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  • How do languages handle side effects of compound operators?

    - by Kos
    Hello, Assume such situation: int a = (--t)*(t-2); int b = (t/=a)+t; In C and C++ this is undefined behaviour, as described here: Undefined Behavior and Sequence Points However, how does this situation look in: JavaScript, Java, PHP... C# well, any other language which has compound operators? I'm bugfixing a Javascript - C++ port right now in which this got unnoticed in many places. I'd like to know how other languages generally handle this... Leaving the order undefined is somehow specific to C and C++, isn't it?

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  • Question on Addressing Modes in PDP-11 Assembler

    - by lego69
    I have small question about pdp-11(simulator), I have this command (it begins from the address 1000) add 2500, #2500 and this initial list: register/address - initial value pc 1000 sp 600 2500 3000 and I want to know how this small snippet exactly runs, in my booklet I found that: firstly it reads inforamtion from the address 1000, inside this address we have value 066727, after we read number from the address 1002, AND VALUE MUST BE 2500(because of add 2500, #2500), but in my booklet I have 1474 without any explanations why, I know that I have here relative addressing mode, but why 1474 inside the address 1002 and not 2500, thanks in advance for any help

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  • Find three numbers appeared only once

    - by shilk
    In a sequence of length n, where n=2k+3, that is there are k unique numbers appeared twice and three numbers appeared only once. The question is: how to find the three unique numbers that appeared only once? for example, in sequence 1 1 2 6 3 6 5 7 7 the three unique numbers are 2 3 5. Note: 3<=n<1e6 and the number will range from 1 to 2e9 Memory limits: 1000KB , this implies that we can't store the whole sequence. Method I have tried(Memory limit exceed): I initialize a tree, and when read in one number I try to remove it from the tree, if the remove returns false(not found), I add it to the tree. Finally, the tree has the three numbers. It works, but is Memory limit exceed. I know how to find one or two such number(s) using bit manipulation. So I wonder if we can find three using the same method(or some method similar)? Method to find one/two number(s) appeared only once: If there is one number appeared only once, we can apply XOR to the sequence to find it. If there are two, we can first apply XOR to the sequence, then separate the sequence into 2 parts by one bit of the result that is 1, and again apply XOR to the 2 parts, and we will find the answer.

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  • Hex Decompilers for PIC

    - by Chathuranga Chandrasekara
    I've faced to a problem with a PIC Micro controller. I have a micro-controller programmed by me long time ago and I lost the relevant source code and the schematic diagrams. Now I need to invert the value of a port. I can do this using some NOT gates but it is a big hassle to do so. or alternatively I will need to write the whole program back. I don't expect to see the code back in PIC C or MikroC. Having an understandable assembly code would be sufficient. So do anyone has any experience on a good HEX decompiler that I can use for this purpose? Any comments based on your experience? :)

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  • Testing Async downloads with ASIHTTPRequest

    - by Baishampayan Ghose
    I am writing a simple library using ASIHTTPRequest where I am fetching URLs in an async manner. My problem is that the main function that I have written to test my lib exits before the async calls are finished. I am very new to Obj C and iPhone development, can anyone suggest a good way to wait before all the requests are finished in the main function? Currently, my main function looks like this - int main(int argc, char *argv[]) { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; IBGApp *ibgapp = [[IBGApp alloc] init]; IBGLib *ibgl = [[IBGLib alloc] initWithUsername:@"joe" andPassword:@"xxx"]; // The two method calls below download URLs async. [ibgl downloadURL:@"http://yahoo.com/" withRequestDelegate:ibgapp andRequestSelector:@selector(logData:)]; [ibgl downloadURL:@"http://google.com/" withRequestDelegate:ibgapp andRequestSelector:@selector(logData:)]; [pool release]; return 0; // I reach here before the async calls are done. } So what is the best way to wait till the async calls are done? I tried putting sleep, but obviously doesn't work.

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  • From interpeted to native code: "dynamic" languages compiler support

    - by Daniel
    First, I am aware that dynamic languages is a term used mainly by a vendor; I am using it just to have a container word to include languages like Perl (a favorite of mine), Python, Tcl, Ruby, PHP and so on. They are interpreted but I am interested here to refer to languages featuring strong capability to support the programmer efficiency and the support for typical constructs of modern interpreted languages My question is: there are dynamic languages can be compiled efficiently in native executable code - typically for Windows platforms? Which ones? Maybe using some third part ad-hoc tools? I am not talking about huge executables carrying with them a full interpreter or some similar tricks nor some smart module able to include its own dependances or some required modules, but a honest, straight, standard, solid executable code. If not, there is some technical reason inhibiting the availability of such a best-of-both-world feature? Thanks! Daniel

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  • activate RTTI in c++

    - by benjamin button
    Hi, Can anybody tell me how to activate RTTI in c++ when working on unix. I heard that it can be disabled and enabled. on my unix environment,how could i check whether RTTI is enabled or disabled?

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  • What is the best algorithm for this array-comparison problem?

    - by mark
    What is the most efficient for speed algorithm to solve the following problem? Given 6 arrays, D1,D2,D3,D4,D5 and D6 each containing 6 numbers like: D1[0] = number D2[0] = number ...... D6[0] = number D1[1] = another number D2[1] = another number .... ..... .... ...... .... D1[5] = yet another number .... ...... .... Given a second array ST1, containing 1 number: ST1[0] = 6 Given a third array ans, containing 6 numbers: ans[0] = 3, ans[1] = 4, ans[2] = 5, ......ans[5] = 8 Using as index for the arrays D1,D2,D3,D4,D5 and D6, the number that goes from 0, to the number stored in ST1[0] minus one, in this example 6, so from 0 to 6-1, compare each res array against each D array My algorithm so far is: I tried to keep everything unlooped as much as possible. EML := ST1[0] //number contained in ST1[0] EML1 := 0 //start index for the arrays D While EML1 < EML if D1[ELM1] = ans[0] goto two if D2[ELM1] = ans[0] goto two if D3[ELM1] = ans[0] goto two if D4[ELM1] = ans[0] goto two if D5[ELM1] = ans[0] goto two if D6[ELM1] = ans[0] goto two ELM1 = ELM1 + 1 return 0 //If the ans[0] number is not found in either D1[0-6], D2[0-6].... D6[0-6] return 0 which will then exclude ans[0-6] numbers two: EML1 := 0 start index for arrays Ds While EML1 < EML if D1[ELM1] = ans[1] goto three if D2[ELM1] = ans[1] goto three if D3[ELM1] = ans[1] goto three if D4[ELM1] = ans[1] goto three if D5[ELM1] = ans[1] goto three if D6[ELM1] = ans[1] goto three ELM1 = ELM1 + 1 return 0 //If the ans[1] number is not found in either D1[0-6], D2[0-6].... D6[0-6] return 0 which will then exclude ans[0-6] numbers three: EML1 := 0 start index for arrays Ds While EML1 < EML if D1[ELM1] = ans[2] goto four if D2[ELM1] = ans[2] goto four if D3[ELM1] = ans[2] goto four if D4[ELM1] = ans[2] goto four if D5[ELM1] = ans[2] goto four if D6[ELM1] = ans[2] goto four ELM1 = ELM1 + 1 return 0 //If the ans[2] number is not found in either D1[0-6], D2[0-6].... D6[0-6] return 0 which will then exclude ans[0-6] numbers four: EML1 := 0 start index for arrays Ds While EML1 < EML if D1[ELM1] = ans[3] goto five if D2[ELM1] = ans[3] goto five if D3[ELM1] = ans[3] goto five if D4[ELM1] = ans[3] goto five if D5[ELM1] = ans[3] goto five if D6[ELM1] = ans[3] goto five ELM1 = ELM1 + 1 return 0 //If the ans[3] number is not found in either D1[0-6], D2[0-6].... D6[0-6] return 0 which will then exclude ans[0-6] numbers five: EML1 := 0 start index for arrays Ds While EML1 < EML if D1[ELM1] = ans[4] goto six if D2[ELM1] = ans[4] goto six if D3[ELM1] = ans[4] goto six if D4[ELM1] = ans[4] goto six if D5[ELM1] = ans[4] goto six if D6[ELM1] = ans[4] goto six ELM1 = ELM1 + 1 return 0 //If the ans[4] number is not found in either D1[0-6], D2[0-6].... D6[0-6] return 0 which will then exclude ans[0-6] numbers six: EML1 := 0 start index for arrays Ds While EML1 < EML if D1[ELM1] = ans[5] return 1 ////If the ans[1] number is not found in either D1[0-6]..... if D2[ELM1] = ans[5] return 1 which will then include ans[0-6] numbers return 1 if D3[ELM1] = ans[5] return 1 if D4[ELM1] = ans[5] return 1 if D5[ELM1] = ans[5] return 1 if D6[ELM1] = ans[5] return 1 ELM1 = ELM1 + 1 return 0 As language of choice, it would be pure c

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  • When is a scala partial function not a partial function?

    - by Fred Haslam
    While creating a map of String to partial functions I ran into unexpected behavior. When I create a partial function as a map element it works fine. When I allocate to a val it invokes instead. Trying to invoke the check generates an error. Is this expected? Am I doing something dumb? Comment out the check() to see the invocation. I am using scala 2.7.7 def PartialFunctionProblem() = { def dream()() = { println("~Dream~"); new Exception().printStackTrace() } val map = scala.collection.mutable.HashMap[String,()=>Unit]() map("dream") = dream() // partial function map("dream")() // invokes as expected val check = dream() // unexpected invocation check() // error: check of type Unit does not take parameters }

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  • The next step & technology towards web services.

    - by webzide
    Hi, My name is Dennis and I am pretty ambitious of creating the next big thing for the web. I have ideas but now I gotta get to work to learn the tools. I am learning Javascript. I don't know if next step for me to take is PHP or some suggests RUBY on Rails. What are the pros and cons. With your experience, I wish you could hint me to the right direction. Thanks. I don't mind working hard. My goal is to create a comprehensive and secure web service platform as well as a fast and user friendly UI.

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  • How can we receive a volume attaching notification

    - by Benjamin
    When a volume is attached to file system, on Windows, the Window explorer detects the volume and refreshes automatically. I wonder the technique. How do an program(include device driver) get the notification? -Of course, it doesn’t mean a polling. I want to get an event(or a message). I would like to get the notification when a network volume(like SMB) is attached. Thanks in advance.

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  • How to flush DNS cache in Windows Mobile programmatically?

    - by Bounded
    Hello, My windows mobile application (written in C# with the compact framework) needs to know if a particular machine is active or not. To achieve this goal, I thought to use a ping mechanism. I tried to use the Ping class implemented in the opennetcf framework (the System.Net.NetworkInformation.Ping class for the .NET Framework is not part of the compact framework). Because I give to the Ping.Send function a host name, it first tries to resolve this host name and to retrieve an IP address. But i observe the following problem : If the first dns resolution fails (because the network is down at this moment), and if the application tries immediately again to send the ping, it fails too, even if the network is note down anymore. I check with a famous network protocol analyzer and i saw that only the requests concerning the first dns resolution are sent. The requests concerning the dns resolution of the second ping are not sent. Why is the second dns request not sent ? Is there any dns cache mechanism on such Windows Mobile devices ? If yes, can this mechanism beeing flushed programmatically ? EDIT : I gave up finding a solution to this DNS flush. I chose to ping an IP adress instead of a name machine. The problem of pinging an hard coded adress IP is that we have to be 100% sure that this IP will not change. The gateway IP can be used because it's always reachable (if it does not, it means the network is down).

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  • How to gain greater control of network packets on Android

    - by mauvehead
    I'm looking to design an application that will require some deep control over IP packets. Looking over the reference guide on the developers site at Android I see very limited control over packets from java.net:SocketOptions and java.net:DatagramPacket. Specifically I'm looking to control the individual bits within the packet to set TCP Flags, SYN/ACK/RST, and so forth. Based on the docs I am assuming I cannot do this within the Java API provided by Android and I'm guessing I'll have to do it some other way? Anyone have any insight on this?

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  • hide cursor on remote terminal

    - by Tyler
    I have an open socket to a remote terminal. Using this SO answer I was able to put that terminal into character mode. My question is, how do I hide the cursor in the remote terminal using this method? Thanks!

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  • How to iterate over modifed std::map values?

    - by Frank
    I have an std::map, and I would like to define an iterator that returns modified values. Typically, a std::map<int,double>::iterator iterates over std::pair<int,double>, and I would like the same behavior, just the double value is multiplied by a constant. I tried it with boost::transform_iterator, but it doesn't compile: #include <map> #include <boost/iterator/transform_iterator.hpp> #include <boost/functional.hpp> typedef std::map<int,double> Map; Map m; m[100] = 2.24; typedef boost::binder2nd< std::multiplies<double> > Function; typedef boost::transform_iterator<Function, Map::value_type*> MultiplyIter; MultiplyIter begin = boost::make_transform_iterator(m.begin(), Function(std::multiplies<double>(), 4)); // now want to similarly create an end iterator // and then iterate over the modified map The error is: error: conversion from 'boost ::transform_iterator< boost::binder2nd<multiplies<double> >, gen_map<int, double>::iterator , boost::use_default, boost::use_default >' to non-scalar type 'boost::transform_iterator< boost::binder2nd<multiplies<double> >, pair<const int, double> * , boost::use_default, boost::use_default >' requested What is gen_map and do I really need it? I adapted the transform_iterator tutorial code from here to write this code ...

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  • Create UML diagrams after or before coding?

    - by ajsie
    I can clearly see the benefits of having UML diagrams showing your infrastructure of the application (class names, their members, how they communicate with each other etc). I'm starting a new project right now and have already structured the database (with visual paradigm). I want to use some design patterns to guide me how to code the classes. I wonder, should I code the classes first before I create UML diagram of it (maybe out of the code... seems possible) or should I first create UML diagram and then code (or generate code from the UML, seems possible that too). What are you experiences telling you is the best way?

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  • Monitoring outgoing internet traffic

    - by Frane
    Is there a way to monitoring internet traffic programatically? I would like to log the pages users are visiting on the Internet. Can this be achieved with .NET code, is there a 3rd party .NET component that could be used to retrieved data. Information about Internet traffic must be stored to a database so I cannot use a plugin or something for IE. We are also looking to include this code into our existing product so we cannot use a 3rd party product that cannot be redistributed. It would be cool if this thing could monitor traffic for all browsers but monitoring IE traffic might also be sufficient.

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  • php functions new php developers should be aware of

    - by John
    Can people suggest a list of common or popular php functions that new/junior programmers should be aware of so that they don't "re-invent-the-wheel" so to speak? For example, I've seen a lot of new coders try to write their own date parsing functions when a combination of date(), strtotime() and time() can do everything their looking for. Any other ones you guys want to add to this list? Thanks

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  • F#: how to find Cartesian power

    - by Nike
    I have a problem with writing a Cartesian power function. I found many examples about calculating Cartesian Product, but no one about Cartesian power. For example, [1;2] raised to power 3 = [ [1;1;1] ; [1;1;2] ; [1;2;1] ; [1;2;2] ; [2;1;1] ; [2;1;2] ; [2;2;1]; [2;2;2] ] I use following code to calculate Cartesian Product: let Cprod U V = let mutable res = [] for u in U do for v in V do res <- res @ [[u;v]] res And trying to calculate Cartesian power. I use following code to calculate Cartesian Product: let Cpower U n = let mutable V = U for i=0 to n-1 do V <- Dprod U V V Visual Studio said: Error The resulting type would be infinite when unifying ''a' and ''a list'. I will thankful for any help and links.

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  • what's an option strict and explicit?

    - by Ygam
    I saw this post: "Typos… Just use option strict and explicit please.. during one software development project, which I was on as a consultant, they were getting ridiculous amounts of errors everywhere… turned out the developer couldn’t spell and would declare variables with incorrect spelling.. no big deal, until you use the correct spelling when you’re assigning a value to it… and you had option explicit off. Ouch to them…" what is an option strict and explicit anyway? I have googled it up but can't get the idea (because mostly it's Visual Basic, I'm doing PHP)

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  • display records which exist in file2 but not in file1

    - by Phoenix
    log file1 contains records of customers(name,id,date) who visited yesterday log file2 contains records of customers(name,id,date) who visited today How would you display customers who visited yesterday but not today? Constraint is: Don't use auxiliary data structure because file contains millions of records. [So, no hashes] Is there a way to do this using Unix commands ??

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  • What are the worst examples of moral failure in the history of software engineering?

    - by Amanda S
    Many computer science curricula include a class or at least a lecture on disasters caused by software bugs, such as the Therac-25 incidents or Ariane 5 Flight 501. Indeed, Wikipedia has a list of software bugs with serious consequences, and a question on StackOverflow addresses some of them too. We study the failures of the past so that we don't repeat them, and I believe that rather than ignoring them or excusing them, it's important to look at these failures squarely and remind ourselves exactly how the mistakes made by people in our profession cost real money and real lives. By studying failures caused by uncaught bugs and bad process, we learn certain lessons about rigorous testing and accountability, and we make sure that our innocent mistakes are caught before they cause major problems. There are kinds of less innocent failure in software engineering, however, and I think it's just as important to study the serious consequences caused by programmers motivated by malice, greed, or just plain amorality. Thus we can learn about the ethical questions that arise in our profession, and how to respond when we are faced with them ourselves. Unfortunately, it's much harder to find lists of these failures--the only one I can come up with is that apocryphal "DOS ain't done 'til Lotus won't run" story. What are the worst examples of moral failure in the history of software engineering?

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