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  • Basic Custom String Class for C++

    - by wdow88
    Hey all, I'm working on building my own string class with very basic functionality. I am having difficulty understand what is going on with the basic class that I have define, and believe there is some sort of error dealing with the scope occurring. When I try to view the objects I created, all the fields are described as (obviously bad pointer). Also, if I make the data fields public or build an accessor method, the program crashes. For some reason the pointer for the object is 0xccccccccc which points to no where. How can a I fix this? Any help/comments are much appreciated. //This is a custom string class, so far the only functions are //constructing and appending #include<iostream> using namespace std; class MyString1 { public: MyString1() { //no arg constructor char *string; string = new char[0]; string[0] ='\0'; std::cout << string; size = 1; } //constructor receives pointer to character array MyString1(char* chars) { int index = 0; //Determine the length of the array while (chars[index] != NULL) index++; //Allocate dynamic memory on the heap char *string; string = new char[index+1]; //Copy the contents of the array pointed by chars into string, the char array of the object for (int ii = 0; ii < index; ii++) string[ii] = chars[ii]; string[index+1] = '\0'; size = index+1; } MyString1 append(MyString1 s) { //determine new size of the appended array and allocate memory int newsize = s.size + size; MyString1 MyString2; char *newstring; newstring = new char[newsize+1]; int index = 0; //load the first string into the array while (string[index] != NULL) { newstring[index] = string[index]; index++; } //load the second string while (s.string[index] != NULL) { newstring[index] = s.string[index]; index++; } //null terminate newstring[newsize+1] = '\0'; delete string; //generate the object for return MyString2.string=newstring; MyString2.size=newsize; return MyString2; } private: char *string; int size; }; int main() { MyString1 string1; MyString1 string2("Hello There"); MyString1 string3("Buddy"); string2.append(string3); return 0; }

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  • SQL Server 2008: If Multiple Values Set In Other Mutliple Values Set

    - by AJH
    In SQL, is there anyway to accomplish something like this? This is based off a report built in SQL Server Report Builder, where the user can specify multiple text values as a single report parameter. The query for the report grabs all of the values the user selected and stores them in a single variable. I need a way for the query to return only records that have associations to EVERY value the user specified. -- Assume there's a table of Elements with thousands of entries. -- Now we declare a list of properties for those Elements to be associated with. create table #masterTable ( ElementId int, Text varchar(10) ) insert into #masterTable (ElementId, Text) values (1, 'Red'); insert into #masterTable (ElementId, Text) values (1, 'Coarse'); insert into #masterTable (ElementId, Text) values (1, 'Dense'); insert into #masterTable (ElementId, Text) values (2, 'Red'); insert into #masterTable (ElementId, Text) values (2, 'Smooth'); insert into #masterTable (ElementId, Text) values (2, 'Hollow'); -- Element 1 is Red, Coarse, and Dense. Element 2 is Red, Smooth, and Hollow. -- The real table is actually much much larger than this; this is just an example. -- This is me trying to replicate how SQL Server Report Builder treats -- report parameters in its queries. The user selects one, some, all, -- or no properties from a list. The written query treats the user's -- selections as a single variable called @Properties. -- Example scenario 1: User only wants to see Elements that are BOTH Red and Dense. select e.* from Elements e where (@Properties) --ideally a set containing only Red and Dense in (select Text from #masterTable where ElementId = e.Id) --ideally a set containing only Red, Coarse, and Dense --Both Red and Dense are within Element 1's properties (Red, Coarse, Dense), so Element 1 gets returned, but not Element 2. -- Example scenario 2: User only wants to see Elements that are BOTH Red and Hollow. select e.* from Elements e where (@Properties) --ideally a set containing only Red and Hollow in (select Text from #masterTable where ElementId = e.Id) --Both Red and Hollow are within Element 2's properties (Red, Smooth, Hollow), so Element 2 gets returned, but not Element 1. --Example Scenario 3: User only picked the Red option. select e.* from Elements e where (@Properties) --ideally a set containing only Red in (select Text from #masterTable where ElementId = e.Id) --Red is within both Element 1 and Element 2's properties, so both Element 1 and Element 2 get returned. The above syntax doesn't actually work because SQL doesn't seem to allow multiple values on the left side of the "in" comparison. Error that returns: Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression. Am I even on the right track here? Sorry if the example looks long-winded or confusing.

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  • Delphi Unit local variables - how to make each instance unique?

    - by Justin
    Ok, this, I'm sure is something simple that is easy to do. The problem : I've inherited scary spaghetti code and am slowly trying to better it when new features need adding - generally when a refactor makes adding the new feature neater. I've got a bunch of code I'm packing into a single unit which, in different places in the application, controls the same physical thing in the outside world. The control appears in several places in the application and operates slightly differently in each instance. What I've done is to create a unit with all of the features I need which I can simply drop, as a frame, into each form that requires it. Each form then uses the unit's interface methods to customise the behaviour for each instance. The problem within the problem : In the unit in question (the frame) I have a variable declared in the IMPLEMENTATION section - local to the unit. I also have a procedure, declared in the TYPE section which takes an argument and assigns that argument to the local variable in question - each form passes a unique variable to each instance of the frame/unit. What I want it to do is for each instance of the frame to keep its own version of that variable, different from the others, and use that to define how it operates. What seems to be happening, however, is that all instances are using the same value, even if I explicitly pass each instance a different variable. ie: Unit FlexibleUnit; interface uses //the uses stuff type TFlexibleUnit=class(TFrame) //declarations including procedure makeThisInstanceX(passMeTheVar:integer); private // public // end; implementation uses //the uses var myLocalVar; procedure makeThisInstanceX(passMeTheVar:integer); begin myLocalVar:=passMeTheVar; end; //other procedures using myLocalVar //etc to the end; Now somewhere in another Form I've dropped this Frame onto the Design pane, sometimes two of these frames on one Form, and have it declared in the proper places, etc. Each is unique in that : ThisFlexibleUnit : TFlexibleUnit; ThatFlexibleUnit : TFlexibleUnit; and when I do a: ThisFlexibleUnit.makeThisInstanceX(var1); //want to behave in way "var1" ThatFlexibleUnit.makeThisInstanceX(var2); //want to behave in way "var2" it seems that they both share the same variable "myLocalVar". Am I doing this wrong, in principle? If this is the correct method then it's a matter of debugging what I have (which is too huge to post) but if this is not correct in principle then is there a way to do what I am suggesting? Thanks in advance, Stack Overflow - you guys (and gals!) are legendary.

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  • MATLAB image corner coordinates & referncing to cell arrays

    - by James
    Hi, I am having some problems comparing the elements in different cell arrays. The context of this problem is that I am using the bwboundaries function in MATLAB to trace the outline of an image. The image is of a structural cross section and I am trying to find if there is continuity throughout the section (i.e. there is only one outline produced by the bwboundaries command). Having done this and found where the is more than one section traced (i.e. it is not continuous), I have used the cornermetric command to find the corners of each section. The code I have is: %% Define the structural section as a binary matrix (Image is an I-section with the web broken) bw(20:40,50:150) = 1; bw(160:180,50:150) = 1; bw(20:60,95:105) = 1; bw(140:180,95:105) = 1; Trace = bw; [B] = bwboundaries(Trace,'noholes'); %Traces the outer boundary of each section L = length(B); % Finds number of boundaries if L > 1 disp('Multiple boundaries') % States whether more than one boundary found end %% Obtain perimeter coordinates for k=1:length(B) %For all the boundaries perim = B{k}; %Obtains perimeter coordinates (as a 2D matrix) from the cell array end %% Find the corner positions C = cornermetric(bw); Areacorners = find(C == max(max(C))) % Finds the corner coordinates of each boundary [rowindexcorners,colindexcorners] = ind2sub(size(Newgeometry),Areacorners) % Convert corner coordinate indexes into subcripts, to give x & y coordinates (i.e. the same format as B gives) %% Put these corner coordinates into a cell array Cornerscellarray = cell(length(rowindexcorners),1); % Initialises cell array of zeros for i =1:numel(rowindexcorners) Cornerscellarray(i) = {[rowindexcorners(i) colindexcorners(i)]}; %Assigns the corner indicies into the cell array %This is done so the cell arrays can be compared end for k=1:length(B) %For all the boundaries found perim = B{k}; %Obtains coordinates for each perimeter Z = perim; % Initialise the matrix containing the perimeter corners Sectioncellmatrix = cell(length(rowindexcorners),1); for i =1:length(perim) Sectioncellmatrix(i) = {[perim(i,1) perim(i,2)]}; end for i = 1:length(perim) if Sectioncellmatrix(i) ~= Cornerscellarray Sectioncellmatrix(i) = []; %Gets rid of the elements that are not corners, but keeps them associated with the relevent section end end end This creates an error in the last for loop. Is there a way I can check whether each cell of the array (containing an x and y coordinate) is equal to any pair of coordinates in cornercellarray? I know it is possible with matrices to compare whether a certain element matches any of the elements in another matrix. I want to be able to do the same here, but for the pair of coordinates within the cell array. The reason I don't just use the cornercellarray cell array itself, is because this lists all the corner coordinates and does not associate them with a specific traced boundary.

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  • Displaying a notification when bluetooth is disconnected - Android

    - by Ryan T
    I am trying to create a program that will display a notification to the user if a Blue tooth device suddenly comes out of range from my Android device. I currently have the following code but no notification is displayed. I was wondering if it was possible I shouldn't use ACTION_ACL_DISCONNECTED because I believe the bluetooth stack would be expecting packets that state a disconnect is requested. My requirements state that the bluetooth device will disconnect without warning. Thank you for any assistance! BluetoothNotification.java: //This is where the notification is created. import android.app.Activity; import android.app.Notification; import android.app.NotificationManager; import android.app.PendingIntent; import android.content.Context; import android.content.Intent; import android.os.Bundle; import android.app.Activity; import android.app.Notification; import android.app.NotificationManager; import android.app.PendingIntent; import android.content.Context; import android.content.Intent; import android.os.Bundle; public class BluetoothNotification extends Activity { public static final int NOTIFICATION_ID = 1; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); /** Define configuration for our notification */ int icon = R.drawable.logo; CharSequence tickerText = "This is a sample notification"; long when = System.currentTimeMillis(); Context context = getApplicationContext(); CharSequence contentTitle = "Sample notification"; CharSequence contentText = "This notification has been generated as a result of BT Disconnecting"; Intent notificationIntent = new Intent(this, BluetoothNotification.class); PendingIntent contentIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0); /** Initialize the Notification using the above configuration */ final Notification notification = new Notification(icon, tickerText, when); notification.setLatestEventInfo(context, contentTitle, contentText, contentIntent); /** Retrieve reference from NotificationManager */ String ns = Context.NOTIFICATION_SERVICE; final NotificationManager mNotificationManager = (NotificationManager) getSystemService(ns); mNotificationManager.notify(NOTIFICATION_ID, notification); finish(); } } Snippet from OnCreate: //Located in Controls.java IntentFilter filter1 = new IntentFilter(BluetoothDevice.ACTION_ACL_DISCONNECTED); this.registerReceiver(mReceiver, filter1); Snippet from Controls.java: private final BroadcastReceiver mReceiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { String action = intent.getAction(); BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE); if (BluetoothDevice.ACTION_ACL_DISCONNECTED.equals(action)) { //Device has disconnected NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE); } } };

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  • Displaying pic for user through a question's answer

    - by bgadoci
    Ok, I am trying to display the profile pic of a user. The application I have set up allows users to create questions and answers (I am calling answers 'sites' in the code) the view in which I am trying to do so is in the /views/questions/show.html.erb file. It might also be of note that I am using the Paperclip gem. Here is the set up: Associations Users class User < ActiveRecord::Base has_many :questions, :dependent => :destroy has_many :sites, :dependent => :destroy has_many :notes, :dependent => :destroy has_many :likes, :through => :sites , :dependent => :destroy has_many :pics, :dependent => :destroy has_many :likes, :dependent => :destroy end Questions class Question < ActiveRecord::Base has_many :sites, :dependent => :destroy has_many :notes, :dependent => :destroy has_many :likes, :dependent => :destroy belongs_to :user end Answers (sites) class Site < ActiveRecord::Base belongs_to :question belongs_to :user has_many :notes, :dependent => :destroy has_many :likes, :dependent => :destroy has_attached_file :photo, :styles => { :small => "250x250>" } end Pics class Pic < ActiveRecord::Base has_attached_file :profile_pic, :styles => { :small => "100x100" } belongs_to :user end The /views/questions/show.html.erb is rendering the partial /views/sites/_site.html.erb which is calling the Answer (site) with: <% div_for site do %> <%=h site.description %> <% end %> I have been trying to do things like: <%=image_tag site.user.pic.profile_pic.url(:small) %> <%=image_tag site.user.profile_pic.url(:small) %> etc. But that is obviously wrong. My error directs me to the Questions#show action so I am imagining that I need to define something in there but not sure what. Is is possible to call the pic given the current associations, placement of the call, and if so what Controller additions do I need to make, and what line of code will call the pic? UPDATE: Here is the QuestionsController#show code: def show @question = Question.find(params[:id]) @sites = @question.sites.all(:select => "sites.*, SUM(likes.like) as like_total", :joins => "LEFT JOIN likes AS likes ON likes.site_id = sites.id", :group => "sites.id", :order => "like_total DESC") respond_to do |format| format.html # show.html.erb format.xml { render :xml => @question } end end

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  • Selecting and Populating a unFocused tab.

    - by Deyon
    I'm having a problem displaying data from a function to text box within a tab. If you run the code and click "Select Tab 2 and Fill..." I get an error; "TypeError: Error #1009: Cannot access a property or method of a null object reference." I'm guessing this is because "Tab 2" is/was not rendered yet. Now if I run the code, select "Tab 2" then select "Tab 1" and click "Select Tab 2 and Fill..." it works the way I would like. Dose any one know a way around this problem. ----Full Flex 4/Flash Builder Code just copy paste---- <?xml version="1.0" encoding="utf-8"?> <s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" xmlns:mx="library://ns.adobe.com/flex/halo" creationComplete=" "> <fx:Script> <![CDATA[ public function showtab2():void { mytextbox.text="I made it!"; tn.selectedIndex=1; } ]]> </fx:Script> <fx:Declarations> <!-- Place non-visual elements (e.g., services, value objects) here --> </fx:Declarations> <mx:Panel title="TabNavigator Container Example" height="90%" width="90%" paddingTop="10" paddingLeft="10" paddingRight="10" paddingBottom="10"> <mx:Label width="100%" color="blue" text="Select the tabs to change the panel."/> <mx:TabNavigator id="tn" width="100%" height="100%"> <!-- Define each panel using a VBox container. --> <mx:VBox label="Panel 1"> <mx:Label text="TabNavigator container panel 1"/> <mx:Button label="Select Tab 2 and Fill with Text" click="showtab2()"/> </mx:VBox> <mx:VBox label="Panel 2"> <mx:Label text="TabNavigator container panel 2"/> <s:TextInput id="mytextbox" /> </mx:VBox> </mx:TabNavigator> <mx:HBox> </mx:HBox> </mx:Panel> </s:WindowedApplication>

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  • Java Best Practice for type resolution at runtime.

    - by Brian
    I'm trying to define a class (or set of classes which implement the same interface) that will behave as a loosely typed object (like JavaScript). They can hold any sort of data and operations on them depend on the underlying type. I have it working in three different ways but none seem ideal. These test versions only allow strings and integers and the only operation is add. Adding integers results in the sum of the integer values, adding strings concatenates the strings and adding an integer to a string converts the integer to a string and concatenates it with the string. The final version will have more types (Doubles, Arrays, JavaScript-like objects where new properties can be added dynamically) and more operations. Way 1: public interface DynObject1 { @Override public String toString(); public DynObject1 add(DynObject1 d); public DynObject1 addTo(DynInteger1 d); public DynObject1 addTo(DynString1 d); } public class DynInteger1 implements DynObject1 { private int value; public DynInteger1(int v) { value = v; } @Override public String toString() { return Integer.toString(value); } public DynObject1 add(DynObject1 d) { return d.addTo(this); } public DynObject1 addTo(DynInteger1 d) { return new DynInteger1(d.value + value); } public DynObject1 addTo(DynString1 d) { return new DynString1(d.toString()+Integer.toString(value)); } } ...and similar for DynString1 Way 2: public interface DynObject2 { @Override public String toString(); public DynObject2 add(DynObject2 d); } public class DynInteger2 implements DynObject2 { private int value; public DynInteger2(int v) { value = v; } @Override public String toString() { return Integer.toString(value); } public DynObject2 add(DynObject2 d) { Class c = d.getClass(); if(c==DynInteger2.class) { return new DynInteger2(value + ((DynInteger2)d).value); } else { return new DynString2(toString() + d.toString()); } } } ...and similar for DynString2 Way 3: public class DynObject3 { private enum ObjectType { Integer, String }; Object value; ObjectType type; public DynObject3(Integer v) { value = v; type = ObjectType.Integer; } public DynObject3(String v) { value = v; type = ObjectType.String; } @Override public String toString() { return value.toString(); } public DynObject3 add(DynObject3 d) { if(type==ObjectType.Integer && d.type==ObjectType.Integer) { return new DynObject3(Integer.valueOf(((Integer)value).intValue()+((Integer)value).intValue())); } else { return new DynObject3(value.toString()+d.value.toString()); } } } With the if-else logic I could use value.getClass()==Integer.class instead of storing the type but with more types I'd change this to use a switch statement and Java doesn't allow switch to use Classes. Anyway... My question is what is the best way to go about something thike this?

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  • MFC: Reading entire file to buffer...

    - by deostroll
    I've meddled with some code but I am unable to read the entire file properly...a lot of junk gets appended to the output. How do I fix this? // wmfParser.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include "wmfParser.h" #include <cstring> #ifdef _DEBUG #define new DEBUG_NEW #endif // The one and only application object CWinApp theApp; using namespace std; int _tmain(int argc, TCHAR* argv[], TCHAR* envp[]) { int nRetCode = 0; // initialize MFC and print and error on failure if (!AfxWinInit(::GetModuleHandle(NULL), NULL, ::GetCommandLine(), 0)) { // TODO: change error code to suit your needs _tprintf(_T("Fatal Error: MFC initialization failed\n")); nRetCode = 1; } else { // TODO: code your application's behavior here. CFile file; CFileException exp; if( !file.Open( _T("c:\\sample.txt"), CFile::modeRead, &exp ) ){ exp.ReportError(); cout<<'\n'; cout<<"Aborting..."; system("pause"); return 0; } ULONGLONG dwLength = file.GetLength(); cout<<"Length of file to read = " << dwLength << '\n'; /* BYTE* buffer; buffer=(BYTE*)calloc(dwLength, sizeof(BYTE)); file.Read(buffer, 25); char* str = (char*)buffer; cout<<"length of string : " << strlen(str) << '\n'; cout<<"string from file: " << str << '\n'; */ char str[100]; file.Read(str, sizeof(str)); cout << "Data : " << str <<'\n'; file.Close(); cout<<"File was closed\n"; //AfxMessageBox(_T("This is a test message box")); system("pause"); } return nRetCode; }

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  • Template function as a template argument

    - by Kos
    I've just got confused how to implement something in a generic way in C++. It's a bit convoluted, so let me explain step by step. Consider such code: void a(int) { // do something } void b(int) { // something else } void function1() { a(123); a(456); } void function2() { b(123); b(456); } void test() { function1(); function2(); } It's easily noticable that function1 and function2 do the same, with the only different part being the internal function. Therefore, I want to make function generic to avoid code redundancy. I can do it using function pointers or templates. Let me choose the latter for now. My thinking is that it's better since the compiler will surely be able to inline the functions - am I correct? Can compilers still inline the calls if they are made via function pointers? This is a side-question. OK, back to the original point... A solution with templates: void a(int) { // do something } void b(int) { // something else } template<void (*param)(int) > void function() { param(123); param(456); } void test() { function<a>(); function<b>(); } All OK. But I'm running into a problem: Can I still do that if a and b are generics themselves? template<typename T> void a(T t) { // do something } template<typename T> void b(T t) { // something else } template< ...param... > // ??? void function() { param<SomeType>(someobj); param<AnotherType>(someotherobj); } void test() { function<a>(); function<b>(); } I know that a template parameter can be one of: a type, a template type, a value of a type. None of those seems to cover my situation. My main question is hence: How do I solve that, i.e. define function() in the last example? (Yes, function pointers seem to be a workaround in this exact case - provided they can also be inlined - but I'm looking for a general solution for this class of problems).

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  • How do you return a pointer to a base class with a virtual function?

    - by Nick Sweet
    I have a base class called Element, a derived class called Vector, and I'm trying to redefine two virtual functions from Element in Vector. //element.h template <class T> class Element { public: Element(); virtual Element& plus(const Element&); virtual Element& minus(const Element&); }; and in another file //Vector.h #include "Element.h" template <class T> class Vector: public Element<T> { T x, y, z; public: //constructors Vector(); Vector(const T& x, const T& y = 0, const T& z =0); Vector(const Vector& u); ... //operations Element<T>& plus(const Element<T>& v) const; Element<T>& minus(const Element<T>& v) const; ... }; //sum template <class T> Element<T>& Vector<T>::plus(const Element<T>& v) const { Element<T>* ret = new Vector((x + v.x), (y + v.y), (z + v.z)); return *ret; } //difference template <class T> Element<T>& Vector<T>::minus(const Element<T>& v) const { Vector<T>* ret = new Vector((x - v.x), (y - v.y), (z - v.z)); return *ret; } but I always get error: 'const class Element' has no member named 'getx' So, can I define my virtual functions to take Vector& as an argument instead, or is there a way for me to access the data members of Vector through a pointer to Element? I'm still fairly new to inheritance polymorphism, fyi.

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  • Problem separating C++ code in header, inline functions and code.

    - by YuppieNetworking
    Hello all, I have the simplest code that I want to separate in three files: Header file: class and struct declarations. No implementations at all. Inline functions file: implementation of inline methods in header. Code file: normal C++ code for more complicated implementations. When I was about to implement an operator[] method, I couldn't manage to compile it. Here is a minimal example that shows the same problem: Header (myclass.h): #ifndef _MYCLASS_H_ #define _MYCLASS_H_ class MyClass { public: MyClass(const int n); virtual ~MyClass(); double& operator[](const int i); double operator[](const int i) const; void someBigMethod(); private: double* arr; }; #endif /* _MYCLASS_H_ */ Inline functions (myclass-inl.h): #include "myclass.h" inline double& MyClass::operator[](const int i) { return arr[i]; } inline double MyClass::operator[](const int i) const { return arr[i]; } Code (myclass.cpp): #include "myclass.h" #include "myclass-inl.h" #include <iostream> inline MyClass::MyClass(const int n) { arr = new double[n]; } inline MyClass::~MyClass() { delete[] arr; } void MyClass::someBigMethod() { std::cout << "Hello big method that is not inlined" << std::endl; } And finally, a main to test it all: #include "myclass.h" #include <iostream> using namespace std; int main(int argc, char *argv[]) { MyClass m(123); double x = m[1]; m[1] = 1234; cout << "m[1]=" << m[1] << endl; x = x + 1; return 0; } void nothing() { cout << "hello world" << endl; } When I compile it, it says: main.cpp:(.text+0x1b): undefined reference to 'MyClass::MyClass(int)' main.cpp:(.text+0x2f): undefined reference to 'MyClass::operator[](int)' main.cpp:(.text+0x49): undefined reference to 'MyClass::operator[](int)' main.cpp:(.text+0x65): undefined reference to 'MyClass::operator[](int)' However, when I move the main method to the MyClass.cpp file, it works. Could you guys help me spot the problem? Thank you.

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  • Correct usage of socket_select().

    - by Mark Tomlin
    What is the correct way to use socket_select within PHP to send and receive data? I have a connection to the server that allows for both TCP & UDP packet connections, I am utilizing both. Within these connections I'm both sending and receiving packets on the same port, but the TCP packet will be sent on one port (29999) and UDP will be sent on another port (30000). The transmission type will be that of AF_INET. The IP address will be loopback 127.0.0.1. I have many questions on how to create a socket connection within this scenario. For example, is it better to use socket_create_pair to make the connection, or use just socket_create followed by socket_connect, and then implement socket_select? There is a chance that no data will be sent from the server to the client, and it is up to the client to maintain the connection. This will be done by utilizing the time out function within the socket_select call. Should no data be sent within the time limit, the socket_select function will break and a keep alive packet can then be sent. The following script is of the client. // Create $TCP = socket_create(AF_INET, SOCK_STREAM, SOL_TCP); $UDP = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP); // Misc $isAlive = TRUE; $UDPPort = 30000; define('ISP_ISI', 1); // Connect socket_connect($TCP, '127.0.0.1', 29999); socket_connect($UDP, '127.0.0.1', $UDPPort); // Construct Parameters $recv = array($TCP, $UDP); $null = NULL; // Make The Packet to Send. $packet = pack('CCCxSSxCSa16a16', 44, ISP_ISI, 1, $UDPPort, 0, '!', 0, 'AdminPass', 'SocketSelect'); // Send ISI (InSim Init) Packet socket_write($TCP, $packet); /* Main Program Loop */ while ($isAlive == TRUE) { // Socket Select $sock = socket_select($recv, $null, $null, 5); // Check Status if ($sock === FALSE) $isAlive = FALSE; # Error else if ($sock > 0) # How does one check to find what socket changed? else # Something else happed, don't know what as it's not in the documentation, Could this be our timeout getting tripped? }

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  • Specializating a template function that takes a universal reference parameter

    - by David Stone
    How do I specialize a template function that takes a universal reference parameter? foo.hpp: template<typename T> void foo(T && t) // universal reference parameter foo.cpp template<> void foo<Class>(Class && class) { // do something complicated } Here, Class is no longer a deduced type and thus is Class exactly; it cannot possibly be Class &, so reference collapsing rules will not help me here. I could perhaps create another specialization that takes a Class & parameter (I'm not sure), but that implies duplicating all of the code contained within foo for every possible combination of rvalue / lvalue references for all parameters, which is what universal references are supposed to avoid. Is there some way to accomplish this? To be more specific about my problem in case there is a better way to solve it: I have a program that can connect to multiple game servers, and each server, for the most part, calls everything by the same name. However, they have slightly different versions for a few things. There are a few different categories that these things can be: a move, an item, etc. I have written a generic sort of "move string to move enum" set of functions for internal code to call, and my server interface code has similar functions. However, some servers have their own internal ID that they communicate with, some use strings, and some use both in different situations. Now what I want to do is make this a little more generic. I want to be able to call something like ServerNamespace::server_cast<Destination>(source). This would allow me to cast from a Move to a std::string or ServerMoveID. Internally, I may need to make a copy (or move from) because some servers require that I keep a history of messages sent. Universal references seem to be the obvious solution to this problem. The header file I'm thinking of right now would expose simply this: namespace ServerNamespace { template<typename Destination, typename Source> Destination server_cast(Source && source); } And the implementation file would define all legal conversions as template specializations.

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  • zlib gzgets extremely slow?

    - by monkeyking
    I'm doing stuff related to parsing huge globs of textfiles, and was testing what input method to use. There is not much of a difference using c++ std::ifstreams vs c FILE, According to the documentation of zlib, it supports uncompressed files, and will read the file without decompression. I'm seeing a difference from 12 seconds using non zlib to more than 4 minutes using zlib.h This I've tested doing multiple runs, so its not a disk cache issue. Am I using zlib in some wrong way? thanks #include <zlib.h> #include <cstdio> #include <cstdlib> #include <fstream> #define LENS 1000000 size_t fg(const char *fname){ fprintf(stderr,"\t-> using fgets\n"); FILE *fp =fopen(fname,"r"); size_t nLines =0; char *buffer = new char[LENS]; while(NULL!=fgets(buffer,LENS,fp)) nLines++; fprintf(stderr,"%lu\n",nLines); return nLines; } size_t is(const char *fname){ fprintf(stderr,"\t-> using ifstream\n"); std::ifstream is(fname,std::ios::in); size_t nLines =0; char *buffer = new char[LENS]; while(is. getline(buffer,LENS)) nLines++; fprintf(stderr,"%lu\n",nLines); return nLines; } size_t iz(const char *fname){ fprintf(stderr,"\t-> using zlib\n"); gzFile fp =gzopen(fname,"r"); size_t nLines =0; char *buffer = new char[LENS]; while(0!=gzgets(fp,buffer,LENS)) nLines++; fprintf(stderr,"%lu\n",nLines); return nLines; } int main(int argc,char**argv){ if(atoi(argv[2])==0) fg(argv[1]); if(atoi(argv[2])==1) is(argv[1]); if(atoi(argv[2])==2) iz(argv[1]); }

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  • Trouble passing a string as a SQLite ExecSQL command

    - by Hackbrew
    I keep getting the ERROR: near "PassWord": syntax error when trying to execute the ExecSQL() statement. The command looks good in the output of the text file. In fact, I copied & pasted the command directly into SQLite Database Browser and the commend executed properly. Here's the code that's producing the error: procedure TForm1.Button1Click(Sender: TObject); var i, iFieldSize: integer; sFieldName, sFieldType, sFieldList, sExecSQL: String; names: TStringList; f1: Textfile; begin //Open Source table - Table1 has 8 fields but has only two different field types ftString and Boolean Table1.TableName:= 'PWFile'; Table1.Open; //FDConnection1.ExecSQL('drop table PWFile'); sFieldList := ''; names := TStringList.Create; for i := 0 to Table1.FieldCount - 1 do begin sFieldName := Table1.FieldDefList.FieldDefs[i].Name; sFieldType := GetEnumName(TypeInfo(TFieldType),ord(Table1.FieldDefList.FieldDefs[i].DataType)); iFieldSize := Table1.FieldDefList.FieldDefs[i].Size; if sFieldType = 'ftString' then sFieldType := 'NVARCHAR' + '(' + IntToStr(iFieldSize) + ')'; if sFieldType = 'ftBoolean' then sFieldType := 'INTEGER'; names.Add(sFieldName + ' ' + sFieldType); if sFieldList = '' then sFieldList := sFieldName + ' ' + sFieldType else sFieldList := sFieldList + ', ' + sFieldName + ' ' + sFieldType; end; ListBox1.Items.Add(sFieldList); sExecSQL := 'create table IF NOT EXISTS PWFile (' + sFieldList + ')'; // 08/18/2014 - Entered this to log the SQLite FDConnection1.ExecSQL Command to a file AssignFile(f1, 'C:\Users\Test User\Documents\SQLite_Command.txt'); Rewrite(f1); Writeln(f1, sExecSQL); { insert code here that would require a Flush before closing the file } Flush(f1); { ensures that the text was actually written to file } CloseFile(f1); FDConnection1.ExecSQL(sFieldList); Table1.Close; end; Here's the actual command that gets executed: create table IF NOT EXISTS PWFile (PassWord NVARCHAR(10), PassName NVARCHAR(10), Dept NVARCHAR(10), Active NVARCHAR(1), Admin INTEGER, Shred INTEGER, Reports INTEGER, Maintain INTEGER)

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  • Getting 404 when attempting to POST file to Google Cloud Storage from service account

    - by klactose
    I'm wondering if anyone can tell me the proper syntax & formatting for a service account to send a POST Object to bucket request? I'm attempting it programmatically using the HttpComponents library. I manage to get a token from my GoogleCredential, but every time I construct the POST request, I get: HTTP/1.1 403 Forbidden <?xml version='1.0' encoding='UTF-8'?><Error><Code>AccessDenied</Code><Message>Access denied.</Message><Detailsbucket-name</Details></Error The Google documentation that describes the request methods, mentions posting using html forms, but I'm hoping that wasn't suggesting the ONLY way to get the job done. I know that HttpComponents has a way to explicitly create form data by using UrlEncodedFormEntity, but it doesn't support multipart data. Which is why I went with using the MultipartEntity class. My code is below: MultipartEntity entity = new MultipartEntity( HttpMultipartMode.BROWSER_COMPATIBLE ); String token = credential.getAccessToken(); entity.addPart("Authorization", new StringBody("OAuth " + token)); String date = formatDate(new Date()); entity.addPart("Date", new StringBody(date)); entity.addPart("Content-Encoding", new StringBody("UTF-8")); entity.addPart("Content-Type", new StringBody("multipart/form-data")); entity.addPart("bucket", new StringBody(bucket)); entity.addPart("key", new StringBody("fileName")); entity.addPart("success_action_redirect", new StringBody("/storage")); File uploadFile = new File("pathToFile"); FileBody fileBody = new FileBody(uploadFile, "text/xml"); entity.addPart("file", fileBody); httppost.setEntity(entity); System.out.println("Posting URI = "+httppost.toString()); HttpResponse response = client.execute(httppost); HttpEntity resp_entity = response.getEntity(); As I mentioned, I am able to get an actual token, so I'm pretty sure the problem is in how I've formed the request as opposed to not being properly authenticated. Keep in mind: This is being performed by a service account. Which means that it does have Read/Write access Thanks for reading, and I appreciate any help!

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  • Writing a managed wrapper for unmanaged (C++) code - custom types/structs

    - by Bobby
    faacEncConfigurationPtr FAACAPI faacEncGetCurrentConfiguration( faacEncHandle hEncoder); I'm trying to come up with a simple wrapper for this C++ library; I've never done more than very simple p/invoke interop before - like one function call with primitive arguments. So, given the above C++ function, for example, what should I do to deal with the return type, and parameter? FAACAPI is defined as: #define FAACAPI __stdcall faacEncConfigurationPtr is defined: typedef struct faacEncConfiguration { int version; char *name; char *copyright; unsigned int mpegVersion; unsigned long bitRate; unsigned int inputFormat; int shortctl; psymodellist_t *psymodellist; int channel_map[64]; } faacEncConfiguration, *faacEncConfigurationPtr; AFAIK this means that the return type of the function is a reference to this struct? And faacEncHandle is: typedef struct { unsigned int numChannels; unsigned long sampleRate; ... SR_INFO *srInfo; double *sampleBuff[MAX_CHANNELS]; ... double *freqBuff[MAX_CHANNELS]; double *overlapBuff[MAX_CHANNELS]; double *msSpectrum[MAX_CHANNELS]; CoderInfo coderInfo[MAX_CHANNELS]; ChannelInfo channelInfo[MAX_CHANNELS]; PsyInfo psyInfo[MAX_CHANNELS]; GlobalPsyInfo gpsyInfo; faacEncConfiguration config; psymodel_t *psymodel; /* quantizer specific config */ AACQuantCfg aacquantCfg; /* FFT Tables */ FFT_Tables fft_tables; int bitDiff; } faacEncStruct, *faacEncHandle; So within that struct we see a lot of other types... hmm. Essentially, I'm trying to figure out how to deal with these types in my managed wrapper? Do I need to create versions of these types/structs, in C#? Something like this: [StructLayout(LayoutKind.Sequential)] struct faacEncConfiguration { uint useTns; ulong bitRate; ... } If so then can the runtime automatically "map" these objects onto eachother? And, would I have to create these "mapped" types for all the types in these return types/parameter type hierarchies, all the way down until I get to all primitives? I know this is a broad topic, any advice on getting up-to-speed quickly on what I need to learn to make this happen would be very much appreciated! Thanks!

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  • Any way to allow classes implementing IEntity and downcast to have operator == comparisons?

    - by George Mauer
    Basically here's the issue. All entities in my system are identified by their type and their id. new Customer() { Id = 1} == new Customer() {Id = 1}; new Customer() { Id = 1} != new Customer() {Id = 2}; new Customer() { Id = 1} != new Product() {Id = 1}; Pretty standard scenario. Since all Entities have an Id I define an interface for all entities. public interface IEntity { int Id { get; set;} } And to simplify creation of entities I make public abstract class BaseEntity<T> : where T : IEntity { int Id { get; set;} public static bool operator ==(BaseEntity<T> e1, BaseEntity<T> e2) { if (object.ReferenceEquals(null, e1)) return false; return e1.Equals(e2); } public static bool operator !=(BaseEntity<T> e1, BaseEntity<T> e2) { return !(e1 == e2); } } where Customer and Product are something like public class Customer : BaseEntity<Customer>, IEntity {} public class Product : BaseEntity<Product>, IEntity {} I think this is hunky dory. I think all I have to do is override Equals in each entity (if I'm super clever, I can even override it only once in the BaseEntity) and everything with work. So now I'm expanding my test coverage and find that its not quite so simple! First of all , when downcasting to IEntity and using == the BaseEntity< override is not used. So what's the solution? Is there something else I can do? If not, this is seriously annoying. Upadate It would seem that there is something wrong with my tests - or rather with comparing on generics. Check this out [Test] public void when_created_manually_non_generic() { // PASSES! var e1 = new Terminal() {Id = 1}; var e2 = new Terminal() {Id = 1}; Assert.IsTrue(e1 == e2); } [Test] public void when_created_manually_generic() { // FAILS! GenericCompare(new Terminal() { Id = 1 }, new Terminal() { Id = 1 }); } private void GenericCompare<T>(T e1, T e2) where T : class, IEntity { Assert.IsTrue(e1 == e2); } Whats going on here? This is not as big a problem as I was afraid, but is still quite annoying and a completely unintuitive way for the language to behave. Update Update Ah I get it, the generic implicitly downcasts to IEntity for some reason. I stand by this being unintuitive and potentially problematic for my Domain's consumers as they need to remember that anything happening within a generic method or class needs to be compared with Equals()

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  • PHP 5.3: Late static binding doesn't work for properties when defined in parent class while missing in child class

    - by DavidPesta
    Take a look at this example, and notice the outputs indicated. <?php class Mommy { protected static $_data = "Mommy Data"; public static function init( $data ) { static::$_data = $data; } public static function showData() { echo static::$_data . "<br>"; } } class Brother extends Mommy { } class Sister extends Mommy { } Brother::init( "Brother Data" ); Sister::init( "Sister Data" ); Brother::showData(); // Outputs: Sister Data Sister::showData(); // Outputs: Sister Data ?> My understanding was that using the static keyword would refer to the child class, but apparently it magically applies to the parent class whenever it is missing from the child class. (This is kind of a dangerous behavior for PHP, more on that explained below.) I have the following two things in mind for why I want to do this: I don't want the redundancy of defining all of the properties in all of the child classes. I want properties to be defined as defaults in the parent class and I want the child class definition to be able to override these properties wherever needed. The child class needs to exclude properties whenever the defaults are intended, which is why I don't define the properties in the child classes in the above example. However, if we are wanting to override a property at runtime (via the init method), it will override it for the parent class! From that point forward, child classes initialized earlier (as in the case of Brother) unexpectedly change on you. Apparently this is a result of child classes not having their own copy of the static property whenever it isn't explicitly defined inside of the child class--but instead of throwing an error it switches behavior of static to access the parent. Therefore, is there some way that the parent class could dynamically create a property that belongs to the child class without it appearing inside of the child class definition? That way the child class could have its own copy of the static property and the static keyword can refer to it properly, and it can be written to take into account parent property defaults. Or is there some other solution, good, bad, or ugly?

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  • How do I code a loop for my echo statements?

    - by ggg
    <?php defined('_JEXEC') or die('Restricted access'); $db =& JFactory::getDBO(); $query0 = "SELECT * FROM `#__chesspositions` WHERE . . . . ."; //echo $query0; $db->setQuery($query0); $ginfo = $db->loadObjectList(); //echo $ginfo[0]; echo $db->getErrorMsg(); if(empty($ginfo)){ echo "<center><h2 style='color:navy'>No game found, we apologize</h2></center>"; }else{ $query1= "SELECT * FROM `#__chessmoves` WHERE Id='".$ginfo[0]->MoveDataId."'"; $db->setQuery($query1); echo $db->getErrorMsg(); $gmove = $db->loadObjectList(); } //define array; //how do I code a foreach loop (or any other type of loop) here? //I'm having trouble properly defining the array and structuring the syntax. echo "[Event \"".$ginfo[0]->Event."\"]\n"; echo "[Site \"".$ginfo[0]->Site."\"]\n"; echo "[Date \"".$ginfo[0]->Date."\"]\n"; echo "[Round \"".$ginfo[0]->Round."\"]\n"; echo "[White \"".$ginfo[0]->White."\"]\n"; echo "[Black \"".$ginfo[0]->Black."\"]\n"; echo "[Result \"".$ginfo[0]->Result."\"]\n"; echo "[ECO \"".$ginfo[0]->ECO."\"]\n"; echo "[WhiteElo \"".$ginfo[0]->WhiteElo."\"]\n"; echo "[BlackElo \"".$ginfo[0]->BlackElo."\"]\n"; echo "[Annotator \"".$ginfo[0]->Annotator."\"]\n"; echo "[SetUp \"".$ginfo[0]->SetUp."\"]\n"; echo $gmove[0]->MoveData; ?>

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  • howto parse struct to C++ dll from C#

    - by Nerds Rule
    I am trying to call a function in a unmanaged C++ dll. It has this prototype: [DllImport("C:\\Program Files\\MySDK\\VSeries.dll", EntryPoint = "BII_Send_Index_Template_MT" )] internal unsafe static extern Int32 BII_Send_Index_Template_MT(IntPtr pUnitHandle, ref BII_Template template, Int32 option, Boolean async); BII_Template template = new BII_Template(); error_code = BII_Send_Index_Template_MT(pUnitHandle, ref template, option, false); I is how I define the BII_Template struct in C#: public unsafe struct BII_Template { public ulong id; public ulong employee_id; public ulong password; public byte sensor_version; public byte template_version; public fixed char name[16]; public byte finger; public byte admin_level; public byte schedule; public byte security_thresh; public fixed byte noise_level[18]; public byte corramb; public byte reference_x; public byte reference_y; public fixed byte ihcore[3]; public fixed byte ivcore[3]; public byte temp_xoffset; public byte temp_yoffset; public byte index; public fixed byte inphase[5500]; }; It build and when I run it the dll return error_code = "The record checksum is invalid." I assume that I am using the ref keyword in a wrong way or the size of some of the elements in the struct is wrong. ----- EDIT ------------ Here is the struct in C++: typedef struct { unsigned long id; unsigned long employee_id; unsigned long password; unsigned char sensor_version; unsigned char template_version; char name[16]; unsigned char finger; unsigned char admin_level; unsigned char schedule; unsigned char security_thresh; unsigned char noise_level[18]; unsigned char corramb ; unsigned char reference_x ; unsigned char reference_y ; unsigned char ihcore[NUM_CORE]; unsigned char ivcore[NUM_CORE]; unsigned char temp_xoffset; unsigned char temp_yoffset; unsigned char index; unsigned char inphase[PACKED_ARRAY_SIZE]; } BII_Template;

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  • Primary language - C++/Qt, C#, Java?

    - by Airjoe
    I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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  • Why does VerticalScrollBarVisibility not work in a style in Silverlight?

    - by Edward Tanguay
    VerticalScrollBarVisibility works when I define it inline like this: <UserControl x:Class="TestScrollBar.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"> <UserControl.Resources> <Style TargetType="TextBox" x:Key="EditListContainerContentMultiLineTwoColumn"> <Setter Property="AcceptsReturn" Value="True"/> <Setter Property="Width" Value="400"/> <Setter Property="Height" Value="300"/> <Setter Property="IsReadOnly" Value="False"/> <Setter Property="Margin" Value="0 0 0 20"/> <Setter Property="HorizontalAlignment" Value="Left"/> <Setter Property="TextWrapping" Value="Wrap" /> </Style> </UserControl.Resources> <Grid x:Name="LayoutRoot" Background="White" Margin="10"> <StackPanel HorizontalAlignment="Left"> <TextBox Text="this is a test" Style="{StaticResource EditListContainerContentMultiLineTwoColumn}" VerticalScrollBarVisibility="Auto" /> </StackPanel> </Grid> </UserControl> But when I put VerticalScrollBarVisibility in a style, it shows me a blank screen: <UserControl x:Class="TestScrollBar.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"> <UserControl.Resources> <Style TargetType="TextBox" x:Key="EditListContainerContentMultiLineTwoColumn"> <Setter Property="VerticalScrollBarVisibility" Value="Auto"/> <Setter Property="AcceptsReturn" Value="True"/> <Setter Property="Width" Value="400"/> <Setter Property="Height" Value="300"/> <Setter Property="IsReadOnly" Value="False"/> <Setter Property="Margin" Value="0 0 0 20"/> <Setter Property="HorizontalAlignment" Value="Left"/> <Setter Property="TextWrapping" Value="Wrap" /> </Style> </UserControl.Resources> <Grid x:Name="LayoutRoot" Background="White" Margin="10"> <StackPanel HorizontalAlignment="Left"> <TextBox Text="this is a test" Style="{StaticResource EditListContainerContentMultiLineTwoColumn}" /> </StackPanel> </Grid> </UserControl> In WPF it works works fine. How can I get VerticalScrollBarVisibility to work in a style?

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  • Java DriverManager Always Assigns My Driver

    - by JGB146
    I am writing a driver to act as a wrapper around two separate MySQL connections (to distributed databases). Basically, the goal is to enable interaction with my driver for all applications instead of requiring the application to sort out which database holds the desired data. Most of the code for this is in place, but I'm having a problem in that when I attempt to create connections via the MySQL Driver, the DriverManager is returning an instance of my driver instead of the MySQL Driver. I'd appreciate any tips on what could be causing this and what could be done to fix it! Below is a few relevant snippets of code. I can provide more, but there's a lot, so I'd need to know what else you want to see. First, from MyDriver.java: public MyDriver() throws SQLException { DriverManager.registerDriver(this); } public Connection connect(String url, Properties info) throws SQLException { try { return new MyConnection(info); } catch (Exception e) { return null; } } public boolean acceptsURL(String url) throws SQLException { if (url.contains("jdbc:jgb://")) { return true; } return false; } It is my understanding that this acceptsURL function will dictate whether or not the DriverManager deems my driver a suitable fit for a given URL. Hence it should only be passing connections from my driver if the URL contains "jdbc:jgb://" right? Here's code from MyConnection.java: Connection c1 = null; Connection c2 = null; /** *Constructors */ public DDBSConnection (Properties info) throws SQLException, Exception { info.list(System.out); //included for testing Class.forName("com.mysql.jdbc.Driver").newInstance(); String url1 = "jdbc:mysql://server1.com/jgb"; String url2 = "jdbc:mysql://server2.com/jgb"; this.c1 = DriverManager.getConnection( url1, info.getProperty("username"), info.getProperty("password")); this.c2 = DriverManager.getConnection( url2, info.getProperty("username"), info.getProperty("password")); } And this tells me two things. First, the info.list() call confirms that the correct user and password are being sent. Second, because we enter an infinite loop, we see that the DriverManager is providing new instances of my connection as matches for the mysql URLs instead of the desired mysql driver/connection. FWIW, I have separately tested implementations that go straight to the mysql driver using this exact syntax (al beit only one at a time), and was able to successfully interact with each database individually from a test application outside of my driver.

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