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  • F# operator over-loading question

    - by jyoung
    The following code fails in 'Evaluate' with: "This expression was expected to have type Complex but here has type double list" Am I breaking some rule on operator over-loading on '(+)'? Things are OK if I change '(+)' to 'Add'. open Microsoft.FSharp.Math /// real power series [kn; ...; k0] => kn*S^n + ... + k0*S^0 type Powers = double List let (+) (ls:Powers) (rs:Powers) = let rec AddReversed (ls:Powers) (rs:Powers) = match ( ls, rs ) with | ( l::ltail, r::rtail ) -> ( l + r ) :: AddReversed ltail rtail | ([], _) -> rs | (_, []) -> ls ( AddReversed ( ls |> List.rev ) ( rs |> List.rev) ) |> List.rev let Evaluate (ks:Powers) ( value:Complex ) = ks |> List.fold (fun (acc:Complex) (k:double)-> acc * value + Complex.Create(k, 0.0) ) Complex.Zero

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  • STL: how to overload operator= for <vector> ?

    - by MBes
    There's simple example: #include <vector> int main() { vector<int> veci; vector<double> vecd; for(int i = 0;i<10;++i){ veci.push_back(i); vecd.push_back(i); } vecd = veci; // <- THE PROBLEM } The thing I need to know is how to overload operator = so that I could make assignment like this: vector<double> = vector<int>; I've just tried a lot of ways, but always compiler has been returning errors... Is there any option to make this code work without changing it? I can write some additional lines, but can't edit or delete the existing ones. Ty.

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  • Specification Pattern and Boolean Operator Precedence

    - by Anders Nielsen
    In our project, we have implemented the Specification Pattern with boolean operators (see DDD p 274), like so: public abstract class Rule { public Rule and(Rule rule) { return new AndRule(this, rule); } public Rule or(Rule rule) { return new OrRule(this, rule); } public Rule not() { return new NotRule(this); } public abstract boolean isSatisfied(T obj); } class AndRule extends Rule { private Rule one; private Rule two; AndRule(Rule one, Rule two) { this.one = one; this.two = two; } public boolean isSatisfied(T obj) { return one.isSatisfied(obj) && two.isSatisfied(obj); } } class OrRule extends Rule { private Rule one; private Rule two; OrRule(Rule one, Rule two) { this.one = one; this.two = two; } public boolean isSatisfied(T obj) { return one.isSatisfied(obj) || two.isSatisfied(obj); } } class NotRule extends Rule { private Rule rule; NotRule(Rule obj) { this.rule = obj; } public boolean isSatisfied(T obj) { return !rule.isSatisfied(obj); } } Which permits a nice expressiveness of the rules using method-chaining, but it doesn't support the standard operator precedence rules of which can lead to subtle errors. The following rules are not equivalent: Rule<Car> isNiceCar = isRed.and(isConvertible).or(isFerrari); Rule<Car> isNiceCar2 = isFerrari.or(isRed).and(isConvertible); The rule isNiceCar2 is not satisfied if the car is not a convertible, which can be confusing since if they were booleans isRed && isConvertible || isFerrari would be equivalent to isFerrari || isRed && isConvertible I realize that they would be equivalent if we rewrote isNiceCar2 to be isFerrari.or(isRed.and(isConvertible)), but both are syntactically correct. The best solution we can come up with, is to outlaw the method-chaining, and use constructors instead: OR(isFerrari, AND(isConvertible, isRed)) Does anyone have a better suggestion?

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  • Java operator overloading

    - by nimcap
    Not using operators makes my code obscure. (aNumber / aNother) * count is better than aNumber.divideBy(aNother).times(count) After 6 months of not writing a single comment I had to write a comment to the simple operation above. Usually I refactor until I don't need comment. And this made me realize that it is easier to read and perceive math symbols and numbers than their written forms. For example TWENTY_THOUSAND_THIRTEEN.plus(FORTY_TWO.times(TWO_HUNDERED_SIXTY_ONE)) is more obscure than 20013 + 42*261 So do you know a way to get rid of obscurity while not using operator overloading in Java? Update: I did not think my exaggeration on comments would cause such trouble to me. I am admitting that I needed to write comment a couple of times in 6 months. But not more than 10 lines in total. Sorry for that. Update 2: Another example: budget.plus(bonusCoefficient.times(points)) is more obscure than budget + bonusCoefficient * points I have to stop and think on the first one, at first sight it looks like clutter of words, on the other hand, I get the meaning at first look for the second one, it is very clear and neat. I know this cannot be achieved in Java but I wanted to hear some ideas about my alternatives.

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  • Constructor or Assignment Operator

    - by ju
    Can you help me is there definition in C++ standard that describes which one will be called constructor or assignment operator in this case: #include <iostream> using namespace std; class CTest { public: CTest() : m_nTest(0) { cout << "Default constructor" << endl; } CTest(int a) : m_nTest(a) { cout << "Int constructor" << endl; } CTest(const CTest& obj) { m_nTest = obj.m_nTest; cout << "Copy constructor" << endl; } CTest& operatorint rhs) { m_nTest = rhs; cout << "Assignment" << endl; return *this; } protected: int m_nTest; }; int _tmain(int argc, _TCHAR* argv[]) { CTest b = 5; return 0; } Or is it just a matter of compiler optimization?

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  • Conditional operator in Mako using Pylons

    - by Antoine Leclair
    In PHP, I often use the conditional operator to add an attribute to an html element if it applies to the element in question. For example: <select name="blah"> <option value="1"<?= $blah == 1 ? ' selected="selected"' : '' ?>> One </option> <option value="2"<?= $blah == 2 ? ' selected="selected"' : '' ?>> Two </option> </select> I'm starting a project with Pylons using Mako for the templating. How can I achieve something similar? Right now, I see two possibilities that are not ideal. Solution 1: <select name="blah"> % if blah == 1: <option value="1" selected="selected">One</option> % else: <option value="1">One</option> % endif % if blah == 2: <option value="2" selected="selected">Two</option> % else: <option value="2">Two</option> % endif </select> Solution 2: <select name="blah"> <option value="1" % if blah == 1: selected="selected" % endif >One</option> <option value="2" % if blah == 2: selected="selected" % endif >Two</option> </select> In this particular case, the value is equal to the variable tested (value="1" = blah == 1), but I use the same pattern in other situations, like <?= isset($variable) ? ' value="$variable" : '' ?>. I am looking for a clean way to achieve this using Mako.

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  • Efficiency of manually written loops vs operator overloads (C++)

    - by Sagekilla
    Hi all, in the program I'm working on I have 3-element arrays, which I use as mathematical vectors for all intents and purposes. Through the course of writing my code, I was tempted to just roll my own Vector class with simple +, -, *, /, etc overloads so I can simplify statements like: for (int i = 0; i < 3; i++) r[i] = r1[i] - r2[i]; // becomes: r = r1 - r2; Which should be more or less identical in generated code. But when it comes to more complicated things, could this really impact my performance heavily? One example that I have in my code is this: Manually written version: for (int j = 0; j < 3; j++) { p.vel[j] = p.oldVel[j] + (p.oldAcc[j] + p.acc[j]) * dt2 + (p.oldJerk[j] - p.jerk[j]) * dt12; p.pos[j] = p.oldPos[j] + (p.oldVel[j] + p.vel[j]) * dt2 + (p.oldAcc[j] - p.acc[j]) * dt12; } Using a Vector class with operator overloads: p.vel = p.oldVel + (p.oldAcc + p.acc) * dt2 + (p.oldJerk - p.jerk) * dt12; p.pos = p.oldPos + (p.oldVel + p.vel) * dt2 + (p.oldAcc - p.acc) * dt12; I am compiling my code for maximum possible speed, as it's extremely important that this code runs quickly and calculates accurately. So will me relying on my Vector's for these sorts of things really affect me? For those curious, this is part of some numerical integration code which is not trivial to run in my program. Any insight would be appreciated, as would any idioms or tricks I'm unaware of.

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  • Pair equal operator overloading for inserting into set

    - by Petwoip
    I am trying to add a pair<int,int> to a set. If a pair shares the same two values as another in the set, it should not be inserted. Here's my non-working code: typedef std::pair<int, int> PairInt; template<> bool std::operator==(const PairInt& l, const PairInt& r) { return (l.first == r.first && l.second == r.second) || (l.first == r.second && l.second == r.first); } int main() { std::set<PairInt> intSet; intSet.insert(PairInt(1,3)); intSet.insert(PairInt(1,4)); intSet.insert(PairInt(1,4)); intSet.insert(PairInt(4,1)); } At the moment, the (4,1) pair gets added even though there is already a (1,4) pair. The final contents of the set are: (1 3) (1 4) (4 1) and I want it to be (1 3) (1 4) I've tried putting breakpoints in the overloaded method, but they never get reached. What have I done wrong?

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  • NULL value when using NSDateFormatter after setting NSDate property via XML parsing

    - by David A Gibson
    Hello, I am using the following code to try and display in a time in a table cell. TimeSlot *timeSlot = [timeSlots objectAtIndex:indexPath.row]; NSDateFormatter *timeFormat = [[NSDateFormatter alloc] init]; [timeFormat setDateFormat:@"HH:mm:ss"]; NSLog(@"Time: %@", timeSlot.time); NSDate *mydate = timeSlot.time; NSLog(@"Time: %@", mydate); NSString *theTime = [timeFormat stringFromDate:mydate]; NSLog(@"Time: %@", theTime); The log output is this: 2010-04-14 10:23:54.626 MyApp[1080:207] Time: 2010-04-14T10:23:54 2010-04-14 10:23:54.627 MyApp[1080:207] Time: 2010-04-14T10:23:54 2010-04-14 10:23:54.627 MyApp[1080:207] Time: (null) I am new to developing for the iPhone and as it all compiles with no errors or warnings I am at a loss as to why I am getting NULL in the log. Is there anything wrong with this code? Thanks Further Info I used the code exactly from your answer lugte098 just to check and I was getting dates which leads me to believe that my TimeSlot class can't have a date correctly set in it's NSDate property. So my question becomes - how from XML do I set a NSDate property? I have this code (abbreviated): -(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *) string { if ([currentElement isEqualToString:@"Time"]) { currentTimeSlot.time = string } } Thanks

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  • Null Reference Exception In LINQ DataContext

    - by Frank
    I have a Null Reference Exception Caused by this code: var recentOrderers = (from p in db.CMS where p.ODR_DATE > DateTime.Today - new TimeSpan(60, 0, 0, 0) select p.SOLDNUM).Distinct(); result = (from p in db.CMS where p.ORDER_ST2 == "SH" && p.ODR_DATE > DateTime.Today - new TimeSpan(365, 0, 0, 0) && p.ODR_DATE < DateTime.Today - new TimeSpan(60, 0, 0, 0) && !(recentOrderers.Contains(p.SOLDNUM))/**/ select p.SOLDNUM).Distinct().Count(); result is of double type. When I comment out: !(recentOrderers.Contains(p.SOLDNUM)) The code runs fine. I have verified that recentOrderers is not null, and when I run: if(recentOrderes.Contains(0)) return; Execution follows this path and returns. Not sure what is going on, since I use similar code above it: var m = (from p in db.CMS where p.ORDER_ST2 == "SH" select p.SOLDNUM).Distinct(); double result = (from p in db.CUST join r in db.DEMGRAPH on p.CUSTNUM equals r.CUSTNUM where p.CTYPE3 == "cmh" && !(m.Contains(p.CUSTNUM)) && r.ColNEWMEMBERDAT.Value.Year > 1900 select p.CUSTNUM).Distinct().Count(); which also runs flawlessly. After noting the similarity, can anyone help? Thanks in advance. -Frank GTP, Inc.

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  • MySQL - NULL value check and Dynamic SQL inside stored procedure

    - by Mithun P
    DROP PROCEDURE IF EXISTS HaveSomeFun; CREATE PROCEDURE HaveSomeFun(user_id CHAR(50),house_id CHAR(50),room_id CHAR(50),fun_text TEXT,video_url CHAR(100)) BEGIN DECLARE query_full TEXT; SET @fields_part = 'INSERT INTO fun(FunKey,UserKey,FunBody,LastModified'; SET @values_part = CONCAT(') VALUES( NewBinKey(), KeyToBin(\"', user_id, '\"), \"', fun_text, '\", NOW() '); IF (house_id) THEN SET @fields_part = CONCAT(@fields_part, ', HouseKey'); SET @values_part = CONCAT(@values_part, ', KeyToBin(\'', house_id, '\')'); END IF; IF (room_id) THEN SET @fields_part = CONCAT(@fields_part, ', RoomKey'); SET @values_part = CONCAT(@values_part, ', KeyToBin(\'', room_id, '\')'); END IF; IF (video_url IS NOT NULL) THEN SET @fields_part = CONCAT(@fields_part, ', VideoURL'); SET @values_part = CONCAT(@values_part, ', "', video_url, '"'); END IF; SET query_full = CONCAT(@fields_part, @values_part, ' );'); SET @query_full = query_full; PREPARE STMT FROM @query_full; EXECUTE STMT; SELECT query_full; END; And CALL HaveSomeFun('29B455DE-A9BC-102D-9C16-00163EEDFCFC', '', 'F82C47A8-64DE-11DF-9D7E-0026B9481364', 'Jokes apart', ''); will construct the below string in the variable query_full INSERT INTO fun(FunKey,UserKey,FunBody,LastModified, VideoURL) VALUES( NewBinKey(), KeyToBin("29B455DE-A9BC-102D-9C16-00163EEDFCFC"), "Jokes apart", NOW() , "" ); But I need to get INSERT INTO fun(FunKey,UserKey,FunBody,LastModified, RoomKey, VideoURL) VALUES( NewBinKey(), KeyToBin("29B455DE-A9BC-102D-9C16-00163EEDFCFC"), "Jokes apart", NOW() , KeyToBin('F82C47A8-64DE-11DF-9D7E-0026B9481364'), "" ); Something is missing in the check IF (room_id) THEN. But I cannot impose IF (room_id IS NOT NULL) THEN since it will create KeyToBin('') and RoomKey is foreign key , KeyToBin('') will produce an invalid RoomKey. Any Idea?

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  • Use a non-coalescing parser in Axis2

    - by Nathan
    Does anyone know how I can get Axis2 to use a non-coalescing XMLStreamReader when it parses a SOAP message? I am writing code that reads a large base64 binary text element. Coalescing is the default behaviour, and this causes the default XMLStreamReader to load the entire text into memory rather than returning multiple CHARACTERS events. The upshot of this is that I run out of heap space when running the following code: reader = element.getTextAsStream( true ); The OutOfMemory error occurs in com.sun.org.apache.xerces.internal.impl.XMLStreamReaderImpl.next: java.lang.OutOfMemoryError: Java heap space at com.sun.org.apache.xerces.internal.util.XMLStringBuffer.append(XMLStringBuffer.java:208) at com.sun.org.apache.xerces.internal.util.XMLStringBuffer.append(XMLStringBuffer.java:226) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanContent(XMLDocumentFragmentScannerImpl.java:1552) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2864) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:607) at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:116) at com.sun.org.apache.xerces.internal.impl.XMLStreamReaderImpl.next(XMLStreamReaderImpl.java:558) at org.apache.axiom.util.stax.wrapper.XMLStreamReaderWrapper.next(XMLStreamReaderWrapper.java:225) at org.apache.axiom.util.stax.dialect.DisallowDoctypeDeclStreamReaderWrapper.next(DisallowDoctypeDeclStreamReaderWrapper.java:34) at org.apache.axiom.util.stax.wrapper.XMLStreamReaderWrapper.next(XMLStreamReaderWrapper.java:225) at org.apache.axiom.util.stax.dialect.SJSXPStreamReaderWrapper.next(SJSXPStreamReaderWrapper.java:138) at org.apache.axiom.om.impl.builder.StAXOMBuilder.parserNext(StAXOMBuilder.java:668) at org.apache.axiom.om.impl.builder.StAXOMBuilder.next(StAXOMBuilder.java:214) at org.apache.axiom.om.impl.llom.SwitchingWrapper.updateNextNode(SwitchingWrapper.java:1098) at org.apache.axiom.om.impl.llom.SwitchingWrapper.<init>(SwitchingWrapper.java:198) at org.apache.axiom.om.impl.llom.OMStAXWrapper.<init>(OMStAXWrapper.java:73) at org.apache.axiom.om.impl.llom.OMContainerHelper.getXMLStreamReader(OMContainerHelper.java:67) at org.apache.axiom.om.impl.llom.OMContainerHelper.getXMLStreamReader(OMContainerHelper.java:40) at org.apache.axiom.om.impl.llom.OMElementImpl.getXMLStreamReader(OMElementImpl.java:790) at org.apache.axiom.om.impl.llom.OMElementImplUtil.getTextAsStream(OMElementImplUtil.java:114) at org.apache.axiom.om.impl.llom.OMElementImpl.getTextAsStream(OMElementImpl.java:826) at org.example.UploadFileParser.invokeBusinessLogic(UploadFileParser.java:160)

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  • The maximum row size for the used table type, not counting BLOBs, is 65535. You have to change some columns to TEXT or BLOBs

    - by Matthew Chambers
    Hello I am getting the below message on a table i am trying to create The maximum row size for the used table type, not counting BLOBs, is 65535. You have to change some columns to TEXT or BLOBs Anyone know the answer to this please -- Table warrington_central.job -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS warrington_central.job ( id MEDIUMINT(8) UNSIGNED NOT NULL AUTO_INCREMENT , alias_title VARCHAR(255) NOT NULL , reference_number VARCHAR(100) NOT NULL , title VARCHAR(255) NOT NULL , primary_category SMALLINT(5) UNSIGNED NOT NULL , secondary_category SMALLINT(5) UNSIGNED NOT NULL , tertiary_category SMALLINT(5) UNSIGNED NULL , address_id BIGINT(20) UNSIGNED NOT NULL , geolocation_id BIGINT(20) UNSIGNED NULL , company VARCHAR(255) NOT NULL , description VARCHAR(10000) NOT NULL , skills_required VARCHAR(10000) NOT NULL , job_type TINYINT(2) UNSIGNED NOT NULL , experience_months_required TINYINT(2) UNSIGNED NOT NULL , experience_years_required TINYINT(2) UNSIGNED NOT NULL , salary_range VARCHAR(30) NOT NULL , extra_benefits_above_salary VARCHAR(500) NOT NULL , available_from DATE NULL , available_to DATE NULL , extra_location_details VARCHAR(1000) NOT NULL , contact_email VARCHAR(100) NOT NULL , contact_phone_number VARCHAR(20) NOT NULL , contact_mobile_number VARCHAR(20) NOT NULL , terms_conditions_application VARCHAR(5000) NOT NULL , link_to_profile ENUM('0','1') NOT NULL , created_on DATETIME NOT NULL , updated_on DATETIME NOT NULL , updated_by BIGINT(20) UNSIGNED NOT NULL , add_contact_form ENUM('0','1') NOT NULL , admin_package_id TINYINT(1) UNSIGNED NOT NULL , package_start_date DATETIME NOT NULL , package_end_date DATETIME NULL , package_comment VARCHAR(500) NOT NULL , viewable_to_members_only ENUM('0','1') NOT NULL , advertise_to DATETIME NULL , show_comment ENUM('0','1') NOT NULL , hits BIGINT(20) UNSIGNED NOT NULL DEFAULT 0 , visible ENUM('0','1') NOT NULL DEFAULT '0' , approved ENUM('I/* large SQL query (3.9 KB), snipped at 2,000 characters / / SQL Error (1118): Row size too large. The maximum row size for the used table type, not counting BLOBs, is 65535. You have to change some columns to TEXT or BLOBs */ SHOW WARNINGS;

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  • Cannot pass null to server using jQuery AJAX. Value received at the server is the string "null".

    - by Tom
    I am converting a javascript/php/ajax application to use jQuery to ensure compatibility with browsers other than Firefox. I am having trouble passing true, false, and null values using jQuery's ajax function. Javascript code: $.ajax ( { url : <server_url>, dataType: 'json', type : 'POST', success : receiveAjaxMessage, data: { valueTrue : true, valueFalse : false, valueNull : null } } ); PHP code: var_dump($_POST); Server output: array(3) { ["valueTrue"]=> string(4) "true" ["valueFalse"]=> string(5) "false" ["valueNull"]=> string(4) "null" } The problem is that the null, true, and false values are being converted to strings. The Javascript AJAX code currently in use passes null, true, and false correctly but only works in Firefox. Does anyone know how to solve this problem using jQuery? Here is some working code (not using jQuery) to compare with the code not-working code given above. Javascript Code: ajaxPort.send ( <server_url>, { valueTrue : true, valueFalse : false, valueNull : null } ); PHP code: var_dump(json_decode(file_get_contents('php://input'), true)); Server output: array(3) { ["valueTrue"]=> bool(true) ["valueFalse"]=> bool(false) ["valueNull"]=> NULL } Note that the null, true, and false values are correctly received. Note also that in the second method the $_POST array is not used in the PHP code. I think this is the key to the problem, but I cannot find a way to replicate this behavior using jQuery.

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  • "Invalid use of Null" when using Str() with a Null Recordset field, but Str(Null) works fine

    - by Mike Spross
    I'm banging my head against the wall on this one. I was looking at some old database reporting code written in VB6 and case across this line (the code is moving data from a "source" database into a reporting database): rsTarget!VehYear = Trim(Str(rsSource!VehYear)) When rsSource!VehYear is Null, the above line generates an "Invalid use of Null" run-time error. If I break on the above line and type the following in the Immediate pane: ?rsSource!VehYear It outputs Null. Fine, that makes sense. Next, I try to reproduce the error: ?Str(rsSource!VehYear) I get an "Invalid use of Null" error. However, if I type the following into the Immediate window: ?Str(Null) I don't get an error. It simply outputs Null. If I repeat the same experiment with Trim() instead of Str(), everything works fine. ?Trim(rsSource!VehYear) returns Null, as does ?Trim(Null). No run-time errors. So, my question is, how can Str(rsSource!VehYear) possibly throw an "Invalid use of Null" error when Str(Null) does not, when I know that rsSource!VehYear is equal to Null?

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  • $_FILES is null, $_POST is not null

    - by Cory Dee
    When I am going to upload a file, my $_POST variable knows the file name, but the $_FILES variable is null. I've used this code before, so I'm really stumped. Here's what I'm using for input: <label for="importFile">Attach Resume:</label> <input type="hidden" name="MAX_FILE_SIZE" value="10000000"> <input type="file" name="importFile" id="importFile" class="validate['required']"> And for processing: $uploaddir = "E:/Sites/OPL/2008/assets/apps/newjobs/resumes/"; $uploadfile = $uploaddir . time() . '-' . urlencode(basename($_FILES['importFile']['name'])); if (!move_uploaded_file($_FILES['importFile']['tmp_name'], $uploadfile)) { echo 'Error uploading file. Error number: ' . $_FILES['importFile']['error']; var_dump($_FILES['importFile']); echo $_POST['importFile']; die(); } Which is giving me this result: Error uploading file. Error number: NULL Maintaining The OPL Website.doc Any help would be greatly appreciated.

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  • Casting an object which could be null

    - by DeeMac
    DateTime? testDate = (DateTime?)arrayOfObjects[dateObject]; Does that code look ok? I attempted to use the as operator but I got the 'non-nullable' error. What I'm trying to say is that the object I'm choosing from the array is either DateTime or a null DateTime but either can be assigned to testDate. Doesn't feel right doing it this way, I think I'm missing something obvious. EDIT: I suppose it's the same as the way I could've adapted the as in the following way: DateTime? testDate = arrayOfObjects[dateObject] as DateTime?; Is either line of code the best way of handling potential nulls?

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  • MySQL "ERROR 1005 (HY000): Can't create table 'foo.#sql-12c_4' (errno: 150)"

    - by Ankur Banerjee
    Hi, I was working on creating some tables in database foo, but every time I end up with errno 150 regarding the foreign key. Firstly, here's my code for creating tables: CREATE TABLE Clients ( client_id CHAR(10) NOT NULL , client_name CHAR(50) NOT NULL , provisional_license_num CHAR(50) NOT NULL , client_address CHAR(50) NULL , client_city CHAR(50) NULL , client_county CHAR(50) NULL , client_zip CHAR(10) NULL , client_phone INT NULL , client_email CHAR(255) NULL , client_dob DATETIME NULL , test_attempts INT NULL ); CREATE TABLE Applications ( application_id CHAR(10) NOT NULL , office_id INT NOT NULL , client_id CHAR(10) NOT NULL , instructor_id CHAR(10) NOT NULL , car_id CHAR(10) NOT NULL , application_date DATETIME NULL ); CREATE TABLE Instructors ( instructor_id CHAR(10) NOT NULL , office_id INT NOT NULL , instructor_name CHAR(50) NOT NULL , instructor_address CHAR(50) NULL , instructor_city CHAR(50) NULL , instructor_county CHAR(50) NULL , instructor_zip CHAR(10) NULL , instructor_phone INT NULL , instructor_email CHAR(255) NULL , instructor_dob DATETIME NULL , lessons_given INT NULL ); CREATE TABLE Cars ( car_id CHAR(10) NOT NULL , office_id INT NOT NULL , engine_serial_num CHAR(10) NULL , registration_num CHAR(10) NULL , car_make CHAR(50) NULL , car_model CHAR(50) NULL ); CREATE TABLE Offices ( office_id INT NOT NULL , office_address CHAR(50) NULL , office_city CHAR(50) NULL , office_County CHAR(50) NULL , office_zip CHAR(10) NULL , office_phone INT NULL , office_email CHAR(255) NULL ); CREATE TABLE Lessons ( lesson_num INT NOT NULL , client_id CHAR(10) NOT NULL , date DATETIME NOT NULL , time DATETIME NOT NULL , milegage_used DECIMAL(5, 2) NULL , progress CHAR(50) NULL ); CREATE TABLE DrivingTests ( test_num INT NOT NULL , client_id CHAR(10) NOT NULL , test_date DATETIME NOT NULL , seat_num INT NOT NULL , score INT NULL , test_notes CHAR(255) NULL ); ALTER TABLE Clients ADD PRIMARY KEY (client_id); ALTER TABLE Applications ADD PRIMARY KEY (application_id); ALTER TABLE Instructors ADD PRIMARY KEY (instructor_id); ALTER TABLE Offices ADD PRIMARY KEY (office_id); ALTER TABLE Lessons ADD PRIMARY KEY (lesson_num); ALTER TABLE DrivingTests ADD PRIMARY KEY (test_num); ALTER TABLE Applications ADD CONSTRAINT FK_Applications_Offices FOREIGN KEY (office_id) REFERENCES Offices (office_id); ALTER TABLE Applications ADD CONSTRAINT FK_Applications_Clients FOREIGN KEY (client_id) REFERENCES Clients (client_id); ALTER TABLE Applications ADD CONSTRAINT FK_Applications_Instructors FOREIGN KEY (instructor_id) REFERENCES Instructors (instructor_id); ALTER TABLE Applications ADD CONSTRAINT FK_Applications_Cars FOREIGN KEY (car_id) REFERENCES Cars (car_id); ALTER TABLE Lessons ADD CONSTRAINT FK_Lessons_Clients FOREIGN KEY (client_id) REFERENCES Clients (client_id); ALTER TABLE Cars ADD CONSTRAINT FK_Cars_Offices FOREIGN KEY (office_id) REFERENCES Offices (office_id); ALTER TABLE Clients ADD CONSTRAINT FK_DrivingTests_Clients FOREIGN KEY (client_id) REFERENCES Clients (client_id); These are the errors that I get: mysql> ALTER TABLE Applications ADD CONSTRAINT FK_Applications_Cars FOREIGN KEY (car_id) REFERENCES Cars (car_id); ERROR 1005 (HY000): Can't create table 'foo.#sql-12c_4' (errno: 150) I ran SHOW ENGINE INNODB STATUS which gives a more detailed error description: ------------------------ LATEST FOREIGN KEY ERROR ------------------------ 100509 20:59:49 Error in foreign key constraint of table practice9/#sql-12c_4: FOREIGN KEY (car_id) REFERENCES Cars (car_id): Cannot find an index in the referenced table where the referenced columns appear as the first columns, or column types in the table and the referenced table do not match for constraint. Note that the internal storage type of ENUM and SET changed in tables created with >= InnoDB-4.1.12, and such columns in old tables cannot be referenced by such columns in new tables. See http://dev.mysql.com/doc/refman/5.1/en/innodb-foreign-key-constraints.html for correct foreign key definition. ------------ I searched around on StackOverflow and elsewhere online - came across a helpful blog post here with pointers on how to resolve this error - but I can't figure out what's going wrong. Any help would be appreciated!

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  • C++ OOP - Can you 'overload a cast' <- hard to explain in 1 sentence

    - by Brandon Miller
    Well, the WinAPI has a POINT struct, but I am trying to make an alternative class to this so you can set the values of x and y from a constructor. /** * X-Y coordinates */ class Point { public: int X, Y; Point(void) : X(0), Y(0) {} Point(int x, int y) : X(x), Y(y) {} Point(const POINT& pt) : X(pt.x), Y(pt.y) {} Point& operator= (const POINT& other) { X = other.x; Y = other.y; } }; // I have an assignment operator and copy constructor. Point myPtA(3,7); Point myPtB(8,5); POINT pt; pt.x = 9; pt.y = 2; // I can assign a 'POINT' to a 'Point' myPtA = pt; // But I also want to be able to assign a 'Point' to a 'POINT' pt = myPtB; Is it possible to overload operator= in a way so that I can assign a Point to a POINT? Or maybe some other method to achieve this? Thanks in advance.

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  • ASX: Just Another Stock Market Operator

    - by Theresa Hickman
    I try to stay informed with what's happening in global financial markets since we all know they are all interconnected. Last week, on Mar. 11 2010, Australia's Senate passed a law that reduced Australia's stock market's role to just a stock market operator. Before this, ASX (Australian Stock Exchange) acted as both its own regulator and operator (supervising trade actvities and handling the trades) of Australia's stock market. Many viewed this as a conflict of interest. So now, the Australian Securities & Investments Commision (ASIC) will act as regulator and ASX will simply be a stock market operator to ensure the continued integrity of financial markets. I believe what this is doing is laying the groundwork to have more than one stock exchange in Australia. I woudn't be surpised if Nasdaq makes a play. As you may or may not know, Nasdaq had been trying for years to take over control of the London Stock Exchange (LSE), which LSE had rejected because it thinks it is worth more than what Nasdaq is willing to pay. Nasdaq or even NYSE may want a piece of Asia/Pacific because nowadays most of the IPOs are coming from foreign companies outside the US. I didn't know this, but apparently many Asia/Pacific stock exchanges have a monopoly where they act as both regulator and operator. I'll be curious to see what happens after the ASIC meet and decide how to regulate Australia's stock exchange to see how many suitors come running towards Australia's financial market.

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  • JQuery getJSON Callback Returning Null Data

    - by user338828
    I have a getJSON call that is called back correctly, but the data variable is null. The python code posted below is executed by the getJSON call to the demandURL. Any ideas? javascript: var demandURL = "/demand/washington/"; $.getJSON(demandURL, function(data) { console.log(data); }); python: data = {"demand_count":"one"} json = simplejson.dumps(data) return HttpResponse(json, mimetype="application/json")

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  • null value exception thrown when deserializing null value JSON.net

    - by Bharath
    Hi Friends I am trying to deserialize a hidden control field into a json object the code is as follows Dim settings As New Newtonsoft.Json.JsonSerializerSettings() settings.NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore Return Newtonsoft.Json.JsonConvert.DeserializeObject(Of testContract)(txtHidden.Text, settings) But I am getting the following exception. value cannot be null parameter name s: I even added the following lines but it still does not work out. Please help settings.MissingMemberHandling = Newtonsoft.Json.MissingMemberHandling.Ignore settings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore settings.ObjectCreationHandling = Newtonsoft.Json.ObjectCreationHandling.Replace Thanks Bharath

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  • GetHashCode on null fields?

    - by Shimmy
    How do I deal with null fields in GetHashCode function? Module Module1 Sub Main() Dim c As New Contact Dim hash = c.GetHashCode End Sub Public Class Contact : Implements IEquatable(Of Contact) Public Name As String Public Address As String Public Overloads Function Equals(ByVal other As Contact) As Boolean _ Implements System.IEquatable(Of Contact).Equals Return Name = other.Name AndAlso Address = other.Address End Function Public Overrides Function Equals(ByVal obj As Object) As Boolean If ReferenceEquals(Me, obj) Then Return True If TypeOf obj Is Contact Then Return Equals(DirectCast(obj, Contact)) Else Return False End If End Function Public Overrides Function GetHashCode() As Integer Return Name.GetHashCode Xor Address.GetHashCode End Function End Class End Module

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  • DPAPI encryted section returns null

    - by Jay
    Hi, I am encrypting the appSettings and the connectionStrings sections in the app.config file. But when I try to read the value, its always returning null. I am not sure if I am missing something. I thought the decryption was transparent. Has anyone else had any success with reading DPAPI protected sections in the app.config file.

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