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  • MySQL - Join as zero if record Not IN

    - by Zurahn
    To explain by example, take two tables, A and B Table A id foo 1 x 2 y 3 z Table B id aid bar 1 3 50 2 1 100 An example join SELECT foo, bar FROM a, b WHERE a.id = b.aid; Garners a result of foo bar z 50 x 100 What I would like to do is get all values of foo and for any instances where there isn't a corresponding bar value, return 0 for that column. My best guess was something along the lines of SELECT foo, bar AS br FROM a, b WHERE a.id = b.aid OR a.id NOT IN (SELECT aid FROM b); But that returns duplicates and non-zero values for bar. Possible?

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  • Choosing the right and learning assembler for compiler-writing

    - by X A
    I'm writing a compiler and I have gone through all the steps (tokenizing, parsing, syntax tree structures, etc.) that they show you in all the compiler books. (Please don't comment with the link to the "Resources for writing a compiler" question!). I have chosen to use NASM together with alink as my backend. Now my problem is: I just can't find any good resources for learning NASM and assembly in general. The wikibook (german) on x86 assembly is horrible. They don't even explain the code they write there, I currently can't even get simple things like adding 1 to 2 and outputting the result working. Where can I learn NASM x86 assembly?

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  • How do I use a UIView subclass as a container?

    - by dxq
    I'm trying to subclass UIView to create a custom view that is essentially a container. The subclass contains a UILabel and a UIImageView- I can't make either of them show up. Here's an example of what I've been trying: In my main view controller: - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) { ViewClass *myView = [[ViewClass alloc] initWithFrame:CGRectMake(100, 100, 150, 150)]; [view addSubview:myView]; } return self; } In my UIView subclass: - (id)initWithFrame:(CGRect)frame { if (self = [super initWithFrame:frame]) { UILabel *word = [[[UILabel alloc] initWithFrame:[self bounds]] autorelease]; word.text = @"WHY ISN'T THIS SHOWING UP!?"; [self addSubview:word]; } return self; } Can anyone explain what I'm doing wrong? I'm way out of practice with UIKit and Obj-C, and I figure I'm probably missing something obvious.

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  • What is this Design Pattern?

    - by Can't Tell
    I read the Wikipedia articles on FactoryMethod and AbstractFactory but the following code doesn't seem to fit anywhere. Can someone explain to me what the following pattern is or if it is an anti-pattern? interace PaymentGateway{ void makePayment(); } class PaypalPaymentGateway implements PaymentGateway { public void makePayment() { //some implementation } } class AuthorizeNetPaymentGateway implements PaymentGateway { public void makePayment() { //some implementation } } class PaymentGatewayFacotry{ PaymentGateway createPaymentGateway(int gatewayId) { if(gatewayId == 1) return PaypalPaymentGateway(); else if(gatewayId == 2) return AuthorizeNetPaymentGateway(); } } Let's say the user selects the payment method using a radio button on an html page and the gatewayId is derived from the radio button value. I have seen code like this and thought it was the AbstractFactory pattern but after reading the Wikipedia article, I'm having doubts.

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  • Allowing AsyncTask to Manipulate Values in Different Activity Classes

    - by Matt
    Hi guys, This title may seem strange, so let me try to explain what I'm trying to do. I have several activity classes, each representing a different view in my application. My initial activity class gets loaded when the application launches. The user enters values and eventually a TCP socket is opened, and I then use AsyncTask to listen for and respond to messages from the server. I'd like for this AsyncTask class to essentially listen until the app is closed/error condition reached, and be able to update values in other activity classes after they are started. Does this make sense (it's been a long, frustrating night)? I know that static activity class references are bad practice, and touching the UI thread from other activities is bad as well, but I'm having trouble finding a clean solution to this problem. Maybe using AsyncTask is not the best approach here? Should I be using a service instead or something else entirely? Thanks in advance.

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  • Programming tutorials for people with zero experience

    - by www.aegisub.net
    A friend of mine is interested in learning how to program computers, but she knows nothing about programming. I suggested that Python might be a good language to start with, but after some googling, I couldn't find any tutorials that covered both programming and Python in an adequate way. I don't want her to go through the tiresome "learn algorithms in pseudocode first" routine. Instead, I'd like a tutorial that will explain the basic ideas while working towards a real goal, e.g. a very simple console game. Does anyone know of any such tutorials? Do you think that I'm mistaken in how I'm handling this? Is Python a bad choice? I know that something like C, C++ or Java won't work - too many details will be very counterproductive. On the other hand, I think that Lisp might be too mathematical and abstract. Python, on the other hand, will let her even do something like coding primitive graphical games in a short period of time.

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  • WebClient.DownloadString() Not Producing Exact HTML

    - by Ryan Fuentes
    So here's the deal. I'm creating a spider bot for a website that scans all the product pages and records the product data. I'm using C# and the WebClient library to download the HTML string. The site I'm crawling must be specially made because the HTML that is received from WebClient.DownloadString() is different than the HTML that I get when I view the source of the HTML when visiting it on a browser. This seems intentional because the only info I can't get is the price. Does anyone know a workaround for this problem or can anyone explain what is happening? Thanks.

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  • NetNamedPipe: varying response time when communication is idling

    - by Sven Künzler
    I have two WCF apps communicating one-way over named pipes. All is nice, except for one thing: Normally, the request/response cycle takes zero (marginal) time. However, if there was a time span of, say, half a minute without any communication, the request/response increases up to ~300-500ms. I looked around the net and I got the idea of using a heart beat/ping mechanism to keep the communication channel busy. Using trial and error I found that when doing a request each 10 seconds, the response times stay low. Starting at around 15s intervals, the "hiccup" response times begin to appear. Now I'm wondering where this phenomenon is originating from. I tried setting alle conceivable timeouts on both sides to 1 minute, but that did not help. Can anybody explain what's going on there?

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  • How to Detect Trusted Connection in Crystal Reports using VB.NET?

    - by Michael
    I have some Crystal Reports connecting to a Sql Server db that I would like to detect whether the connection is trusted or whether I need to supply the log on info (reports are not supplied by me so I can't control the connect method). If I just blindly supply login credentials, it won't connect if it is a trusted connection. The following does not work: oRpt = oCR.OpenReport("C:\MyReport.rpt") if oRpt.Database.Tables(1).ConnectionProperties.Item("Integrated Security") = True then 'trusted connection else 'supply login credentials end if It gives the following error: Operator '=' is not defined for type 'IConnectionProperty' and type 'Boolean'. I cannot find how create a construct in vb.net for IConnectionProperty. I can't find any documents from Crystal that explain it. I am using Crystal Reports XI - Developer

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  • segmentation fault

    - by gcc
    int num_arrays; char *p[20]; char tempc; int i=0; do { p[i]=malloc(sizeof(int)); scanf("%s",p[i]); tempc=p[i]; ++i; }while(tempc=='x'); num_arrays=atoi(p[0]); When i write num_arrays=atoi(..),gcc give me segmentation fault or memory stack is exceeded, I don't understand why it behaves like that can anyone explain, why?

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  • Result of Long Positive Integers & Search and element in array..

    - by AGeek
    Hi, I have two Questions for which I cannot find answers by googling, but I find these questions very important for preparation.. Kindly explain only the logic, I will be able to code. In Search of Efficient Logic..... in terms of Memory and Time. WAP to add two long positive integers. What Data structure / data type we can use to store the numbers and result. What is the best way to search an element from an array in shortest time. Size of the array could be large enough, and any elements could be stored in the array(i.e. no range). Thanks.

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  • Care to be taken when serving static content (JS, CSS, Media) from different domain?

    - by Aahan Krish
    Let me try to explain by example. Say website is hosted at example.com (NOT www.example.com). In order to serve static content cookie-free, I've chosen to use a different domain example-static.com. Now, lets consider that my static content is currently served like this: http://example.com/js/script.js http://example.com/css/style.css http://example.com/media/image.jpg ** Now I create a CNAME record aliasing example-static.com to my main domain i.e. example.com so that the static content is served as such: http://example-static.com/js/script.js http://example-static.com/css/style.css http://example-static.com/media/image.jpg ** Is that all I have to do? Will all browsers execute JavaScript files and load web fonts without any security concerns? OR should I be using some .htaccess rules to modify header information and the like? PS: It would be great if you can provide what rules should be added, if need be.

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  • Regex Question..

    - by Josh
    Hello everyone- In my C# Console App I'm trying to use Regex to search a string to determine if there is a match or not. Below is my code but it is not quite working right so I will explain further. sSearchString is set to "_One-Call_Pipeline_Locations" and pDS.Name is a filename it is searching against. Using the code below it is set to true for Nevada_One-Call_Pipeline_Locations and Nevada_One-Call_Pipeline_LocationsMAXIMUM. There should be a match for Nevada_One-Call_Pipeline_Locations But Not for Nevada_One-Call_Pipeline_LocationsMAXIMUM. How can I change my code to do this properly? Thanks in advance if (Regex.IsMatch(pDS.Name, sSearchString))

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  • java protected method accessibility

    - by JavaUser
    In the below code the Consumer class can access the protected method of Parent class.How is it possible since there is no relation between Parent and Consumer class.Please explain class Parent { public void method1(){ System.out.println("PUBLIC METHOD"); } private void method2(){ System.out.println("PRIVATE METHOD"); } protected void method3(){ System.out.println("PROTECTED METHOD"); } } public class Consumer { public static void main(String[] args){ Parent parentObj = new Parent(); parentObj.method1(); //parentObj.method2(); parentObj.method3(); } } Thanks

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  • Custom components vs default components in GUI Design. Which is more practical? (.NET)

    - by AlexRednic
    Ok, so is it better to create my own components (Either inherit them from existing ones or creating them from scratch) or to use the ones that come by default? I'm asking this under the umbrella of scalability, overhead and other factors that my contribute on each of the choices. UPDATE: Sorry if I'm to vague. I don't really know how to explain myself better. Isn't it a good idea to inherit each default component? For example what if I'm to design a rather large application and for example i need to change the display format on a DateTimePicker. Wouldn't it better to think ahead and inherit it and use the inherited component instead of the defaults? But, wouldn't it add a lot of overhead in small applications?

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  • iPhone - a question about @property

    - by Roger
    Hi, I am kind of newbie on Objective-C and I was looking at a code, trying to understand a few things, and I come across with this .h file: there was a declaration like that on the @interface section MyVideoClass *contrast_; then below we have @property (nonatomic, retain) MyVideoClass *contrast; @property (nonatomic, retain) FetchClass *fetchMe; The strange part is that the first has an underscrore after the name and the second one, doesn't. The other strange thing is that the guy has a call to these properties like this: FetchClass *fetchOne = [self.fetchMe contrast]; What kind of call is that? This seems pretty insane to me. I simply cannot understand what is going on here, but the code works. pretty insane. Can you guys explain me that? Forgive the stupid question, but I am still learning... thanks

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  • Changing Color with LinearLayout and TextView in Java (Android)

    - by Rob S.
    I'm a relatively new Android developer and I noticed what seems like an oddity to me that I'm hoping someone can explain. I have LinearLayout ll. This line of code fails for me when executed: ll.setBackgroundColor(R.color.white); However this line of code works: ll.setBackgroundResource(R.color.white); I assume its simply because I have white defined in my resources. However, I've also tried passing 0xFFFFFF in setBackgroundColor() and that doesn't work either. Similarly with my TextView text this line of code fails when executed: text.setTextColor(R.color.white); I can see my TextView so I know I initialized it correctly (like my LinearLayout which I can also see). So I guess my question boils down to: How do I properly use LinearLayout.setBackgroundColor() and TextView.setTextColor() ? Thanks a ton in advance. I've read through the docs and tried to find information online via googling and haven't come up with anything.

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  • How does Play recognize a particular websocket message?

    - by noncom
    I am looking at the websocket-chat example. It unveils much, but I still cannot get something. I understand how messages are received, processed and sent on the web page side. However, Play captures websocket messages by means of the receive method of an Akka actor. In the websocket-chat, there are several cases in this method, but I don't get, how does it know which websocket message should be mapped to which case. In fact, I don't understand the path that a websocket message follows upon entering Play's domain, how is it processed and how can different message types/kinds be sent from the webpage. I have not find any info or sources related to this. Could please someone explain this or point to some kind of a good reference? UPDATE: The link to the original example.

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  • Purpose of Instance Methods vs. Class Methods in Objective-C

    - by qegal
    I have checked out all these questions... Difference Class and Instance Methods Difference between class methods and instance methods? Objective-C: Class vs Instance Methods? ...and all they explain is how instance methods are used on instances of a class and class methods are used with the class name, when a message is sent to a class object. This is helpful, but I'm curious to know why one would use a class method vs. an instance method. I'm fairly new to iOS application development, and usually use class methods, and I feel like I'm doing something wrong. Thanks in advanced!

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  • C++ streams question (explanation of comment in code)

    - by skyeagle
    I am playing around with the fastCGI application found here. The following comment is in the code: if (content) delete []content; // If the output streambufs had non-zero bufsizes and // were constructed outside of the accept loop (i.e. // their destructor won't be called here), they would // have to be flushed here. My knowledge of C++ streams is rather weak. Could someone please explain the following: which streambufs are being referred to in the comment? under what conditions would the streambufs had non-zero bufsizes? last but not the least, can someone point to a resource (pun intended) online that provides a clear but gentle introduction to C++ IO streams?

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  • Do you have to create a View Controller to move between views?

    - by Frames84
    I want a single startup view with a button and a welcome screen. When the button is pressed I then want to navigate to a second view which contains a table view and toolbar. I've tried creating a ViewController but my button is shown on all views. I just want a single view, then when it's pressed i go to the next view and the 'real' app starts. Can someone please try and explain the best architecture to do this? (like in chapter 6 of beginning iPhone 3 Development by Dave Mark and Jeff LaMarche ) Thanks

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  • Problem accessing base member in derived constructor

    - by LeopardSkinPillBoxHat
    Given the following classes: class Foo { struct BarBC { protected: BarBC(uint32_t aKey) : mKey(aKey) mOtherKey(0) public: const uint32_t mKey; const uint32_t mOtherKey; }; struct Bar : public BarBC { Bar(uint32_t aKey, uint32_t aOtherKey) : BarBC(aKey), mOtherKey(aOtherKey) // Compile error here }; }; I am getting a compilation error at the point indicated: error: class `Foo::Bar' does not have any field named `mOtherKey'. Can anyone explain this? I suspect it's a syntactical problem due to my Bar class being defined within the Foo class, but can't seem to find a way around it. This is simple public inheritance, so mOtherKey should be accessible from the Bar constructor. Right? Or is it something to do with the fact that mOtherKey is const and I have already initialised it to 0 in the BarBC constructor?

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  • dynamic memory allocation of 2d array in which columns are of different size

    - by vishal kumar
    i want to create a 2d array dynamically in c++ language. But in that 2d array columns should be of different size. i mean to say that 2d array should not be in M * N. It should be something like.... 1 2 next line 3 4 5 next line 2 3 4 5 next line 5 next line 4 5 7 I am able to create 2d array in above manner but how to display content of array continously create a problem for me. Please anyone explain me how to come up with this problem.

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  • What's the difference between the box-model bug and the new box-sizing CSS?

    - by RKS
    In days (long past for some, and still present for others) the box-model bug was a bane to their existence. The idea that an element's width included the margin, border, and padding was blasphemous and an abomination to their senses. So we got away from it after thousands of internet blogs about the box-model hack. Now we get box-sizing, which will, wait for it, allow you to specify that a width contains the border, the margin, and the padding. We plaster a trendy new name for it, "CSS3 Flexbox," and now it's the freedom designers have been looking for. For those logical people who saw the box-model bug as not the bug and the W3C as the actual bug, this comes as a surprise. A reintroduction of this so-called bug and now we call it an enhancement? So can someone explain why this is different? I am honestly confused about this.

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  • About the String#substring() method

    - by alain.janinm
    If we take a look at the String#substring method implementation : new String(offset + beginIndex, endIndex - beginIndex, value); We see that a new String is created with the same original content (parameter char [] value). So the workaround is to use new String(toto.substring(...)) to drop the reference to the original char[] value and make it eligible for GC (if no more references exist). I would like to know if there is a special reason that explain this implementation. Why the method doesn't create herself the new shorter String and why she keeps the full original value instead? The other related question is : should we always use new String(...) when dealing with substring?

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