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  • C++: Why don't I need to check if references are invalid/null?

    - by jbu
    Hi all, Reading http://www.cprogramming.com/tutorial/references.html, it says: In general, references should always be valid because you must always initialize a reference. This means that barring some bizarre circumstances (see below), you can be certain that using a reference is just like using a plain old non-reference variable. You don't need to check to make sure that a reference isn't pointing to NULL, and you won't get bitten by an uninitialized reference that you forgot to allocate memory for. My question is how do I know that the object's memory hasn't been freed/deleted AFTER you've initialized the reference. What it comes down to is that I can't take this advice on faith and I need a better explanation. Can anyone shed some light? Thanks, jbu

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  • Resharper: how to force introducing new private fields at the bottom of the class?

    - by Igor Brejc
    Resharper offers a very useful introduce and initialize field xxx action when you specify a new parameter in a constructor like: Constructor (int parameter) The only (minor) nuisance is that it puts the new field at the beginning of the class - and I'm a fan of putting private parts as far away as possible from the prying eyes of strangers ;). If, however, you already have some private fields in the class, Resharper will put the new field "correctly" (note the quotes, I don't want to start a flame war over this issue) next to those, even if they are at the end of the class. Is there a way to force Resharper to always put new fields at the end of the class? UPDATE: OK, I forgot to mention I know about the "Type Members Layout in Options" feature, but some concrete help on how to modify the template to achieve fields placement would be nice.

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  • C static variables and intialization

    - by yCalleecharan
    Hi, If I have a global static variable x like in this code #include <stdio.h> #include <stdio.h> static int x; int main(void) { DO SOMETHING WITH x HERE x++; } What will be difference if I opted to initialize x to a value first say as in static int x = 0; before entering "main"? In my first case where I didn't assign a value to x, does the compiler implicitly know that x is to be set to zero as it's a static variable? I heard that we can do this with static variables. Thanks a lot...

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  • To "null" or not to "null" my class's attributes

    - by Helper Method
    When I write a class in Java, I like to initialize the attributes which are set to a default value directly and attributes which are set by the caller in the constructor, something like this: public class Stack<E> { private List<E> list; private size = 0; public Stack(int initialCapacity) { list = new ArrayList<E>(initialCapacity); } // remainder omitted } Now suppose I have a Tree class: public class Tree<E> { private Node<E> root = null; // no constructor needed, remainder omitted } Shall I set the root attribute to null, to mark that it is set to null by default, or omit the null value?

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  • What is a good practice for handling SQL connections within a WCF call?

    - by Rising Star
    Suppose I want to create a (stateless) WCF service with three methods exposed on an endpoint: performSqlOperationA(), performSqlOperationB(), and performSqlOperationC(). Each method inserts data into a SQL database. The way I've seen things done at my office, each method would begin with code to initialize a SqlConnection object. Each method would end with code to safely dispose it. What is a good practice for coding these WCF methods so that the SqlConnection object is initialized and disposed in each method without having to do these things in each method? I know that I can have the connection initialized in the constructor for the class for the WCF methods, but I don't know about disposing it... The calls cannot be wrapped in a using block. One solution I'm familiar with is PostSharp, which allows me to set an attribute which causes specific code to automatically run at the beginning and end of each method call, but it would be greatly preferable to do this with only the .net framework.

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  • C# Generics Casting

    - by Nippysaurus
    Visual sutdio 2008 has the ability to automatically create unit test stubs. I have used this to create some basic unit tests, but I am confused by something: private class bla : BaseStoreItem { // } /// <summary> ///A test for StoreData ///</summary> public void StoreDataTestHelper<T>() where T : BaseStoreItem { FileStore<T> target = new FileStore<T>(); // TODO: Initialize to an appropriate value BaseStoreItem data = new bla(); target.StoreData(data); } [TestMethod()] public void StoreDataTest() { //Assert.Inconclusive("No appropriate type parameter is found to satisfies the type constraint(s) of T. " + // "Please call StoreDataTestHelper<T>() with appropriate type parameters."); StoreDataTestHelper<bla>(); } Why do I get "Error: Cannot convert type 'StorageUnitTests.FileStoreTest.bla' to 'T'" when T is type "bla"? I know "bla" is not a good function name, but its just an example.

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  • How to measure Silverlight or Flash control load time with Google Analytics

    - by ddehghan
    Hi everyone I have a simple silverlight page for for finding available domain names. This problem is equaly valid for a flash control as well. I use Google Analytics for monitoring the traffic. I would like to find out how long it take for users to download and render the Silverlight control. Once the java script on a page is loaded there should be a way to start a timer and then stop the timer once the Silverlight/flash control is loaded. Key points I would like to measure are: Time it takes to download the silverlight/flash control Time it takes to initialize the control Thanks

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  • Amazon EC2 multiple servers share session state

    - by Theofanis Pantelides
    Hi everyone, I have a bunch of EC2 servers that are load balanced. Some of the servers are not sharing session, and users keep getting logged in and out. How can I make all the server share the one session, possibly even using a partitionresolver solution public class PartitionResolver : System.Web.IPartitionResolver { private String[] partitions; public void Initialize() { // create the partition connection string table // web1, web2 partitions = new String[] { "192.168.1.1" }; } public String ResolvePartition(Object key) { String oHost = System.Web.HttpContext.Current.Request.Url.Host.ToLower().Trim(); if (oHost.StartsWith("10.0.0") || oHost.Equals("localhost")) return "tcpip=127.0.0.1:42424"; String sid = (String)key; // hash the incoming session ID into // one of the available partitions Int32 partitionID = Math.Abs(sid.GetHashCode()) % partitions.Length; return ("tcpip=" + partitions[partitionID] + ":42424"); } } -theo

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  • C++ containers on classes, returning pointers

    - by otneil
    Hello, I'm having some trouble to find the best way to accomplish what I have in mind due to my inexperience. I have a class where I need to a vector of objects. So my first question will be: is there any problem having this: vector< AnyType container* and then on the constructor initialize it with new (and deleting it on the destructor)? Another question is: if this vector is going to store objects, shouldn't it be more like vector< AnyTipe* so they could be dynamically created? In that case how would I return an object from a method and how to avoid memory leaks (trying to use only STL)?

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  • Multiple levels of 'collection.defaultdict' in Python

    - by Morlock
    Thanks to some great folks on SO, I discovered the possibilities offered by collections.defaultdict, notably in readability and speed. I have put them to use with success. Now I would like to implement three levels of dictionaries, the two top ones being defaultdict and the lowest one being int. I don't find the appropriate way to do this. Here is my attempt: from collections import defaultdict d = defaultdict(defaultdict) a = [("key1", {"a1":22, "a2":33}), ("key2", {"a1":32, "a2":55}), ("key3", {"a1":43, "a2":44})] for i in a: d[i[0]] = i[1] Now this works, but the following, which is the desired behavior, doesn't: d["key4"]["a1"] + 1 I suspect that I should have declared somewhere that the second level defaultdict is of type int, but I didn't find where or how to do so. The reason I am using defaultdict in the first place is to avoid having to initialize the dictionary for each new key. Any more elegant suggestion? Thanks pythoneers!

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  • How do I add text to curved image?

    - by miki123
    $config['source_image'] = '/path/to/image/mypic.jpg'; $config['wm_text'] = 'Copyright 2006 - John Doe'; $config['wm_type'] = 'text'; $config['wm_font_path'] = './system/fonts/texb.ttf'; $config['wm_font_size'] = '16'; $config['wm_font_color'] = 'ffffff'; $config['wm_vrt_alignment'] = 'bottom'; $config['wm_hor_alignment'] = 'center'; $config['wm_padding'] = '20'; $this->image_lib->initialize($config); $this->image_lib->watermark(); This is water mark code in php, it is working fine when we add text to curve image like mug image, the letter is not overlap the curved image how can we overcome?

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  • WSAT Security tab error for Custom Role provider

    - by shesb
    I have created custome Membership Role and Profile provider using INGRES db. Now I can see my IngresMembership and IngresRole provider in the Provider tab(Select a different provider for each feature (advanced) ) of WSAT but when I clik on security tab I get this error: "There is a problem with your selected data store. This can be caused by an invalid server name or credentials, or by insufficient permission. It can also be caused by the role manager feature not being enabled. Click the button below to be redirected to a page where you can choose a new data store. The following message may help in diagnosing the problem: Object reference not set to an instance of an object." What am I missing? Do I need to add code for all override methods for Role provider? I have just written code for the Initialize and GetRolesForUser functions. Thanks

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  • Weird behavior in referring to global variable. Is this a bug in javascript? Surely it isn't!

    - by Chandan .
    Consider the following piece of code. <html> <body> <script> var x = 5; //globally declared function showX() { alert("x="+x); //trying to display global value var x=10; //trying to create and initialize a local x } </script> <input type = "button" value="Show X" onclick="showX()"> </body> </html> The alert statement shows 'x=undefined'. And doesn't print the global value of x as expected. An equivalent java code would display 5! So, is it a bug? If not then how does one explain that behavior?

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  • Why in Objective-C, we use self = [super init] instead of just [super init]?

    - by ????
    In a book, I saw that if a subclass is overriding a superclass's method, we may have self = [super init]; First, is this supposed to be done in the subclass's init method? Second, I wonder why the call is not just [super init]; ? I mean, at the time of calling init, the memory is allocated by alloc already (I think by [Foobar alloc] where Foobar is the subclass's name. So can't we just call [super init] to initialize the member variables? Why do we have to get the return value of init and assign to self? I mean, before calling [super init], self should be pointing to a valid memory allocation chuck... so why assigning something to self again? (if assigning, won't [super init] just return self's existing value?)

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  • Balanced Search Tree Query, Asymtotic Analysis..

    - by AGeek
    Hi, The situation is as follows:- We have n number and we have print them in sorted order. We have access to balanced dictionary data structure, which supports the operations serach, insert, delete, minimum, maximum each in O(log n) time. We want to retrieve the numbers in sorted order in O(n log n) time using only the insert and in-order traversal. The answer to this is:- Sort() initialize(t) while(not EOF) read(x) insert(x,t); Traverse(t); Now the query is if we read the elements in time "n" and then traverse the elements in "log n"(in-order traversal) time,, then the total time for this algorithm (n+logn)time, according to me.. Please explain the follow up of this algorithm for the time calculation.. How it will sort the list in O(nlogn) time?? Thanks.

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  • Design question - loading info from DB

    - by eriks
    I need to build a class that will represent a row in some table in DB (lets say the table is 'Subscriber' and so is the class). I can have the class Subscriber which constructor receives the Objectkey of subscriber, retrieves info from DB and initializes its members. I add another class - SubscriberLoader which have a static method 'LoadSubscriber'. This method will receive the subscriber objectkey, retrieve info from DB, crate a Subscriber object and initialize its members. Subscriber constructor will be private and SubscirberLoader will be friend class of Subscriber - this way, client could build a Subscriber only using the loader. which of the two in better? any other suggestions?

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  • ReportViewer datadinding (WPF)

    - by user512150
    I have a rdlc file and I try to show it using report viewer control in WPF. My DataSource is called 'OfficeDataSet' and DataSet used in report is called 'Address'. I try to initialize report viewer (I put it in WindowsFormsHost) like this: private void PrepareReport() { reportDataSource = new ReportDataSource(); officeDataSet = new OfficeDataSet(); adapter = new AddressTableAdapter(); adapter.Fill(officeDataSet.Address); reportDataSource.Name = "OfficeDataSet_Address"; reportDataSource.Value = officeDataSet.Address; viewerInstance.LocalReport.DataSources.Add(reportDataSource); viewerInstance.LocalReport.ReportEmbeddedResource = "WpfApplication1.Reports.TestReport.rdlc"; viewerInstance.Location = new System.Drawing.Point(0, 0); viewerInstance.RefreshReport(); } but I got the message "A data source instance has not been supplied for the data source 'Address'". Anybody know what can be wrong with this code? (I'm totally new in WPF and Reporting Services).

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  • How to Prevent an Applet from Unloading across web pages?

    - by Francis Shanahan
    I have a large applet that takes some 40 seconds to initialize (cabs are cached so ignore download time for this question). The issue is, if the user goes to Page A which launches the applet (single window) and then navigates to page B, the applet is unloaded. If the user goes back to Page A, they incur the 40 seconds init time once again. I'd like to be able to launch the applet, incurring the 40 seconds init time once and only once. The applet needs to reside inside a single browser window (the same window as my web application). In other words, I cannot launch the applet in a popup. Does anyone have any creative ideas around how to prevent the applet unloading?

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  • The type{0} does not support direct content - WPF / XAML

    - by Levo
    Hi there: I defined in my code two classes: a "Person" class with public "Age" and "Name" property, and a "People" class that inherits from Generic.List(of T). The code for People class is as followed: Public Class People Inherits Collections.Generic.List(Of Person) ... End Class What I want to achieve is to directly initialize the People class, and add individual Person to it in XAML, i.e.: <local:People x:Key="Familty"> <local:Person Age="11" Name="John" /> <local:Person Age="12" Name="John2" /> ... </local:People> But I keep getting an error in XAML saying: The type 'People' does not support direct content. Any idea as for how to solve this problem? Thank you very much!

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  • Write to a binary file?

    - by rick irby
    Here is data structure w/ variables: struct Part_record { char id_no[3]; int qoh; string desc; double price: }; --- (Using "cin" to input data) --- Part_record null_part = {" ", 0," ",0.0}; --- --- file.seekg( -(long)sizeof(Part_record), ios::cur); file.write( ( char *)&part, sizeof(Part_record) ); The three variables, qoh, Id_no & price, write out correctly, but the "desc" variable is not right. Do I need to initialize Part_record some other way? It should be 20 characters in length. If you have enough info here, pls share your advice,thanks.

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  • ActiveRecord :through to set default values on through table.

    - by Dmitriy Likhten
    I would like to set a default value in a has_many through association. Lets say I have three models: People Friends Dogs A person can request that a dog becomes their friend. So a person would create an association where friends has an active column = false. User has_many :friends has_many :dogs, :through => :friends Now when I assign a dog to a user User.find(1).dogs << dog The friends table has null in the active column. My friends model is defined as Friend def initialize(args = {}) super(args) active = false end yet this does not work because the friend object is never created. Do I have to manually create one?

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  • Ruby Koans 202: Why does the correct answer give a syntax error?

    - by hlh
    I'm working through the about_classes.rb file in the Ruby Koans, and have hit a brick wall with the "inside_a_method_self_refers_to_the_containing_object" test. Here's the code: class Dog7 attr_reader :name def initialize(initial_name) @name = initial_name end def get_self self end def to_s __ end def inspect "<Dog named '#{name}'>" end end def test_inside_a_method_self_refers_to_the_containing_object fido = Dog7.new("Fido") fidos_self = fido.get_self assert_equal <Dog named 'Fido'>, fidos_self end So, I'm trying to make the first half of the assert_equal evaluate to the second half (fidos_self). When I work it out in irb, fidos_self returns <Dog named 'Fido'>, but I keep receiving a syntax error for that answer. I've seen this similar post: Ruby Koans: Where are the quotes in this return value?, but his solution (putting fido instead of <Dog named 'Fido'>) causes my rake to abort, saying the stack level is too deep. This is driving me nuts. What am I missing here?

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  • RS-232 confusion under C++

    - by rock
    What's the problem in given code? Why it is not showing the output for rs232 when we connect it by the d-9 connector with the short of pin number 2 & 3 in that? #include <bios.h> #include <conio.h> #define COM1 0 #define DATA_READY 0x100 #define SETTINGS ( 0x80 | 0x02 | 0x00 | 0x00) int main(void) { int in, out, status; bioscom(0, SETTINGS, COM1); /*initialize the port*/ cprintf("Data sent to you: "); while (1) { status = bioscom(3, 0, COM1); /*wait until get a data*/ if (status & DATA_READY) if ((out = bioscom(2, 0, COM1) & 0x7F) != 0) /*input a data*/ putch(out); if (kbhit()) { if ((in = getch()) == 27) /* ASCII of Esc*/ break; bioscom(1, in, COM1); /*output a data*/ } } return 0; }

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  • Set The Progress Bar Over 100% C#

    - by PhaDaPhunk
    its my first time using a ProgressBar in c#. The idea is to use the ProgressBar as an health bar in a simple game. The thing is I think the bar's maximum value is 100% but i would like to give it a higher value like let's say 1000% or, not sure if it's possible, give the bar an integer value instead of a percentage. progressBar1.Increment(100); This is where I initialize the health to 100points. Even if I use this syntax: progressBar1.Increment(1000); And I subtract : progressBar1.Increment(-25); The player is loosing 1/4 of is life as if he only had 100 Health Points. Any idea how I could change the maximum Bar value? Thanks in advance.

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  • How do I assign a value from params, or session, whichever exists?

    - by irkenInvader
    What is the "Rails-way" or the "Ruby-way" of doing the following: In my controller, I'm creating and instance of an Options class. It will be initialized with information in the params hash if the params hash exists. Otherwise, it will check the sessions hash for the information. Finally, it will initialize with defaults if neither params nor session has the data it needs. Here is how I'm doing it now (it works fine, but it seems a little ugly): if params[:cust_options] @options = CustomOptions.new( params[:cust_options] ) else if session[:cust_options @options = CustomOptions.new( session[:cust_options] ) else @options = CustomOptions.new end end session[:cust_options] = @options.to_hash Like I said, everything is working fine, I'm just looking for a more idiomatically Ruby way of writing this block of code.

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