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  • Should I make sure arguments aren't null before using them in a function.

    - by Nathan W
    The title may not really explain what I'm really trying to get at, couldn't really think of a way to describe what I mean. I was wondering if it is good practice to check the arguments that a function accepts for nulls or empty before using them. I have this function which just wraps some hash creation like so. Public Shared Function GenerateHash(ByVal FilePath As IO.FileInfo) As String If (FilePath Is Nothing) Then Throw New ArgumentNullException("FilePath") End If Dim _sha As New Security.Cryptography.MD5CryptoServiceProvider Dim _Hash = Convert.ToBase64String(_sha.ComputeHash(New IO.FileStream(FilePath.FullName, IO.FileMode.Open, IO.FileAccess.Read))) Return _Hash End Function As you can see I just takes a IO.Fileinfo as an argument, at the start of the function I am checking to make sure that it is not nothing. I'm wondering is this good practice or should I just let it get to the actual hasher and then throw the exception because it is null.? Thanks.

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  • How to find scrollable elements in DOM using XPath?

    - by ak.
    Basically I need to find all elements on the page that have a scrollbar (vertical or horizontal) How to tell if an element has a scrollbar and can actually be scrolled? I found this code snippet on jsperf. Is it possible to capture the logic behind the code into and XPath expression? Or are there any other ways to check for scrollbars? Added: Just to explain what I'm trying to do: I'm developing extension for Firefox. Basically it introduces Vim-style mouseless shortcuts (I know there is Vimperator and Pentadactyl...). One of the features I'd like to implement is to allow the use to select the container that's scrolled with j/k keys. That's why I need to discover all scrollable elements on any given random page.

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  • Add all lines multiplied by another line in another table

    - by russell
    Hi, I hope I can explain this good enough. I have 3 tables. wo_parts, workorders and part2vendor. I am trying to get the cost price of all parts sold in a month. I have this script. $scoreCostQuery = "SELECT SUM(part2vendor.cost*wo_parts.qty) as total_score FROM part2vendor INNER JOIN wo_parts ON (wo_parts.pn=part2vendor.pn) WHERE workorder=$workorder"; What I am trying to do is each part is in wo_parts (under partnumber [pn]). The cost of that item is in part2vendor (under part number[pn]). I need each part price in part2vendor to be multiplied by the quantity sold in wo_parts. The way all 3 tie up is workorders.ident=wo_parts.workorder and part2vendor.pn=wo_parts.pn. I hope someone can assist. The above script does not give me the same total as when added by calculator.

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  • deny direct access to a php file by typing the link in the url

    - by aeonsleo
    hi, I am using php session for a basic login without encryption for my site. I want to prevent a user from directly accessing a php page by typing the url when he/she is not signed in. But this is not happening. I am using session_start(), initializing session variables and aslo unsetting and destroying sesssion during logout. Also if I type the link in a different browser the page is getting displayed. I am not very well versed with php , only a beginner. I googled for such problem and found few alternatives as keeping all files in a seperate folder from the web root, using .htaccess etc. Can someone explain in simple terms what could be a good solution.thanks in advance.

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  • pointer being freed was not allocated

    - by kudorgyozo
    Hello i have the following error: malloc: * error for object 0x2087000: pointer being freed was not allocated * set a breakpoint in malloc_error_break to debug I have no idea what object that is. I don't know how to find it. Can anybody explain to me how (and where) to use malloc_history. I have set a breakpoint in malloc_error_break but i couldn't find out what object is at that address. I receive this after removing an object from an nsmutablearray and popping a view controller manually. If I comment out the line [reviewUpload.images removeObject: self.reviewUploadImg] it doesn't give me the error but of course it's not useful for me like that. - (void) removeImage { debugLog(@"reviewUploadImg %@", self.reviewUploadImg); debugLog(@"reviewUpload %@", self.reviewUpload); debugLog(@"reviewUploadImg thumb %@", self.reviewUploadImg.thumb); [reviewUpload.images removeObject: self.reviewUploadImg]; [self.navigationController popViewControllerAnimated:TRUE]; }

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  • c++ builder TClientWinSocket simbol substitution

    - by Vlad
    I have the following problem. I have to send a text telegram over tcp/ip to a host device. Telegram should be terminated using 0x1A (CTRL-Z) character. But when I send it, host told me that there is a wrong symbol in the telegram. When I terminate a telegram with 32 (0x20) everything is ok. I look the transfered data using WireShark and I see that when I send 0x1A it is substituted with 0x16, when I send 32 (0x20) as a terminator it is somehow substituted with 0x1A. Can you explain it please. P.S. I am working on windows 7, using c++builder xe2. Thanks, Vladimir

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  • Using enums or a set of classes when I know I have a finite set of different options?

    - by devoured elysium
    Let's say I have defined the following class: public abstract class Event { public DateTime Time { get; protected set; } protected Event(DateTime time) { Time = time; } } What would you prefer between this: public class AsleepEvent : Event { public AsleepEvent(DateTime time) : base(time) { } } public class AwakeEvent : Event { public AwakeEvent(DateTime time) : base(time) { } } and this: public enum StateEventType { NowAwake, NowAsleep } public class StateEvent : Event { protected StateEventType stateType; public MealEvent(DateTime time, StateEventType stateType) : base(time) { stateType = stateType; } } and why? I am generally more inclined to the first option, but I can't explain why. Is it totally the same or are any advantages in using one instead of the other? Maybe with the first method its easier to add more "states", altough in this case I am 100% sure I will only want two states: now awake, and now asleep (they signal the moments when one awakes and one falls asleep).

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  • Posting within PHP and receiving only cookie

    - by faya
    Hello I have a question. It might be sound ridiculous, but let me explain what I want to accomplish. Right now I try to embed open source forum to by site and I want to leave forum and my site databases split. When my site users are logging in I want them also automatically be logged in to the forum system. For that I want to login within my PHP code after receiving username and password in post, but I don't know how I can get only cookies in response. I have found out that I can use curl_init(), curl_exec(), curl_close() functionality, but response from curl_exec returns whole response(page content, cookies, headers). Is there a way to receive only cookies? P.S. - If my design is totally wrong please give an advise how I can embed this functionality! I would be very thankful!

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  • preg_match basics question.

    - by Yo-L
    Hi all. Got some trouble with my preg_match. The code. $text = 'tel: 012 213 123. mobil: 0303 11234'; $regex_string = '/(tel|Tel|TEL)[\s|:]+(.+)[\.|\n]/'; preg_match($regex_string , $text, $match); And I get this result in $match[2] "012 213 123. mobil: 023 123 123" First question. I want the regex to stop at the .(dot) but it doesent. Can someone explain to why it isnt? Second question. preg_match uses () to get their match. Is it possible to skip the parentheses surrounding the different "Tel" and still get the same functionality? Thnx all stackoverflow is great :D

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  • AS3 How to center MC + change background color?

    - by Jennifer Heidelberg
    Hello everyone, I am quite new to AS3 and I have never worked with classes, so I am encountering a couple of problems. I'd like to center a movieclip, have it so that it doesn't scale. And then I'd like to add a background color that stays there no matter how I scale the browser. Can someone please explain me this in babysteps? Since I don't know how to implement a class and make it work with my fla. Thank you so much! J.

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  • does adding static library need xcode project of static library for linking?

    - by mirdad
    I have seen some static library projects in iOS.I see two different types of linking static library. 1)adding .a static library to new xcode project and its header files only. 2)adding .a static library to new xcode project and adding the xcode project through which static library has created. when I remove the the xcode project through which static library has created from the 2nd project, it gives error.I tried first approach for 2nd one.But it is not working. Can you please explain why it is differed? Will it be differed by the xcode versions we use? is The second approach for old xcode versions?

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  • NASM shift operators

    - by Hudson Worden
    How would you go about doing a bit shift in NASM on a register? I read the manual and it only seems to mention these operators , <<. When I try to use them NASM complains about the shift operator working on scalar values. Can you explain what a scalar value is and give an example of how to use and <<. Also, I thought there were a shr or shl operators. If they do exist can you give an example of how to use them? Thank you for your time.

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  • Objective C for Windows

    - by Luther Baker
    What would be the best way to write Objective-C on the Windows platform? Cygwin and gcc? Is there a way I can somehow integrate this into Visual Studio? Along those lines - are there any suggestions as to how to link in and use the Windows SDK for something like this. Its a different beast but I know I can write assembly and link in the Windows DLLs giving me accessibility to those calls but I don't know how to do this without googling and getting piecemeal directions. Is anyone aware of a good online or book resource to do or explain these kinds of things?

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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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  • HttpContext XML values in XSLT

    - by Siva
    Hi all. Please Help me out. In C# i set a context value as HttpContext.Current.Items["xmlcontentholder"] = xDoc.DocumentElement.FirstChild.OuterXml; and by processing XsltArgumentList i send it to an XSLT file: XsltArgumentList XsltArgs = new XsltArgumentList(); XsltArgs.AddParam("xmlcontentholder", "", "xmlcontent"); and i m transforming it xsltCompiledTrans.Transform(xPathNav, XsltArgs, stringWriter); In XSLT file i gave as <xsl:value-of select="$xmlcontentholder" /><br/>12<xsl:value-of select="msxsl:node-set($xmlcontentholder)/ROW[1]/value" />34 My output is <ROW><value>1</value><value>2</value></ROW> 1234 Please explain me on this problem..

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  • Hebbian learning

    - by Bane
    I have asked another question on Hebbian learning before, and I guess I got a good answer which I accepted, but, the problem is that I now realize that I've mistaken about Hebbian learning completely, and that I'm a bit confused. So, could you please explain how it can be useful, and what for? Because the way Wikipedia and some other pages describe it - it doesn't make sense! Why would we want to keep increasing the weight between the input and the output neuron if the fire together? What kind of problems can it be used to solve, because when I simulate it in my head, it certainly can't do the basic AND, OR, and other operations (say you initialize the weights at zero, the output neurons never fire, and the weights are never increased!)

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  • Why does concatenating a boolean value return an integer?

    - by joshhunt
    In python, you can concatenate boolean values, and it would return an integer. Example: >>> True True >>> True + True 2 >>> True + False 1 >>> True + True + True 3 >>> True + True + False 2 >>> False + False 0 Why? Why does this make sense? I understand that True is often represented as 1, whereas False is represented as 0, but that still does not explain how adding two values together of the same type returns a completely different type.

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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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  • Analyzing Python Code: Modulus Operator

    - by Bhubhu Hbuhdbus
    I was looking at some code in Python (I know nothing about Python) and I came across this portion: def do_req(body): global host, req data = "" s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((host, 80)) s.sendall(req % (len(body), body)) tmpdata = s.recv(8192) while len(tmpdata) > 0: data += tmpdata tmpdata = s.recv(8192) s.close() return data This is then called later on with body of huge size, as in over 500,000 bytes. This is sent to an Apache server that has the max request size on the default 8190 bytes. My question is what is happening at the "s.sendall()" part? Obviously the entire body cannot be sent at once and I'm guessing it is reduced by way of the modulus operator. I don't know how it works in Python, though. Can anyone explain? Thanks.

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  • functions in F# .. why is it not compiling

    - by Tanmoy
    Hi, I have written two versions of code. The first one works as expected and print "Hi". the second one gives me error that "block following this let is unfinished" 1st version #light let samplefn() = let z = 2 let z = z * 2 printfn "hi" samplefn() 2nd version #light let samplefn() = let z = 2 let z = z * 2 samplefn() Only difference is the printfn is absent in the second version. I am using Visual Studio 2010 as my IDE. I am very new to F# but this error seems very strange to me. I guess I am missing some very important concept. Please explain. Edit: Also if I do it outside the function I get error even with the first version of code. #light let z = 2 let z = z * 2 printfn "Error: Duplicate definition of value z"

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  • How to increase query speed without using full-text search?

    - by andre matos
    This is my simple query; By searching selectnothing I'm sure I'll have no hits. SELECT nome_t FROM myTable WHERE nome_t ILIKE '%selectnothing%'; This is the EXPLAIN ANALYZE VERBOSE Seq Scan on myTable (cost=0.00..15259.04 rows=37 width=29) (actual time=2153.061..2153.061 rows=0 loops=1) Output: nome_t Filter: (nome_t ~~* '%selectnothing%'::text) Total runtime: 2153.116 ms myTable has around 350k rows and the table definition is something like: CREATE TABLE myTable ( nome_t text NOT NULL, ) I have an index on nome_t as stated below: CREATE INDEX idx_m_nome_t ON myTable USING btree (nome_t); Although this is clearly a good candidate for Fulltext search I would like to rule that option out for now. This query is meant to be run from a web application and currently it's taking around 2 seconds which is obviously too much; Is there anything I can do, like using other index methods, to improve the speed of this query?

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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 add a VSTO project as a reference to a unit testing project?

    - by Mathias
    In order not to pollute my projects with unit tests, I like to create a separate project for my unit tests; I add a reference to the project under test in the unit tests project. However, this isn't working that well with my VSTO excel add-in projects: when I create a separate unit test project and go to Add Reference Projects, there is no project to pick. What I have done so far is Add Reference Browse, and pick the add-in dll from the debug folder. I have also run into issues from time to time with this, with the reference suddenly not working, requiring to remove/re-add the dll reference. Can anybody explain why a VSTO project doesn't show up as a regular project? And is there a better way to go about it than what I am doing presently?

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  • How to execute a large PHP Script ?

    - by atif089
    Well basically I may want to execute a script that may take as much as 1 hours as well. What I really want to do is Send SMS to my users using a third party API. So its basically like I supply my script with an array of phone numbers and fire the method to send SMS. However assuming it take 5 seconds to send 1 SMS and I want to send 1000 SMS which is roughly 1 - 2 hours. I can use set_time_limit() because I am on shared host. One way to do this is store numbers in a session and execute each SMS and use javascript to refresh that page until end. This way I need to keep my browser open and the execution will stop if my Internet Connection is disconnected. So, Is there any better way to do this ? Hope I am clear enough to explain what I want? I want to execute a large script that may take hours to execute without getting timeout.

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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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