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  • Make an ActiveX control work without a form?

    - by Earlz
    We are using Topaz Signature pads. They provide their APIs in the from of an ActiveX control which is to be put on a Winform control. Well, the way our project will work we do not want to have a form(at least not visible). We just want for the signature ActiveX control to get an image in the background. static AxSigPlus sig = new AxSIGPLUSLib.AxSigPlus(); public static void Begin() { ((System.ComponentModel.ISupportInitialize)(sig)).BeginInit(); sig.Name = "sig"; sig.Location = new System.Drawing.Point(0, 0); sig.Size = new System.Drawing.Size(0, 0); sig.Enabled = true; sig.TabletState = 1; //error here sig.SigCompressionMode = 0; } Ok so I get an error at the marked line. The exception is Exception of type 'System.Windows.Forms.AxHost+InvalidActiveXStateException' was thrown. What do I do to solve this problem? Would it just be easier to create a new hidden form and put the control on it so it's invisible?

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  • AES Encryption Java Invalid Key length

    - by wuntee
    I am trying to create an AES encryption method, but for some reason I keep getting a 'java.security.InvalidKeyException: Key length not 128/192/256 bits'. Here is the code: public static SecretKey getSecretKey(char[] password, byte[] salt) throws NoSuchAlgorithmException, InvalidKeySpecException{ SecretKeyFactory factory = SecretKeyFactory.getInstance("PBEWithMD5AndDES"); // NOTE: last argument is the key length, and it is 256 KeySpec spec = new PBEKeySpec(password, salt, 1024, 256); SecretKey tmp = factory.generateSecret(spec); SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES"); return(secret); } public static byte[] encrypt(char[] password, byte[] salt, String text) throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, InvalidKeyException, InvalidParameterSpecException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException{ SecretKey secret = getSecretKey(password, salt); Cipher cipher = Cipher.getInstance("AES"); // NOTE: This is where the Exception is being thrown cipher.init(Cipher.ENCRYPT_MODE, secret); byte[] ciphertext = cipher.doFinal(text.getBytes("UTF-8")); return(ciphertext); } Can anyone see what I am doing wrong? I am thinking it may have something to do with the SecretKeyFactory algorithm, but that is the only one I can find that is supported on the end system I am developing against. Any help would be appreciated. Thanks.

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  • Integers not properly returned from a property list (plist) array in Objective-C

    - by Gaurav
    In summary, I am having a problem where I read what I expect to be an NSNumber from an NSArray contained in a property list and instead of getting a number such as '1', I get what looks to be a memory address (i.e. '61879840'). The numbers are clearly correct in the property list. Below is my process for creating the property list and reading it back. Creating the property list I have created a simple Objective-C property list with arrays of integers within one root array: <array> <array> <integer>1</integer> <integer>2</integer> </array> <array> <integer>1</integer> <integer>2</integer> <integer>5</integer> </array> ... more arrays with integers ... </array> The arrays are NSArray objects and the integers are NSNumber objects. The property list has been created and serialized using the following code: // factorArray is an NSArray that contains NSArrays of NSNumbers as described above // serialize and compress factorArray as a property list, Factors-bin.plist NSString *error; NSString *rootPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0]; NSString *plistPath = [rootPath stringByAppendingPathComponent:@"Factors-bin.plist"]; NSData *plistData = [NSPropertyListSerialization dataFromPropertyList:factorArray format:NSPropertyListBinaryFormat_v1_0 errorDescription:&error]; Inspecting the created plist, all values and types are correct. Reading the property list The property list is read in as Data and then converted to an NSArray: NSString *path = [[NSBundle mainBundle] pathForResource:@"Factors" ofType:@"plist"]; NSData *plistData = [[NSData alloc] initWithContentsOfFile:path]; NSPropertyListFormat format; NSString *error = nil; NSArray *factorData = (NSArray *)[NSPropertyListSerialization propertyListFromData:plistData mutabilityOption:NSPropertyListImmutable format:&format errorDescription:&error]; Cycling through factorData to see what it contains is where I see the erroneous integers: for (int i = 0; i < 10; i++) { NSArray *factorList = (NSArray *)[factorData objectAtIndex:i]; NSLog(@"Factors of %d\n", i + 1); for (int j = 0; j < [factorList count]; j++) { NSLog(@" %d\n", (NSNumber *)[factorList objectAtIndex:j]); } } I see all the correct number of values, but the values themselves are incorrect, i.e.: Factors of 3 61879840 (should be 1) 61961200 (should be 3) Factors of 4 61879840 (should be 1) 61943472 (should be 2) 61943632 (should be 4) Factors of 5 61879840 (should be 1) 61943616 (should be 5)

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  • Re-using Buttons in WPF

    - by Alex Marshall
    I have a bunch of different objects that are commonly edited in the same TabControl using different DataTemplates, but I want each DataTemplate to have a common look and feel with Ok and Cancel buttons at the bottom right of each tab that will close the tab or save the content and then close the currently selected tab. What's the best way to place buttons on each tab ? Is there a way to do it without copying and pasting the buttons and stack panel across all of my data templates ?

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  • Programming Logic upgrading from VB6 to Vb.net

    - by KoolKabin
    Hi guys, I have been programming in vb6 for few time ago and i used open SQL Server connection and command objects to make database traansactions. I have been searching for similar approaches in vb.net too but not finding any starting point. How can we work similarly in vb.net application?

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  • How to Disable/Enable WYSIWYG editor in Magento 1.4

    - by latvian
    Hi When entering code in CMS static block(possible page as well) and in this code there is empty DIV tags such us: <a href="javascript:hide1(),show2(),hide3()"><div class="dropoff_button"></div></a> The DIV tags will be gone next time you open the block to edit. it will look as this <a href="javascript:hide1(),show2(),hide3()"> </a> without the div tags ...and saving again it modifies your code. I think it something to do with the 'show/hide editor'. By default it goes into the WYSIWYG editor, so when updating static block i don't see any other solution than 1."hide the editor' by clicking 'show/hide editor' 2.delete the old code from the editor 3. get code that doesn't miss the DIVs 4. Merge new code with code in 3 in some other editing software than magento 5. paste result in the magento editor, 6. Save Is this bug? What is your solution? Can i turn of WYSIWYG editor?

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  • 'object' undeclared <first use in this function>

    - by Mohit Deshpande
    I am using Winchain to develop on my Windows 7 machine. Here is my code: iPhoneTest.h #import <Foundation/Foundation.h> #import <UIKit/UIKit.h> @interface iPhoneTest : UIApplication { UITextView *textview; UIView *mainView; } @end iPhoneTest.m #import "iPhoneTest.h" #import <UIKit/UIKit.h> #import <Foundation/Foundation.h> #import <CoreFoundation/CoreFoundation.h> @implementation iPhoneTest -(void)applicationDidFinishLaunching:(id)unused { UIWindow *window; struct CGRect rect = [UIHardware fullScreenApplicationContentRect]; rect.origin.x = rect.origin.y = 0.0f; window = [[UIWindow alloc] initWithContentRect: rect]; mainView = [[UIView alloc] initWithFrame: rect]; textView = [[UITextView alloc] init]; [textView setEditable:YES]; [textView setTextSize:14]; [window orderFront: self]; [window makeKey: self]; [window _setHidden: NO]; [window setContentView: mainView]; [mainView addSubview:textView]; [textView setText:@"Hello World"]; } @end main.m #import <Foundation/Foundation.h> #import <UIKit/UIKit.h> #import "iPhoneTest.h" int main(int argc, char *argv[]) { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; int ret = UIApplicationMain(argc, argv, [iPhoneTest class]); [pool release]; return ret; } Makefile INFOPLIST_FILE=Info.plist SOURCES=\ main.m \ iPhoneTest.m CC=/usr/local/bin/arm-apple-darwin-gcc CFLAGS=-g -O2 -Wall LD=$(CC) LDFLAGS=-lobjc -framework CoreFoundation -framework Foundation -framework UIKit -framework LayerKit PRODUCT_NAME=iPhoneTest SRCROOT=/iphone-apps/iPhoneTest WRAPPER_NAME=$(PRODUCT_NAME).app EXECUTABLE_NAME=$(PRODUCT_NAME) SOURCES_ABS=$(addprefix $(SRCROOT)/,$(SOURCES)) INFOPLIST_ABS=$(addprefix $(SRCROOT)/,$(INFOPLIST_FILE)) OBJECTS=\ $(patsubst %.c,%.o,$(filter %.c,$(SOURCES))) \ $(patsubst %.cc,%.o,$(filter %.cc,$(SOURCES))) \ $(patsubst %.cpp,%.o,$(filter %.cpp,$(SOURCES))) \ $(patsubst %.m,%.o,$(filter %.m,$(SOURCES))) \ $(patsubst %.mm,%.o,$(filter %.mm,$(SOURCES))) OBJECTS_ABS=$(addprefix $(CONFIGURATION_TEMP_DIR)/,$(OBJECTS)) APP_ABS=$(BUILT_PRODUCTS_DIR)/$(WRAPPER_NAME) PRODUCT_ABS=$(APP_ABS)/$(EXECUTABLE_NAME) all: $(PRODUCT_ABS) $(PRODUCT_ABS): $(APP_ABS) $(OBJECTS_ABS) $(LD) $(LDFLAGS) -o $(PRODUCT_ABS) $(OBJECTS_ABS) $(APP_ABS): $(INFOPLIST_ABS) mkdir -p $(APP_ABS) cp $(INFOPLIST_ABS) $(APP_ABS)/ $(CONFIGURATION_TEMP_DIR)/%.o: $(SRCROOT)/%.m mkdir -p $(dir $@) $(CC) $(CFLAGS) $(CPPFLAGS) -c $< -o $@ clean: echo rm -f $(OBJECTS_ABS) echo rm -rf $(APP_ABS) When I try to compile it with make, I get iPhoneTest.m: In fucntion '-[iPhoneTest applicationDidFinishLaunching:]' iPhoneTest.m:15: error: 'testView' undeclared <first use in this function> iPhoneTest.m:15: error: <Each undeclared identifier is reported only once for each function it appears in> Can anyone spot the problem?

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  • OpenGl glutIdleFunc(void (*func)(void))

    - by PHENOMERICAN
    I'm trying to design very simple animation in OpenGL such as rotating and translating objects. In the red book, I found that using GLUT's glutIdleFunc() is okay for a simple animation. How many times does glutIdleFunc(...) call the function in one second? Thank you.

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  • Zend Form: How to pass parameters into the constructor?

    - by Andrew
    I'm trying to test my form. It will be constructing other objects, so I need a way to mock them. I tried passing them into the constructor... class Form_Event extends Zend_Form { public function __construct($options = null, $regionMapper = null) { $this->_regionMapper = $regionMapper; parent::__construct($options); } ...but I get an exception: Zend_Form_Exception: Only form elements and groups may be overloaded; variable of type "Mock_Model_RegionMapper_b19e528a" provided What am I doing wrong?

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  • Webservice returning 403 error

    - by user48408
    I'm wondering whether I'm receiving the 403 errors because there are too many attempted connections being made to the webservice. If this is the case how do I get around it? I've tried creating a new instance of InternalWebService each time and disposing of the old one but I get the same problem. I've disabled the firewall and the webservice is located locally at the moment. I beginning to think it may be a problem with the credentials but the control tree is populated via the webservice at some stage. If I browse to the webmethods in my browser I can run them all. I return an instance of the webservice from my login handler loginsession.cs: static LoginSession() { ... g_NavigatorWebService = new InternalWebService(); g_NavigatorWebService.Credentials = System.Net.CredentialCache.DefaultCredentials; ... } public static InternalWebService NavigatorWebService { get { return g_NavigatorWebService; } } I have a tree view control which uses the webservice to populate itself. IncidentTreeViewControl.cs: public IncidentTreeView() { InitializeComponent(); m_WebService = LoginSession.NavigatorWebService; ... } public void Populate() { m_WebService.BeginGetIncidentSummaryByCompany(new AsyncCallback(IncidentSummaryByClientComplete), null); m_WebService.BeginGetIncidentSummaryByDepartment(new AsyncCallback(IncidentSummaryByDepartmentComplete), null); ... } private void IncidentSummaryByClientComplete(IAsyncResult ar) { MyTypedDataSet data = m_WebService.EndGetIncidentSummaryByCompany(ar); //403 ..cont... } I'm getting the 403 on the last line.

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  • How to use delegate to perform callback between caller and web service helper class?

    - by codemonkie
    I have 2 classes A and B, where they belongs to the same namespace but resides in seperate files namely a.cs and b.cs, where class B essentially is a helper wrapping a web service call as follow: public class A { public A() // constructor { protected static B b = new B(); } private void processResult1(string result) { // come here when result is successful } private void processResult2(string result) { // come here when result is failed } static void main() { b.DoJobHelper(...); } } public class B { private com.nowhere.somewebservice ws; public B() { this.ws = new com.nowhere.somewebservice(); ws.JobCompleted += new JobCompletedEventHandler(OnCompleted); } void OnCompleted(object sender, JobCompletedEventArgs e) { string s = e.Result; Guid taskID = (Guid)e.UserState; switch (s) { case "Success": // Call processResult1(); break; case "Failed": // Call processResult2(); break; default: break; } } public void DoJobHelper() { Object userState = Guid.NewGuid(); ws.DoJob(..., userState); } } (1) I have seen texts on the net on using delegates for callbacks but failed to apply that to my case. All I want to do is to call the appropriate processResult() method upon OnCompleted() event, but dunno how to and where to declare the delegate: public delegate void CallBack(string s); (2) There is a sender object passed in to OnCompleted() but never used, did I miss anything there? Or how can I make good use of sender? Any helps appreciated.

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  • Parsing SQL in .NET

    - by Eli
    I'm trying to build a .NET Managed data provider and I need to be able to parse SQL commands. What are good, free (as in beer) objects to do this? - I haven't seen any standard .NET assemblies for this yet. Thanks, Eli.

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  • C++ scoping error

    - by Pat Murray
    I have the following code: #include "Student.h" #include "SortedList.h" using namespace std; int main() { // points to the sorted list object SortedList *list = new SortedList; //This is line 17 // array to hold 100 student objects Student create[100]; int num = 100000; // holds different ID numbers // fills an array with 100 students of various ID numbers for (Student &x : create) { x = new Student(num); num += 100; } // insert all students into the sorted list for (Student &x : create) list->insert(&x); delete list; return 0; } And I keep getting the compile time error: main.cpp: In function ‘int main()’: main.cpp:17: error: ‘SortedList’ was not declared in this scope main.cpp:17: error: ‘list’ was not declared in this scope main.cpp:17: error: expected type-specifier before ‘SortedList’ main.cpp:17: error: expected `;' before ‘SortedList’ main.cpp:20: error: ‘Student’ was not declared in this scope main.cpp:20: error: expected primary-expression before ‘]’ token main.cpp:20: error: expected `;' before ‘create’ main.cpp:25: error: expected `;' before ‘x’ main.cpp:31: error: expected primary-expression before ‘for’ main.cpp:31: error: expected `;' before ‘for’ main.cpp:31: error: expected primary-expression before ‘for’ main.cpp:31: error: expected `)' before ‘for’ main.cpp:31: error: expected `;' before ‘x’ main.cpp:34: error: type ‘<type error>’ argument given to ‘delete’, expected pointer main.cpp:35: error: expected primary-expression before ‘return’ main.cpp:35: error: expected `)' before ‘return’ My Student.cpp and SortedList.cpp files compile just fine. They both also include .h files. I just do not understand why I get an error on that line. It seems to be a small issue though. Any insight would be appreciated. UPDATE1: I originally had .h files included, but i changed it when trying to figure out the cause of the error. The error remains with the .h files included though. UPDATE2: SortedList.h #ifndef SORTEDLIST_H #define SORTEDLIST_H #include "Student.h" /* * SortedList class * * A SortedList is an ordered collection of Students. The Students are ordered * from lowest numbered student ID to highest numbered student ID. */ class SortedList { public: SortedList(); // Constructs an empty list. SortedList(const SortedList & l); // Constructs a copy of the given student object ~SortedList(); // Destructs the sorted list object const SortedList & operator=(const SortedList & l); // Defines the assignment operator between two sorted list objects bool insert(Student *s); // If a student with the same ID is not already in the list, inserts // the given student into the list in the appropriate place and returns // true. If there is already a student in the list with the same ID // then the list is not changed and false is returned. Student *find(int studentID); // Searches the list for a student with the given student ID. If the // student is found, it is returned; if it is not found, NULL is returned. Student *remove(int studentID); // Searches the list for a student with the given student ID. If the // student is found, the student is removed from the list and returned; // if no student is found with the given ID, NULL is returned. // Note that the Student is NOT deleted - it is returned - however, // the removed list node should be deleted. void print() const; // Prints out the list of students to standard output. The students are // printed in order of student ID (from smallest to largest), one per line private: // Since Listnodes will only be used within the SortedList class, // we make it private. struct Listnode { Student *student; Listnode *next; }; Listnode *head; // pointer to first node in the list static void freeList(Listnode *L); // Traverses throught the linked list and deallocates each node static Listnode *copyList(Listnode *L); // Returns a pointer to the first node within a particular list }; #endif #ifndef STUDENT_H #define STUDENT_H Student.h #ifndef STUDENT_H #define STUDENT_H /* * Student class * * A Student object contains a student ID, the number of credits, and an * overall GPA. */ class Student { public: Student(); // Constructs a default student with an ID of 0, 0 credits, and 0.0 GPA. Student(int ID); // Constructs a student with the given ID, 0 credits, and 0.0 GPA. Student(int ID, int cr, double grPtAv); // Constructs a student with the given ID, number of credits, and GPA.\ Student(const Student & s); // Constructs a copy of another student object ~Student(); // Destructs a student object const Student & operator=(const Student & rhs); // Defines the assignment operator between two student objects // Accessors int getID() const; // returns the student ID int getCredits() const; // returns the number of credits double getGPA() const; // returns the GPA // Other methods void update(char grade, int cr); // Updates the total credits and overall GPA to take into account the // additions of the given letter grade in a course with the given number // of credits. The update is done by first converting the letter grade // into a numeric value (A = 4.0, B = 3.0, etc.). The new GPA is // calculated using the formula: // // (oldGPA * old_total_credits) + (numeric_grade * cr) // newGPA = --------------------------------------------------- // old_total_credits + cr // // Finally, the total credits is updated (to old_total_credits + cr) void print() const; // Prints out the student to standard output in the format: // ID,credits,GPA // Note: the end-of-line is NOT printed after the student information private: int studentID; int credits; double GPA; }; #endif

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  • Microsoft.ACE.OLEDB.12.0 has not been Registered" Error

    - by brohjoe
    I'm getting a "The OLE DB provider "Microsoft.ACE.OLEDB.12.0 has not been registered" error. I have the data objects library downloaded and I have "Microsoft Office 12.0 Access database engine Object Library" selected. I'm running the Windows Vista 32-bit operating system. Any ideas would be greatly appreciated.

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  • InvalidCastException in DataGridView

    - by Max Yaffe
    (Using VS 2010 Beta 2 - .Net 4.0 B2 Rel) I have a class, MyTable, derived from BindingList where S is a struct. S is made up of several other structs, for example: public class MyTable<S>:BindingList<S> where S: struct { ... } public struct MyStruct { public MyReal r1; public MyReal r2; public MyReal R1 {get{...} set{...}} public MyReal R2 {get{...} set{...}} ... } public struct MyReal { private Double d; private void InitFromString(string) {this.d = ...;} public MyReal(Double d) { this.d = d;} public MyReal(string val) { this.d = default(Double); InitFromString(val);} public override string ToString() { return this.real.ToString();} public static explicit operator MyReal(string s) { return new MyReal(s);} public static implicit operator String(MyReal r) { return r.ToString();} ... } OK, I use the MyTable as a binding source for a DataGridView. I can load the data grid easily using InitFromString on individual fields in MyStruct. The problem comes when I try to edit a value in a cell of the DataGridView. Going to the first row, first column, I change the value of the existing number. It gives an exception blizzard, the first line of which says: System.FormatException: Invalid cast from 'System.String' to 'MyReal' I've looked at the casting discussions and reference books but don't see any obvious problems. Any ideas?

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  • How to display total record count against models in django admin

    - by Rog
    Is there a neat way to make the record/object count for a model appear on the main model list in the admin module? I have found techniques for showing counts of related objects within sets in the list_display page (and I can see the total in the pagination section at the bottom of the same), but haven't come across a neat way to show the record count at the model list level.

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  • Replacing specific HTML tags using Regex

    - by matthewpe
    Alright, an easy one for you guys. We are using ActiveReport's RichTextBox to display some random bits of HTML code. The HTML tags supported by ActiveReport can be found here : http://www.datadynamics.com/Help/ARNET3/ar3conSupportedHtmlTagsInRichText.html An example of what I want to do is replace any match of <div style="text-align:*</div> by <p style=\"text-align:*</p> in order to use a supported tag for text-alignment. I have found the following regex expression to find the correct match in my html input: <div style=\"text-align:(.*?)</div> However, I can't find a way to keep the previous text contained in the tags after my replacement. Any clue? Is it me or Regex are generally a PITA? :) private static readonly IDictionary<string, string> _replaceMap = new Dictionary<string, string> { {"<div style=\"text-align:(.*?)</div>", "<p style=\"text-align:(.*?)</p>"} }; public static string FormatHtml(string html) { foreach(var pair in _replaceMap) { html = Regex.Replace(html, pair.Key, pair.Value); } return html; } Thanks!

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  • Producing Mini Dumps for _caught_ SEH exceptions in mixed code DLL

    - by Assaf Lavie
    I'm trying to use code similar to clrdump to create mini dumps in my managed process. This managed process invokes C++/CLI code which invokes some native C++ static lib code, wherein SEH exceptions may be thrown (e.g. the occasional access violation). C# WinForms -> C++/CLI DLL -> Static C++ Lib -> ACCESS VIOLATION Our policy is to produce mini dumps for all SEH exceptions (caught & uncaught) and then translate them to C++ exceptions to be handled by application code. This works for purely native processes just fine; but when the application is a C# application - not so much. The only way I see to produce dumps from SEH exceptions in a C# process is to not catch them - and then, as unhandled exceptions, use the Application.ThreadException handler to create a mini dump. The alternative is to let the CLR translate the SEH exception into a .Net exception and catch it (e.g. System.AccessViolationException) - but that would mean no dump is created, and information is lost (stack trace information in Exception isn't as rich as the mini dump). So how can I handle SEH exceptions by both creating a minidump and translating the exception into a .Net exception so that my application may try to recover?

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  • Apache rewrite rules redux

    - by AlexanderJohannesen
    I've got a REST framework that when plopped into any directory should Just Work(TM), and it seems to work fine when I've got projects in subdirectories, but not if it's in root. So, given a few example directories; / /project1 /bingo/project2 /hoopla/doopla/minor/project3 All of these works fine, except I'm getting "funnies"* when the project runs in the root directory (bit hard to explain, I suppose, but the second level rewrites are not working properly). Here's my attempt at a generic .htaccess file: RewriteEngine On RewriteRule ^static/ - [L] RewriteCond %{REQUEST_URI} ^$ RewriteRule .* ./ [R,L] RewriteRule ^index.php - [L] RewriteRule (.*) index.php?q=$1 [QSA,PT] (And yes, all projects have a subdirectory ./static which is ignored by rewrites) What I'm trying to achieve is a set of rewrite rules that work for most cases (which is, again, plonking the project in a directory the webserver serves). I'm not a rewrite rules wiz by a long shot, and any good advice and gotchas would be appreciated (and yes, I've gone through too many introductory articles. I need some serious juice.) More info on the funnies; my webserver has docroot in one spot (under /usr/share/apache2/default-site/), but a set of rules that says that /projects is pulled in from somewhere else that's not a subdirectory of docroot (/home/user/Projects/). When I go there, I get a list of /projects subdirectories, and if one of those subdirectories gets called (restmapp) with the proposed rewrite rules, I get ; The requested URL /home/user/Projects/restmapp/index.php was not found on this server.

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  • Can't operator == be applied to generic types in C#?

    - by Hosam Aly
    According to the documentation of the == operator in MSDN, For predefined value types, the equality operator (==) returns true if the values of its operands are equal, false otherwise. For reference types other than string, == returns true if its two operands refer to the same object. For the string type, == compares the values of the strings. User-defined value types can overload the == operator (see operator). So can user-defined reference types, although by default == behaves as described above for both predefined and user-defined reference types. So why does this code snippet fail to compile? void Compare<T>(T x, T y) { return x == y; } I get the error Operator '==' cannot be applied to operands of type 'T' and 'T'. I wonder why, since as far as I understand the == operator is predefined for all types? Edit: Thanks everybody. I didn't notice at first that the statement was about reference types only. I also thought that bit-by-bit comparison is provided for all value types, which I now know is not correct. But, in case I'm using a reference type, would the the == operator use the predefined reference comparison, or would it use the overloaded version of the operator if a type defined one? Edit 2: Through trial and error, we learned that the == operator will use the predefined reference comparison when using an unrestricted generic type. Actually, the compiler will use the best method it can find for the restricted type argument, but will look no further. For example, the code below will always print true, even when Test.test<B>(new B(), new B()) is called: class A { public static bool operator==(A x, A y) { return true; } } class B : A { public static bool operator==(B x, B y) { return false; } } class Test { void test<T>(T a, T b) where T : A { Console.WriteLine(a == b); } }

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  • How do I concatenate strings in Objective-C?

    - by Typeoneerror
    Are there any shortcuts to (stringByAppendingString:) string concatenation in Objective-C or shortcuts for working with NSString or other objects in general? e.g. I'd like to make this: NSString *myString = @"This"; NSString *test = [myString stringByAppendingString:@" is just a test"]; something more like this: string myString = "This"; string test = myString + " is just a test";

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