? Actually, I know that PHP and Python won't, but others? Will a C++ preprocessor choke on ## format? If I need to store the value in some SQL engine, will it not consider something a comment? Any other pitfalls to be wary of? Maintainability. Will the new guy mistake ##SOME_PLACEHOLDER## as a language construct? The unknown. Surely the wise folk here will think of other aspects of this decision that I have not thought of. I might be bikeshedding this, but if there are real issues that might be lurking then I would certainly like to know about them before mandating that our developers adhere to a potentially-problematic convention.

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• SSD harddisks & programming

  - by Carra

  SSD harddisks have been on the rise lately. And I've been wondering if it's worth buying one as a programmer. Being able to save five minutes when starting my PC is fun but won't convince my boss. How does it impact a typical visual studio project containing hundreds of files? Compile times, accessing files, waiting for visual studio to do its thing... Are there any benchmarks that checked this? And ideally, how much time would one win each week by upgrading?

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• Checking negative of a condition

  - by oym

  What is the (slightly pejorative) term for checking the negative of a condition (rather than the positive which is often more readable): e.g. if(!someVar) { return null; } else { return doSomethingInteresting(); } instead of doing this (which is arguably more readable) if(someVar) { return doSomethingInteresting(); } else { return null; } I vaguely remember there being a term for this; something in the same spirit as the term Yoda conditions.

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• Placeholders in strings

  - by dotancohen

  I find that I sometimes use placeholders in strings, like this: $ cat example-apache <VirtualHost *:80> ServerName ##DOMAIN_NAME## ServerAlias www.##DOMAIN_NAME## DocumentRoot /var/www/##DOMAIN_NAME##/public_html </VirtualHost> Now I am sure that it is a minor issue if the placeholder is ##DOMAIN_NAME##, !!DOMAIN_NAME!!, {{DOMAIN_NAME}}, or some other variant. However, I now need to standardize with other developers on a project, and we all have a vested interest in having our own placeholder format made standard in the organization. Are there any good reasons for choosing any of these, or others? I am trying to quantify these considerations: Aesthetics and usability. For example, __dict__ may be hard to read as we don't know how many underscores are in there. Compatibility. Will some language try to do something funny with {} syntax in a string (such as PHP does with "Welcome to {$siteName} today!")? Actually, I know that PHP and Python won't, but others? Will a C++ preprocessor choke on ## format? If I need to store the value in some SQL engine, will it not consider something a comment? Any other pitfalls to be wary of? Maintainability. Will the new guy mistake ##SOME_PLACEHOLDER## as a language construct? The unknown. Surely the wise folk here will think of other aspects of this decision that I have not thought of. I might be bikeshedding this, but if there are real issues that might be lurking then I would certainly like to know about them before mandating that our developers adhere to a potentially-problematic convention.

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• Accepting a numerical range in a function call

  - by dekpos

  I have encountered two ways of doing it: void foo(int from, int to); /* 'from' inclusive, 'to' exclusive */ void foo(int startIndex, int rangelength); Has one style historically been preferred over the other? If so, was it just a matter of convention or was it due to some deeper underlying reason? I'm currently programming in Java and noticed that the Arrays class uses the former style. The exclusivity of the to argument felt somewhat unintuitive to me, which led me to ask this question.

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• Estimates, constraint and design [closed]

  - by user65964

  For your next two software projects (assuming that you're getting programming assignments, otherwise consider the program to find the min and max of a set of rational numbers) estimate how much effort they would take before doing them, then keep track of the actual time spent. How accurate were your estimates? State the requirements, constraint, design, estimate (your original estimate and the actual time it took), implementation (conventions used, implement/test path followed.

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• Should Equality be commutative within a Class Hierachy?

  - by vossad01

  It is easy to define the Equals operation in ways that are not commutative. When providing equality against other types, there are obviously situations (in most languages) were equality not being commutative is unavoidable. However, within one's own inheritance hierarchy where the root base class defines an equality member, a programmer has more control. Thus you can create situations where (A = B) ? (B = A), where A and B both derive from base class T Substituting the = with the appropriate variation for a given language. (.Equals(_), ==, etc.) That seems wrong to me, however, I recognize I may be biased by background in Mathematics. I have not been in programming long enough to know what is standard/accepted/preferred practice when programming. Do most programmers just accept .Equals(_)may not be commutative and code defensibly. Do they expect commutativity and get annoyed if it is not. In short, when working in a class hierarchy, should effort me made to ensure Equality is commutative?

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• Array sum of difference of first smallest k elment

  - by prateeak ojha

  Hi i come across this challenge on an online programing challange the task is so simple for ex WE have to variable N and K where N is where N is lenght of array and we have to find sum of duiffrence of K smallest element of array as Sample Input 10 4 1 2 3 4 10 20 30 40 100 200 Sample Output 10 Explanation #0 We have 10 as N size of array and K is 4 here the next N values are array's elments in order to find sum of diffrences we will takek smallest values from array which are 1,2,3,4 then will perform operation(sum of difference) as |1-2| + |1-3| + |1-4| + |2-3| + |2-4| + |3-4| = 10 I tried solving the problem and found a way through which i can solve the problem wit N^3 complexity but my solution is rejected i need a approach to solve the problem with n complexity i still can't figure out a way .. looked at some solution but coud'nt find the exact way to approach. if anybody have a better idea and would like to share it would be appreciable thanks in advance

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• Naming the implementation version of an interface function

  - by bolov

  When I need to write an implementation version of an interface function, I put the implementation function within a impl namespace, but with the same name as the interface function. Is this a bad practice? (the same name part, the namespace part I am confident it’s more than OK). For me, who I write the code, there is no confusion between the two, but I want to make sure this isn’t confusing for someone else. One other option would be to append impl suffix to the function name, but since it is already in a separate namespace named impl it seems redundant. Is there an idiomatic way to do this? E.g.: namespace n { namespace impl { // implementation function (hidden from users) // same name, is it ok? void foo() { // ... //sometimes it needs to call recursively or to call overloads of the interface version: foo(); // calls the implementation version. Is this confusing? n::foo(); // calls the interface version. Is this confusing? // ... } // namespace impl // interface function (exposed to users) void foo() { impl::foo(); } } // namespace n

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• How to start learning Programming? [on hold]

  - by user107080

  Most of the time people ask which programming language to learn which I know is not valid question to ask here and I don't care about 'which' here, I care about 'How'. So, how do I start learning programming from scratch? in other words, what are the steps for absolute beginner to learn programming the right way? I'm sure buying a book and reading it is not the only way in this case. Again, I don't want to ask which but I want also to know if there are specific languages that will make my start as solid as possible because I know that some can hurt my mindset of programming point of view.

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• Single statement if block - braces or no? [on hold]

  - by Zannjaminderson

  Which is better/more generally accepted? This: if(condition) { statement; } Or: if(condition) statement; I tend to prefer the first one, because I think it makes it easier to tell what actually belongs in the if block, it saves others from adding the braces later (or creating a bug by forgetting to), and it makes all your if statements uniform instead of some with braces and some without. The second one, however, is still syntactically correct and definitely more compact. I'm curious to see which is more generally preferred by others though.

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• PHP codinh in real world

  - by user261002

  I know how to write program in PHP and implementation of MVC model. but I really want to practice coding like the coding in real world??? I was wondering is there any specific example or book which can show me the tricks or logic and the way professional programmers consider about coding???

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• Getting the current EnvDTE or IServiceProvider when NOT coding an Addin

  - by Vaccano

  I am coding up some design time code. I want to use this snippet: (Found here) var dte = (EnvDTE.DTE) GetService(typeof(EnvDTE.DTE)); if (dte != null) { var solution = dte.Solution; if (solution != null) { string baseDir = Path.GetDirectoryName(solution.FullName); } } Problem is that this does not compile. (GetService is not a known method call) I tried adding Microsoft.VisualStudio.Shell (and Microsoft.VisualStudio.Shell.10.0) but it did not help. In looking around on the internet I found that you need a IServiceProvider to call this. But all the examples that show how to get an IServiceProvider use a EnvDTE. So, to get the current EnvDTE I need IServiceProvider. But to get an IServiceProvider I need an EnvDTE. (There is a hole in my bucket...) So, here is my question: In a normal WPF Application, how can I get the current instance of EnvDTE? NOTE: I am not looking for any old instance of EnvDTE. I need the one for my current Visual Studio instance (I run 3-4 instances of Visual Studio at a time.)

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• Factories, or Dependency Injection for object instantiation in WCF, when coding against an interface

  - by Saajid Ismail

  Hi I am writing a client/server application, where the client is a Windows Forms app, and the server is a WCF service hosted in a Windows Service. Note that I control both sides of the application. I am trying to implement the practice of coding against an interface: i.e. I have a Shared assembly which is referenced by the client application. This project contains my WCF ServiceContracts and interfaces which will be exposed to clients. I am trying to only expose interfaces to the clients, so that they are only dependant on a contract, not any specific implementation. One of the reasons for doing this is so that I can have my service implementation, and domain change at any time without having to recompile and redeploy the clients. The interfaces/contracts will in this case not change. I only need to recompile and redeploy my WCF service. The design issue I am facing now, is: on the client, how do I create new instances of objects, e.g. ICustomer, if the client doesn't know about the Customer concrete implementation? I need to create a new customer to be saved to the DB. Do I use dependency injection, or a Factory class to instantiate new objects, or should I just allow the client to create new instances of concrete implementations? I am not doing TDD, and I will typically only have one implementation of ICustomer or any other exposed interface.

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• C#,coding with AES

  - by lolalola

  Hi, why i can coding only 128 bytes text? Work: string plainText = "1234567890123456"; Don't work: string plainText = "12345678901234561"; Don't work: string plainText = "123456789012345"; string plainText = "1234567890123456"; byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText); byte[] keyBytes = System.Text.Encoding.UTF8.GetBytes("1234567890123456"); byte[] initVectorBytes = System.Text.Encoding.UTF8.GetBytes("1234567890123456"); RijndaelManaged symmetricKey = new RijndaelManaged(); symmetricKey.Mode = CipherMode.CBC; symmetricKey.Padding = PaddingMode.Zeros; ICryptoTransform encryptor = symmetricKey.CreateDecryptor(keyBytes, initVectorBytes); MemoryStream memoryStream = new MemoryStream(); CryptoStream cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write); cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length); cryptoStream.FlushFinalBlock(); byte[] cipherTextBytes = memoryStream.ToArray(); memoryStream.Close(); cryptoStream.Close(); string cipherText = Convert.ToBase64String(cipherTextBytes); Console.ReadLine();

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• Doing coding in Linux through a virtual machine on Windows VS partitioning

  - by ihaveitnow

  I already have experience with setting up virtual machines, running them and other minor tasks. Im a gamer, so I wont get rid of windows (for now at least...) but I do want to be a great programmer and to be involved with the Open-Source community. Id like to know if its a good idea to do my programming in linux through a virtual machine, vs giving it a partitioned section of the HDD. Id like to know about performance pros and cons and functionality. All responses are appreciated, thanks in advance. The type of programming I intend to dive into : Android Dev, Web Dev, Desktop Dev...More Android and Web right now though. So im looking at C#,C,C++,Java,PHP,HTML,MySQL...Off the top of the dome. I do web designing as well, so dreamweaver is added as an "essential". But im sure I can do dreamweaver files and upload them to the server after programming in Linux...Right? And any info on IDE's in Linux for the above mentioned are appreciated, but i would prefer going the coding route and understanding the essence of whats happening "under the covers" Thanks to all for reading, I appreciate it. Hope this isnt confusing :S

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• Better way of coding this if statment?

  - by HadlowJ

  Hi. I have another question for you very helpful people. I use a lot of if statements many of which are just repeated and im sure could be shortened. This is my current bit of code if (Globals.TotalStands <= 1) { ScoreUpdate.StandNo2.Visible = false; ScoreUpdate.ScoreStand2.Visible = false; ScoreUpdate.ScoreOutOf2.Visible = false; } if (Globals.TotalStands <= 2) { ScoreUpdate.StandNo3.Visible = false; ScoreUpdate.ScoreStand3.Visible = false; ScoreUpdate.ScoreOutOf3.Visible = false; } if (Globals.TotalStands <= 3) { ScoreUpdate.StandNo4.Visible = false; ScoreUpdate.ScoreStand4.Visible = false; ScoreUpdate.ScoreOutOf4.Visible = false; } if (Globals.TotalStands <= 4) { ScoreUpdate.StandNo5.Visible = false; ScoreUpdate.ScoreStand5.Visible = false; ScoreUpdate.ScoreOutOf5.Visible = false; } if (Globals.TotalStands <= 5) { ScoreUpdate.StandNo6.Visible = false; ScoreUpdate.ScoreStand6.Visible = false; ScoreUpdate.ScoreOutOf6.Visible = false; } if (Globals.TotalStands <= 6) { ScoreUpdate.StandNo7.Visible = false; ScoreUpdate.ScoreStand7.Visible = false; ScoreUpdate.ScoreOutOf7.Visible = false; } if (Globals.TotalStands <= 7) { ScoreUpdate.StandNo8.Visible = false; ScoreUpdate.ScoreStand8.Visible = false; ScoreUpdate.ScoreOutOf8.Visible = false; } as you can see there is a huge amount of code to do something simple (which i do on a few other forms as well and im sure there must be a better way of coding this that gets the same result? Im a code noob so please be gentle, code is c# and software is visual studio 2008 pro. Thanks

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• Need advice on C++ coding pattern

  - by Kotti

  Hi! I have a working prototype of a game engine and right now I'm doing some refactoring. What I'm asking for is your opinion on usage of the following C++ coding patterns. I have implemented some trivial algorithms for collision detection and they are implemented the following way: Not shown here - class constructor is made private and using algorithms looks like Algorithm::HandleInnerCollision(...) struct Algorithm { // Private routines static bool is_inside(Point& p, Object& object) { // (...) } public: /** * Handle collision where the moving object should be always * located inside the static object * * @param MovingObject & mobject * @param const StaticObject & sobject * @return void * @see */ static void HandleInnerCollision(MovingObject& mobject, const StaticObject& sobject) { // (...) } So, my question is - somebody advised me to do it "the C++" way - so that all functions are wrapped in a namespace, but not in a class. Is there some good way to preserve privating if I will wrap them into a namespace as adviced? What I want to have is a simple interface and ability to call functions as Algorithm::HandleInnerCollision(...) while not polluting the namespace with other functions such as is_inside(...) Of, if you can advise any alternative design pattern for such kind of logics, I would really appreciate that...

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