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• Problem understanding Inheritance

  - by dhruvbird

  I've been racking my brains over inheritance for a while now, but am still not completely able to get around it. For example, the other day I was thinking about relating an Infallible Human and a Fallible Human. Let's first define the two: Infallible Human: A human that can never make a mistake. It's do_task() method will never throw an exception Fallible Human: A human that will occasionally make a mistakes. It's do_task() method may occasionally throw a ErrorProcessingRequest Exception The question was: IS an infallible human A fallible human OR IS a fallible human AN infallible human? The very nice answer I received was in the form of a question (I love these since it gives me rules to answer future questions I may have). "Can you pass an infallible human where a fallible human is expected OR can you pass a fallible human where an infallible human is expected?" It seems apparent that you can pass an infallible human where a fallible human is expected, but not the other way around. I guess that answered my question. However, it still feels funny saying "An infallible human is a fallible human". Does anyone else feel queasy when they say it? It almost feels as if speaking out inheritance trees is like reading out statements from propositional calculus in plain English (the if/then implication connectives don't mean the same as that in spoken English). Does anyone else feel the same?

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• Is starting to use CDATA a breaking change?

  - by kicsit

  For interaction with a customer's application we use XML documents. That is, we send an XML over HTTP and receive a response XML document the same way. The customer specified two XML schemata that describe the format of both the request and reply. All was working fine, until one day the customer started to use CDATA sections in the response XML. We set up our parser unmindful of CDATA sections, so we failed to interpret them. My question is: Who made a mistake here? I tried to find an answer in the XML standards, but I'm still not sure. I think I cannot prescribe using or not using CDATA's in an XSD, is that right? If so, is it not enough to agree upon an XSD, but a separate agreement has to be made about CDATA sections? Or one is obliged to be prepared to parse CDATA and regular text as well? I'm interested in both your personal views and official statements too. Thank you!

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• Weird flex date issue

  - by CodeMonkey

  Flex is driving me CRAZY and I think it's some weird gotcha with how it handles leap years and none leap years. So here's my example. I have the below dateDiff method that finds the number of days or milliseconds between two dates. If I run the following three statements I get some weird issues. dateDiff("date", new Date(2010, 0,1), new Date(2010, 0, 31)); dateDiff("date", new Date(2010, 1,1), new Date(2010, 1, 28)); dateDiff("date", new Date(2010, 2,1), new Date(2010, 2, 31)); dateDiff("date", new Date(2010, 3,1), new Date(2010, 3, 30)); If you were to look at the date comparisons above you would expect to get 30, 27, 30, 29 as the number of days between the dates. There weird part is that I get 29 when comparing March 1 to March 31. Why is that? Is it something to do with February only having 28 days? If anyone has ANY input on this that would be greatly appreciated. public static function dateDiff( datePart:String, startDate:Date, endDate:Date ):Number { var _returnValue:Number = 0; switch (datePart) { case "milliseconds": _returnValue = endDate.time - startDate.time; break; case "date": // TODO: Need to figure out DST problem i.e. 23 hours at DST start, 25 at end. // Math.floor causes rounding down error with DST start at dayOfYear _returnValue = Math.floor(dateDiff("milliseconds", startDate, endDate)/(1000 * 60 * 60 * 24)); break; } return _returnValue; }

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• Mysql dropping inserts with triggers

  - by user2891127

  Using mysql 5.5. I have two tables. One has a whitelist of hashes. When I insert a new row into the other table, I want to first compare the hash in the insert statement to the whitelist. If it's in the whitelist, I don't want to do the insert (less data to plow through later). The inserts are generated from another program and are text files with sql statements. I've been playing with triggers, and almost have it working: BEGIN IF (select count(md5hash) from whitelist where md5hash=new.md5hash) 0 THEN SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Already Whitelisted'; END IF; END But there's a problem. The Signal throwing up the error stops the import. I want to skip that line, not stop the whole import. Some searching didn't find any way to silently skip the import. My next idea was to create a duplicate table definition, and redirect the insert to that dup table. But the old and new don't seem to apply to table names. Other then adding an ignore column to my table then doing a mass drop based on that column after the import, is there any way to achieve my goal?

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• showDialog in Activity not displaying dialog

  - by Mohit Deshpande

  Here is my code: public class TasksList extends ListActivity { ... private static final int COLUMNS_DIALOG = 7; private static final int ORDER_DIALOG = 8; ... /** * @see android.app.Activity#onCreateDialog(int) */ @Override protected Dialog onCreateDialog(int id) { Dialog dialog; final String[] columns; Cursor c = managedQuery(Tasks.CONTENT_URI, null, null, null, null); columns = c.getColumnNames(); final String[] order = { "Ascending", "Descending" }; switch (id) { case COLUMNS_DIALOG: AlertDialog.Builder columnDialog = new AlertDialog.Builder(this); columnDialog.setSingleChoiceItems(columns, -1, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { bundle.putString("column", columns[which]); } }); dialog = columnDialog.create(); case ORDER_DIALOG: AlertDialog.Builder orderDialog = new AlertDialog.Builder(this); orderDialog.setSingleChoiceItems(order, -1, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { String orderS; if (order[which].equalsIgnoreCase("Ascending")) orderS = "ASC"; else orderS = "DESC"; bundle.putString("order", orderS); } }); dialog = orderDialog.create(); default: dialog = null; } return dialog; } /** * @see android.app.Activity#onOptionsItemSelected(android.view.MenuItem) */ @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case SORT_MENU: showDialog(COLUMNS_DIALOG); showDialog(ORDER_DIALOG); String orderBy = bundle.getString("column") + bundle.getString("order"); Cursor tasks = managedQuery(Tasks.CONTENT_URI, projection, null, null, orderBy); adapter = new TasksAdapter(this, tasks); getListView().setAdapter(adapter); break; case FILTER_MENU: break; } return false; } The showDialog doesn't display the dialog. I used the Debugger and it does executes these statements, but the dialog doesn't show. }

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• Using enum values to represent binary operators (or functions)

  - by Bears will eat you

  I'm looking for an elegant way to use values in a Java enum to represent operations or functions. My guess is, since this is Java, there just isn't going to be a nice way to do it, but here goes anyway. My enum looks something like this: public enum Operator { LT, LTEQ, EQEQ, GT, GTEQ, NEQ; ... } where LT means < (less than), LTEQ means <= (less than or equal to), etc - you get the idea. Now I want to actually use these enum values to apply an operator. I know I could do this just using a whole bunch of if-statements, but that's the ugly, OO way, e.g.: int a = ..., b = ...; Operator foo = ...; // one of the enum values if (foo == Operator.LT) { return a < b; } else if (foo == Operator.LTEQ) { return a <= b; } else if ... // etc What I'd like to be able to do is cut out this structure and use some sort of first-class function or even polymorphism, but I'm not really sure how. Something like: int a = ..., b = ...; Operator foo = ...; return foo.apply(a, b); or even int a = ..., b = ...; Operator foo = ...; return a foo.convertToOperator() b; But as far as I've seen, I don't think it's possible to return an operator or function (at least, not without using some 3rd-party library). Any suggestions?

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• Using LINQ, need help splitting a byte array on data received from Silverlight sockets

  - by gcadmes

  The message packats received contains multiple messages deliniated by a header=0xFD and a footer=0xFE // sample message packet with three // different size messages List<byte> receiveBuffer = new List<byte>(); receiveBuffer.AddRange(new byte[] { 0xFD, 1, 2, 0xFE, 0xFD, 1, 2, 3, 4, 5, 6, 7, 8, 0xFE, 0xFD, 33, 65, 25, 44, 0xFE}); // note: this sample code is without synchronization, // statements, error handling...etc. while (receiveBuffer.Count > 0) { var bytesInRange = receiveBuffer.TakeWhile(n => n != 0xFE); foreach (var n in bytesInRange) Console.WriteLine(n); // process message.. // 1) remove bytes read from receive buffer // 2) construct message object... // 3) etc... receiveBuffer.RemoveRange(0, bytesInRange.Count()); } As you can see, (including header/footer) the first message in this message packet contains 4 bytes, and the 2nd message contains 10 bytes,a and the 3rd message contains 6 bytes. In the while loop, I was expecting the TakeWhile to add the bytes that did not equal the footer part of the message. Note: Since I am removing the bytes after reading them, the header can always be expected to be at position '0'. I searched examples for splitting byte arrays, but non demonstrated splitting on arrays of unknown and fluctuating sizes. Any help will be greatly appreciated. thanks much!

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• PHP cache header override

  - by Soyo

  I've been through over 100 answers here, lots to try, NOTHING working?? Have a PHP based site. I need caching OFF for all .php files EXCEPT A SELECT FEW. So, in .htaccess, I have the following: ExpiresActive On # Eliminate caching for certain dynamic files <FilesMatch "\.(php|cgi|pl)$"> ExpiresDefault A0 Header set Cache-Control "no-cache, no-store, must-revalidate, max-age=0, proxy-revalidate, no-transform" Header set Pragma "no-cache" </FilesMatch> Using Firebug, I see the following: Cache-Control no-cache, no-store, must-revalidate, max-age=0, proxy-revalidate, no-transform Connection Keep-Alive Content-Type text/html Date Sun, 02 Sep 2012 19:22:27 GMT Expires Sun, 02 Sep 2012 19:22:27 GMT Keep-Alive timeout=3, max=100 Pragma no-cache Server Apache Transfer-Encoding chunked X-Powered-By PHP/5.2.17 Hey, Looks great! BUT, I have a couple .php pages I need some very short caching on. I thought the simple answer was having this added to the very top of each php page in which I want caching enabled: <?php header("Cache-Control: max-age=360"); ?> Nope. Then I tried various versions of the above. Nope. Then I tried meta http-equiv variations. Nope. Then I tried variations of the .htaccess code along with the above variations, such as limiting it to: # Eliminate caching for certain dynamic files <FilesMatch "\.(php|cgi|pl)$"> Header set Cache-Control "no-cache, max-age=0" </FilesMatch> Nope. It seems nothing I do will allow a single .php to be cache enabled with the .htaccess code in place, short of removing the statements from the .htaccess file altogether. Where am I going wrong? What do I have to do to get individual php pages to be cacheable while the rest remain off?? Thank you for any thoughts.

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• Does BeginReceive() get everything sent by BeginSend()?

  - by IVlad

  I'm writing a program that will have both a server side and a client side, and the client side will connect to a server hosted by the same program (but by another instance of it, and usually on another machine). So basically, I have control over both aspects of the protocol. I am using BeginReceive() and BeginSend() on both sides to send and receive data. My question is if these two statements are true: Using a call to BeginReceive() will give me the entire data that was sent by a single call to BeginSend() on the other end when the callback function is called. Using a call to BeginSend() will send the entire data I pass it to the other end, and it will all be received by a single call to BeginReceive() on the other end. The two are basically the same in fact. If the answer is no, which I'm guessing is the case based on what I've read about sockets, what is the best way to handle commands? I'm writing a game that will have commands such as PUT X Y. I was thinking of appending a special character (# for example) to the end of each command, and each time I receive data, I append it to a buffer, then parse it only after I encounter a #.

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• How to account for non-prime numbers 0 and 1 in java?

  - by shady

  I'm not sure if this is the right place to be asking this, but I've been searching for a solution for this on my own for quite some time, so hopefully I've come to the right place. When calculating prime numbers, the starting number that each number has to be divisible by is 2 to be a non-prime number. In my java program, I want to include all the non-prime numbers in the range from 0 to a certain number, so how do I include 0 and 1? Should I just have separate if and else-if statements for 0 and 1 that state that they are not prime numbers? I think that maybe 0 and 1 should be included in the java for loop, but I don't know how to go about doing that. for (int i = 2; i < num; i++){ if (num % i == 0){ System.out.println(i + " is not a prime number. "); } else{ System.out.println(i + " is a prime number. "); } }

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• Win conditions for a connect-4 like game

  - by FrozenWasteland

  I have an 5x10 array that is populated with random values 1-5. I want to be able to check when 3 numbers, either horizontally, or vertically, match. I can't figure out a way to do this without writing a ton of if statements. Here is the code for the randomly populated array int i; int rowincrement = 10; int row = 0; int col = 5; int board[10][5]; int randomnum = 5; int main(int argc, char * argv[]) { srand(time(NULL)); cout << "============\n"; while(row < rowincrement) { for(i = 0; i < 5; i++) { board[row][col] = rand()%5 + 1; cout << board[row][col] << " "; } cout << endl; cout << "============\n"; row++; } cout << endl; return 0; }

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• Migrate from Oracle to MySQL

  - by Cassy

  Hi together. We ran into serious performance problems with our Oracle database and we would like to try to migrate to a MySQL-based database (either MySQL directly or, more preferrable, Infobright). The thing is, we need to let the old and the new system overlap for at least some weeks if not months, before we actually know, if all features of the new database match our needs. So, here is our situation: The Oracle database consists of multiple tables with each millions of rows. During the day, there are literally thousands of statements, which we cannot stop for migration. Every morning, new data is imported into the Oracle database, replacing some thousands of rows. Copying this process is not a problem, so we could, in theory, import in both databases in parallel. But, and here lies the challenge, for this to work, we need to have an export from the Oracle database with a consistent state from one day. (We cannot export some tables on Monday and some others on Tuesday, etc.) This means, that at least the export should be finished in less than one day. Our first thought was to dump the schema, but I wasn't able to find a tool to import an Oracle dump file into mysql. Exporting tables in CSV files might work, but I'm afraid it could take too long. So my question now is: What should I do? Is there any tool to import Oracle dump files into MySQL? Does anybody have any experience with such a large-scale migration? Thanks in advance, Cassy PS: Please, don't suggest performance optimization techniques for Oracle, we already tried a lot :-)

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• sprintf bug with php & apache in windows?

  - by potatoe

  I've run into a strange problem on a WAMP server setup (PHP version 5.3.0, Apache 2.2.11). When using sprintf to output a number, I occasionally get erroneous characters in the output string. Example: (not trimmed from anything, this is the only code in the script) $dt1 = new DateTime('now'); $dt2 = new DateTime('now - 10 min'); $interval = $dt1->diff($dt2); $number = 10.0; $string = sprintf("%.1f", $number); echo "number: $number, string: $string\n"; If I run this at the command prompt with PHP CLI, I get the expected output: number: 10, string: 10.0 However, if I serve it using Apache, in the browser I get number: 10, string: :.0 with a colon where '10' should be. (Note that ':' is the next ascii character in sequence after '9', if $number is 0-9, everything works. Numbers greater than 10 appear to use ascii equivalents - so 11 is ';', 12 is '<', etc.) The strangest part is that the first four lines in the above code sample seem to affect the results. Logically, those statements should have no impact, but if I comment them out or remove them the problem goes away. Any ideas? Anyone else able to replicate this?

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• Rails active record association problem

  - by Harm de Wit

  Hello, I'm new at active record association in rails so i don't know how to solve the following problem: I have a tables called 'meetings' and 'users'. I have correctly associated these two together by making a table 'participants' and set the following association statements: class Meeting < ActiveRecord::Base has_many :participants, :dependent => :destroy has_many :users, :through => :participants and class Participant < ActiveRecord::Base belongs_to :meeting belongs_to :user and the last model class User < ActiveRecord::Base has_many :participants, :dependent => :destroy At this point all is going well and i can access the user values of attending participants of a specific meeting by calling @meeting.users in the normal meetingshow.html.erb view. Now i want to make connections between these participants. Therefore i made a model called 'connections' and created the columns of 'meeting_id', 'user_id' and 'connected_user_id'. So these connections are kinda like friendships within a certain meeting. My question is: How can i set the model associations so i can easily control these connections? I would like to see a solution where i could use @meeting.users.each do |user| user.connections.each do |c| <do something> end end I tried this by changing the model of meetings to this: class Meeting < ActiveRecord::Base has_many :participants, :dependent => :destroy has_many :users, :through => :participants has_many :connections, :dependent => :destroy has_many :participating_user_connections, :through => :connections, :source => :user Please, does anyone have a solution/tip how to solve this the rails way?

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• Query table value aliasing in Oracle SQL

  - by Strata

  I have a homework assignment in SQL for Oracle 10g where I have to apply union to two different select statements, to return two columns. I need the values of each cell under vendor_state to indicate CA and every other value in another state to return "Outside CA", to indicate they're elsewhere. I applied the union and produced the two columns and the listings for CA, but many other state IDs were listed and I couldn't find an explanation for how to change the actual values in the query itself. Eventually, I stumbled on an answer, but I can't explain why this works. The code is as follows: SELECT vendor_name, vendor_state FROM vendors WHERE vendor_state IN 'CA' UNION SELECT vendor_name, 'Outside CA' AS vendor_state FROM vendors WHERE vendor_state NOT IN 'CA' ORDER BY vendor_name This gives me the exact answer I need, but I don't know why the aliasing in the second select statement can behave this way....no explanation is given in my textbook and nothing I've read indicates that column aliasing can be done like this. But, by switching the column name and the alias value, I have replaced the value being returned rather than the column name itself...I'm not complaining about the result, but it would help if I knew how I did it.

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• Sqlite3 INSERT INTO Question × 377

  - by user316717

  Hi, My 1st post. I am creating an exercise app that will record the weight used and the number of "reps" the user did in 4 "Sets" per day over a period of 7 days so the user may view their progress. I have built the database table named FIELDS with 2 columns ROW and FIELD_DATA and I can use the code below to load the data into the db. But the code has a sql statement that says, INSERT OR REPLACE INTO FIELDS (ROW, FIELD_DATA)VALUES (%d, '%@'); When I change the statment to: INSERT INTO FIELDS (ROW, FIELD_DATA)VALUES (%d, '%@'); Nothing happens. That is no data is recorded in the db. Below is the code: #define kFilname @"StData.sqlite3" - (NSString *)dataFilePath { NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; return [documentsDirectory stringByAppendingPathComponent:kFilname]; } -(IBAction)saveData:(id)sender; { for (int i = 1; i <= 8; i++) { NSString *fieldName = [[NSString alloc]initWithFormat:@"field%d", i]; UITextField *field = [self valueForKey:fieldName]; [fieldName release]; NSString *insert = [[NSString alloc] initWithFormat: @"INSERT OR REPLACE INTO FIELDS (ROW, FIELD_DATA) VALUES (%d, '%@');",i, field.text]; // sqlite3_stmt *stmt; char *errorMsg; if (sqlite3_exec (database, [insert UTF8String], NULL, NULL, &errorMsg) != SQLITE_OK) { // NSAssert1(0, @"Error updating table: %s", errorMsg); sqlite3_free(errorMsg); } } sqlite3_close(database); } So how do I modify the code to do what I want? It seemed like a simple sql statement change at first but obviously there must be more. I am new to Objective-C and iPhone programming. I am not new to using sql statements as I have been creating web apps in ASP for a number of years. Any help will be greatly appreciated, this is driving me nuts! Thanks in advance Dave

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• Obj-c method override/polymorphism problem

  - by Rod

  Ok, so I'm using Objective-C. Now, say I have: TopClass : NSObject - (int) getVal {return 1;} MidClass : TopClass - (int) getVal {return 2;} BotClass : MidClass - (int) getVal {return 3;} I then put objects of each type into an NSMutableArray and take one out. What I want to do is run the getVal func on the appropriate object type, but when I put id a = [allObjects objectAtIndex:0]; if ([a isKindOfClass:[TopClass class]]) { int i; i = [a getVal]; } I get firstly a warning about multiple methods called getVal (presumably because the compiler can't determine the actual object type until runtime). But more seriously I also get an error "void value not ignored as it should be" and it won't compile. If I don't try and use the return from [a getVal] then it compiles fine e.g. [a getval]; //obviously no good if I want to use the return value It will also work if I use isMemberOfClass statements to cast the object to a class before running the function e.g. if ([a isMemberOfClass:[BotClass]) i = [(BotClass*) a getVal]; But surely I shouldn't have to do this to get the functionality I require? Otherwise I'll have to put in a statement for every single subclass, and worse have to add a new line if I add a new sub class, which rather defeats the point of method overriding doesn't it? Surely there is a better way?

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• is "else if" faster than "switch() case" ?

  - by John

  Hello, I'm an ex Pascal guy,currently learning C#. My question is the following: Is the code below faster than making a switch? int a = 5; if (a == 1) { .... } else if(a == 2) { .... } else if(a == 3) { .... } else if(a == 4) { .... } else .... And the switch: int a = 5; switch(a) { case 1: ... break; case 2: ... break; case 3: ... break; case 4: ... break; default: ... break; } Which one is faster? I'm asking ,because my program has a similiar structure(many,many "else if" statements). Should I turn them into switches?

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• Is there a way to sync (two way) tables betwen a mysql server and a local MS Access?

  - by Kailen

  Help me figure out a solution to a (not so unique) problem. My research group has gps devices attached to migratory animals. Every once in a while, a research tech will be within range of an animal and will get the chance to download all the logged points. Each individual spits out a single dbf and new locations are just appended to the end (so the file is just cumulative). These data need to be shared among a research group. Everyone else (besides me) wants to use access, so they can make small edits and prefer that interface. They do not like using MySQL. The solution I came up with is: a) The person who downloads the file goes to a web page, enters animal ID into a form, chooses .dbf file and uploads to a mysql database on the server (I still have to write php code to read the dbf and write sql insert statements from it). b) Everyone syncs from their local access database to the server. (This is natively possible from access but very clunky). Is there a tool (preferably open source), that can compare a access table to mysql table and sync the two (both ways)? Alternatively, does anyone have a more elegant solution? The ultimate goal is to allow everyone to have access to the most current data on their computers using their preferred database app.

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• preg_match to find the current directory in a URL

  - by Ian

  I'm trying to detect the current section of a site that a user is viewing by checking for the final directory in the URL. I'm using a PHP and regex to do it and I think I'm close but unfortunately not quite there yet. Here's what I currently have: <?php $url = $_SERVER['REQUEST_URI_PATH'] = preg_replace('/\\?.*/', '', $_SERVER['REQUEST_URI']); $one = '/one/'; $two = '/three/'; $three = '/three/'; $four = '/four/'; $five = '/five/'; echo $url; if (substr($_SERVER['REQUEST_URI_PATH'], 0, strlen($one)) == $one) { // URI path starts with "/one/" echo "The section is one."; } elseif (substr($_SERVER['REQUEST_URI_PATH'], 0, strlen($two)) == $two) { // URI path starts with "/two/" echo "The section is two."; } elseif (substr($_SERVER['REQUEST_URI_PATH'], 0, strlen($three)) == $three) { // URI path starts with "/three/" echo "The section is three."; } elseif (substr($_SERVER['REQUEST_URI_PATH'], 0, strlen($four)) == $four) { // URI path starts with "/four/" echo "The section is four."; } elseif (substr($_SERVER['REQUEST_URI_PATH'], 0, strlen($five)) == $five) { // URI path starts with "/five/" echo "The section is five."; } ?> I've placed in the echo before the if statements just to get confirmation of the value of $url. This outputs /currentdirectory/file.php However the conditions themselves don't match anything and my individual echo for each section never displays. Also if there's a simpler way of doing it then I'm open to suggestions. Thanks

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• Questions about shifting from mysql to PDO

  - by Scarface

  Hey guys I have recently decided to switch all my current plain mysql queries performed with php mysql_query to PDO style queries to improve performance, portability and security. I just have some quick questions for any experts in this database interaction tool Will it prevent injection if all statements are prepared? (I noticed on php.net it wrote 'however, if other portions of the query are being built up with unescaped input, SQL injection is still possible' I was not exactly sure what this meant). Does this just mean that if all variables are run through a prepare function it is safe, and if some are directly inserted then it is not? Currently I have a connection at the top of my page and queries performed during the rest of the page. I took a look at PDO in more detail and noticed that there is a try and catch procedure for every query involving a connection and the closing of that connection. Is there a straightforward way to connecting and then reusing that connection without having to put everything in a try or constantly repeat the procedure by connecting, querying and closing? Can anyone briefly explain in layman's terms what purpose a set_exception_handler serves? I appreciate any advice from any more experienced individuals.

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• Dynamic function arguments in C++, possible?

  - by Jeshwanth Kumar N K

  I am little new to C++, I have one doubt in variable argument passing. As I mentioned in a sample code below ( This code won't work at all, just for others understanding of my question I framed it like this), I have two functions func with 1 parameter and 2 parameters(parameter overloading). I am calling the func from main, before that I am checking whether I needs to call 2 parameter or 1 parameter. Here is the problem, as I know I can call two fuctions in respective if elseif statements, but I am curious to know whether I can manage with only one function. (In below code I am passing string not int, as I mentioned before this is just for others understanding purpose. #include<iostream.h> #include <string> void func(int, int); void func(int); void main() { int a, b,in; cout << "Enter the 2 for 2 arg, 1 for 1 arg\n"; cin << in; if ( in == 2) { string pass = "a,b"; } elseif ( in == 1) { string pass = "a"; } else { return 0; } func(pass); cout<<"In main\n"<<endl; } void func(int iNum1) { cout<<"In func1 "<<iNum1<<endl; } void func(int iNum1, int iNum2) { cout<<"In func2 "<<iNum1<<" "<<iNum2<<endl; }

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• C++ Segmentation Fault when Iterating through a Vector

  - by user1790374

  I have a program that maintains an integer vector. I have three functions that add an integer, remove an integer and check whether an integer is already in the vector. The problem is with the last one. vector<int> children; void CtpTestingApplication::addChild(int child) { for (int i=0; i<children.size(); i++) { //already a child if (children[i]==child) return; } //child not yet recorded children.push_back(child); received.push_back(false); cout<<"added child "<<child; } void CtpTestingApplication::removeChild(int child) { Enter_Method("removeChild"); for (int i=0; i<children.size(); i++) { //already a child, remove it if (children[i]==child) { children.erase(children.begin()+i); received.erase(received.begin()+i); cout<<"removed child "<<child; } } //not recorded, no need to remove } bool CtpTestingApplication::isChild(int child) { Enter_Method("isChild"); vector<int>::iterator ic; bool result = false; for (ic= children.begin(); ic < children.end(); ic++) { cout<<*ic<<" vs "<<child; // if (child==*ic) result = true; } return result; } I always get segmentation fault when I uncomment "if (child==*ic)", even though printouts show that the vector is not empty and contains the expected integers. For example, with the if statements commented, I can see 1 vs 4, 2 vs 4, 4 vs 4, 12 vs 4 I also attempted looping using children[i] and so on, but to no avail. Any help would be appreciated. Thank you.

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• Calculating percent "x/y * 100" always results in 0?

  - by Patrick Beninga

  In my assignment i have to make a simple version of Craps, for some reason the percentage assignments always produce 0 even when both variables are non 0, here is the code. import java.util.Random; Header, note the variables public class Craps { private int die1, die2,myRoll ,myBet,point,myWins,myLosses; private double winPercent,lossPercent; private Random r = new Random(); Just rolls two dies and produces their some. public int roll(){ die1 = r.nextInt(6)+1; die2 = r.nextInt(6)+1; return(die1 + die2); } The Play method, this just loops through the game. public void play(){ myRoll = roll(); point = 0; if(myRoll == 2 ||myRoll == 3 || myRoll == 12){ System.out.println("You lose!"); myLosses++; }else if(myRoll == 7 || myRoll == 11){ System.out.println("You win!"); myWins++; }else{ point = myRoll; do { myRoll = roll(); }while(myRoll != 7 && myRoll != point); if(myRoll == point){ System.out.println("You win!"); myWins++; }else{ System.out.println("You lose!"); myLosses++; } } } This is where the bug is, this is the tester method. public void tester(int howMany){ int i = 0; while(i < howMany){ play(); i++; } bug is right here in these assignments statements winPercent = myWins/i * 100; lossPercent = myLosses/i* 100; System.out.println("program ran "+i+" times "+winPercent+"% wins "+ lossPercent+"% losses with "+myWins+" wins and "+myLosses+" losses"); } }

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• MS SQL: How to get the newest date in a table with several equal keys

  - by Qohelet

  Unfortunately my knowledge related to statements like "group by" and "having" is quite limited, so hopefully you can help me: I have a view -here's an excerpt- (if we have some Europeans here - it's v021 of Winline/Mesonic): ID | Artikelbezeichnung1 | Bez2 | mesoyear _____________________________________________________________________ 1401MA70 | Marga ,Saracena grigio,1S,33,3/33,3 | Marazzi | 1344 1401MA70 | Marga ,Saracena grigio,1S,33,3/33,3 | Marazzi | 1356 1401MA70 | Marga ,Saracena grigio,1S,33,3/33,3 | Marazzi | 1356 1401MA71 | Marga ,Saracena beige,1S,33,3/33,3 | Marazzi | 1344 1401MA71 | Marga ,Saracena beige,1S,33,3/33,3 | Marazzi | 1356 1401MA71 | Marga ,Saracena beige,1S,33,3/33,3 | Marazzi | 1356 2401CR13 | Crista,Mahon rojo,1S,33,3/33,3 | Cristacer | 1332 2401CR13 | Crista,Mahon rojo,1S,33,3/33,3 | Cristacer | 1344 So the ID is not unique and I just need the one with the highest val in "mesoyear". My fist solution was: Select c015 as ID, c003 as Artikelbezeichnung1, c074 as Bez2, mesoyear from CWLDATEN_91.dbo.v021 group by c015 having mesoyear = max(mesoyear) But this doesn't work at all... Msg 8121, Level 16, State 1, Line 8 Column 'CWLDATEN_91.dbo.v021.mesoyear' is invalid in the HAVING clause because it is not contained in either an aggregate function or the GROUP BY clause. So I just removed the "having" statement and it went "better": Msg 8120, Level 16, State 1, Line 2 Column 'CWLDATEN_91.dbo.v021.c003' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause. So I tried to remove the error just by adding things to the "group by". And it worked. Select c015 as ID, c003 as Artikelbezeichnung1, c074 as Bez2, max(mesoyear) from CWLDATEN_91.dbo.v021 group by c015,c003,c074 gives me exactly what I want. But the correct Select contains about 24 columns and some calculations as well. The problem can't be solved just by adding all the columns to the "group by"...? Can someone please help me to find a proper command? Thank you!

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