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• Altering an embedded truetype font so it will be useable by Windows GDI

  - by Ritsaert Hornstra

  I am trying to render PDF content to a GDI device context (a 24bit bitmap to be exact). Parsing the PDF stream into PDF objects and rendering the PDF commands from the content dictionary works well, inclduing font rendering. Embedded fonts are decompressed from their FontFile streams and "loaded" using AddFontMemResourceEx. Now some embedded fonts remove some TrueType tables that are needed by GDI, like the NAME table. Because of this, I tried to modify the font by parsing the TrueType subset font into it's tables and modify those tables that have data missing / missing tables are regenerated with as correct information as possible. I use the Microsoft Font Validator tool to see how "correct" the generated font is. I still get a few errors, like for the maxp table the max values are usually too large (it is a subset) or The xAvgCharWidth field does not equal the calculated value of the OS/2 table is not correct but this does not stop other embedded fonts to be useable.The fonts embedded using PDFCreator are the ones that are problematic. Question: - How can I determine what I need to change to the font file in order for GDI to be able to use it? - Are there any other font validation tools that might give me insight into what is still wrong with the fontfile? If needed: I can make an original fontfile and an altered fontfile available for download somewhere.

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• What's the best way to resolve this scope problem?

  - by Peter Stewart

  I'm writing a program in python that uses genetic techniques to optimize expressions. Constructing and evaluating the expression tree is the time consumer as it can happen billions of times per run. So I thought I'd learn enough c++ to write it and then incorporate it in python using cython or ctypes. I've done some searching on stackoverflow and learned a lot. This code compiles, but leaves the pointers dangling. I tried 'this_node = new Node(...' . It didn't seem to work. And I'm not at all sure how I'd delete all the references as there would be hundreds. I'd like to use variables that stay in scope, but maybe that's not the c++ way. What is the c++ way? class Node { public: char *cargo; int depth; Node *left; Node *right; } Node make_tree(int depth) { depth--; if(depth <= 0) { Node tthis_node("value",depth,NULL,NULL); return tthis_node; } else { Node this_node("operator" depth, &make_tree(depth), &make_tree(depth)); return this_node; } };

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• C++ Beginner Delete Question

  - by Pooch

  Hi all, This is my first year learning C++ so bear with me. I am attempting to dynamically allocate memory to the heap and then delete the allocated memory. Below is the code that is giving me a hard time: // String.cpp #include "String.h" String::String() {} String::String(char* source) { this->Size = this->GetSize(source); this->CharArray = new char[this->Size + 1]; int i = 0; for (; i < this->Size; i++) this->CharArray[i] = source[i]; this->CharArray[i] = '\0'; } int String::GetSize(const char * source) { int i = 0; for (; source[i] != '\0'; i++); return i; } String::~String() { delete[] this->CharArray; } Here is the error I get when the compiler tries to delete the CharArray: 0xC0000005: Access violation reading location 0xccccccc0. And here is the last call on the stack: msvcr100d.dll!operator delete(void * pUserData) Line 52 + 0x3 bytes C++ I am fairly certain the error exists within this piece of code but will provide you with any other information needed. Oh yeah, using VS 2010 for XP. Thanks for any and all help!

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• Good strategy for copying a "sliding window" of data from a table?

  - by chiborg

  I have a MySQL table from a third-party application that has millions of rows and only one index - the timestamp of each entry. Now I want to do some heavy self-joins and queries on the data using fields other than the timestamp. Doing the query on the original table would bring the database to a crawl, adding indexes to the table is not an option. Additionally, I only need entries that are newer than one week. My current strategy for doing the queries efficiently is to use a separate table (aux_table) that has the necessary indexes. My questions are: Is there another way to do the queries? and if not, How do I update the data in the indexed table efficiently? So far I have found two approaches for updating aux_table: Truncate aux_table and insert the desired data from the original table. Not very efficient because all the indexes must be re-crated. Check for the biggest timestamp in aux_table and insert all entries with a greater or equal timestamp from the original table. Occasionally drop older entries. Only copying entries with greater timestamp leads to dropped entries (because of entries with same timestamp that were inserted into the original table after the last update).

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• Work for huge company or small company that makes products for huge company?

  - by TheGambler

  I'm facing a career decision. I currently work for a huge, huge, huge company (this should bring 3-4 companies to mind) as a programmer. I work on a really big (3 million lines of code) J2EE web application. I've been out of college for 2 years and I pretty much know that big corporate life isn't for me. There is a career opportunity to work for a small company that has a lot of funding and huge potential to sell their main project to this huge company I work for.This company makes kiosk software and works with a nearby kiosk software company. The deal isn't done, but I would come straight in to work on this project. This would be more of a interactive media position and I would do the development in flash/action script. I personally think this will be more interesting work then what I do now. This company does have other clients right now, just not on the scale of this potential huge client. I was told that my initial salary would be equal to what I'm making now, but if we land this client it could go up a lot more. I have a wife and child which should and will play a part in my decision if I should take this job. We do though have family that if crap hit the fan we could live with until we got back on our feet. So with the information provided, does this sound like a good opportunity and should I take it? This is a huge decision and the reason I'm asking the question here is because there are a lot of people here that have probably faced this decision before.

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• How can I check if a user has written his username and password correctly?

  - by Sergio Tapia

  I'm using a Linq-to-SQL class called Scans.dbml. In that class I've dragged a table called Users (username, password, role) onto the graphic area and now I can access User object via a UserRepository class: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Scanner.Classes { public class UserRepository { private ScansDataContext db = new ScansDataContext(); public User getUser(string username) { return db.Users.SingleOrDefault(x => x.username == username); } public bool exists(string username) { } } } Now in my Login form, I want to use this Linq-to-SQL goodness to do all the data related activities. UserRepository users = new UserRepository(); private void btnLogin_Click(object sender, EventArgs e) { loginToSystem(); } private void loginToSystem() { if (users.getUser(txtUsername.Text)) { } //If txtUsername exists && User.password == Salt(txtPassword) //then Show.MainForm() with User.accountType in constructor to set permissions. } I need help with verifying that a user exists && that that users.password is equal to SALT(txtpassword.text). Any guidance please?

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• invasive vs non-invasive ref-counted pointers in C++

  - by anon

  For the past few years, I've generally accepted that if I am going to use ref-counted smart pointers invasive smart pointers is the way to go -- However, I'm starting to like non-invasive smart pointers due to the following: I only use smart pointers (so no Foo* lying around, only Ptr) I'm starting to build custom allocators for each class. (So Foo would overload operator new). Now, if Foo has a list of all Ptr (as it easily can with non-invasive smart pointers). Then, I can avoid memory fragmentation issues since class Foo move the objects around (and just update the corresponding Ptr). The only reason why this Foo moving objects around in non-invasive smart pointers being easier than invasive smart pointers is: In non-invasive smart pointers, there is only one pointer that points to each Foo. In invasive smart pointers, I have no idea how many objects point to each Foo. Now, the only cost of non-invasive smart pointers ... is the double indirection. [Perhaps this screws up the caches]. Does anyone have a good study of expensive this extra layer of indirection is?

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• Fitting title for my position

  - by lithander

  In the last 2 years my company has developed a boxed and full-price computer game. All the software development has been done collaboratively by me and my co-developer. We know each other from university and got hired at the same day to equal conditions and we share the same responsibilites including the decisions of what technology to license and how to spend development resources and even how team-workflow is organized. But I struggle to find the correct wording for my position. Can I call myself a senior developer with only 3 years working-experience? Can I call myself lead programmer if I don't really have a team to "lead"? All these fancy names used in the industry (Technical Lead, Development Lead, Software Architect) seem to imply that you aren't actually coding anymore or have staff under you. On the other hand titles like "Programmer" or "Software Engineer" seem to imply that there's someone between you and the project management. That makes it hard to fill out a resume or even the badges you typically wear on conferences... people tend to judge you by your title and I'd like to avoid confusion where possible.

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• Creating a Function in SQL Server with a Phone Number as a parameter and returns a Random Number

  - by Emer

  Hi Guys, I am hoping someone can help me here as google is not being as forthcoming as I would have liked. I am relatively new to SQL Server and so this is the first function I have set myself to do. The outline of the function is that it has a Phone number varchar(15) as a parameter, it checks that this number is a proper number, i.e. it is 8 digits long and contains only numbers. The main character I am trying to avoid is '+'. Good Number = 12345678 Bad Number = +12345678. Once the number is checked I would like to produce a random number for each phone number that is passed in. I have looked at substrings, the like operator, Rand(), left(), Right() in order to search through the number and then produce a random number. I understand that Rand() will produce the same random number unless alterations are done to it but right now it is about actually getting some working code. Any hints on this would be great or even point me towards some more documentation. I have read books online and they haven't helped me, maybe I am not looking in the right places. Here is a snippet of code I was working on the Rand declare @Phone Varchar (15) declare @Counter Varchar (1) declare @NewNumber Varchar(15) set @Phone = '12345678' set @Counter = len(@Phone) while @Counter > 0 begin select case when @Phone like '%[0-9]%' then cast(rand()*100000000 as int) else 'Bad Number' end set @counter = @counter - 1 end return Thanks for the help in advance Emer

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• NSURLConnection receives data even if no data was thrown back

  - by Anna Fortuna

  Let me explain my situation. Currently, I am experimenting long-polling using NSURLConnection. I found this and I decided to try it. What I do is send a request to the server with a timeout interval of 300 secs. (or 5 mins.) Here is a code snippet: NSURL *url = [NSURL URLWithString:urlString]; NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLCacheStorageAllowedInMemoryOnly timeoutInterval:300]; NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&resp error:&err]; Now I want to test if the connection will "hold" the request if no data was thrown back from the server, so what I did was this: if (data != nil) [self performSelectorOnMainThread:@selector(dataReceived:) withObject:data waitUntilDone:YES]; And the function dataReceived: looks like this: - (void)dataReceived:(NSData *)data { NSLog(@"DATA RECEIVED!"); NSString *string = [NSString stringWithUTF8String:[data bytes]]; NSLog(@"THE DATA: %@", string); } Server-side, I created a function that will return a data once it fits the arguments and returns none if nothing fits. Here is a snippet of the PHP function: function retrieveMessages($vardata) { if (!empty($vardata)) { $result = check_data($vardata) //check_data is the function which returns 1 if $vardata //fits the arguments, and 0 if it fails to fit if ($result == 1) { $jsonArray = array('Data' => $vardata); echo json_encode($jsonArray); } } } As you can see, the function will only return data if the $result is equal to 1. However, even if the function returns nothing, NSURLConnection will still perform the function dataReceived: meaning the NSURLConnection still receives data, albeit an empty one. So can anyone help me here? How will I perform long-polling using NSURLConnection? Basically, I want to maintain the connection as long as no data is returned. So how will I do it? NOTE: I am new to PHP, so if my code is wrong, please point it out so I can correct it.

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• In a class with no virtual methods or superclass, is it safe to assume (address of first member vari

  - by Jeremy Friesner

  Hi all, I made a private API that assumes that the address of the first member-object in the class will be the same as the class's this-pointer... that way the member-object can trivially derive a pointer to the object that it is a member of, without having to store a pointer explicitly. Given that I am willing to make sure that the container class won't inherit from any superclass, won't have any virtual methods, and that the member-object that does this trick will be the first member object declared, will that assumption hold valid for any C++ compiler, or do I need to use the offsetof() operator (or similar) to guarantee correctness? To put it another way, the code below does what I expect under g++, but will it work everywhere? class MyContainer { public: MyContainer() {} ~MyContainer() {} // non-virtual dtor private: class MyContained { public: MyContained() {} ~MyContained() {} // Given that the only place Contained objects are declared is m_contained // (below), will this work as expected on any C++ compiler? MyContainer * GetPointerToMyContainer() { return reinterpret_cast<MyContainer *>(this); } }; MyContained m_contained; // MUST BE FIRST MEMBER ITEM DECLARED IN MyContainer int m_foo; // other member items may be declared after m_contained float m_bar; };

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• Function with parameter type that has a copy-constructor with non-const ref chosen?

  - by Johannes Schaub - litb

  Some time ago I was confused by the following behavior of some code when I wanted to write a is_callable<F, Args...> trait. Overload resolution won't call functions accepting arguments by non-const ref, right? Why doesn't it reject in the following because the constructor wants a Test&? I expected it to take f(int)! struct Test { Test() { } // I want Test not be copyable from rvalues! Test(Test&) { } // But it's convertible to int operator int() { return 0; } }; void f(int) { } void f(Test) { } struct WorksFine { }; struct Slurper { Slurper(WorksFine&) { } }; struct Eater { Eater(WorksFine) { } }; void g(Slurper) { } void g(Eater) { } // chooses this, as expected int main() { // Error, why? f(Test()); // But this works, why? g(WorksFine()); } Error message is m.cpp: In function 'int main()': m.cpp:33:11: error: no matching function for call to 'Test::Test(Test)' m.cpp:5:3: note: candidates are: Test::Test(Test&) m.cpp:2:3: note: Test::Test() m.cpp:33:11: error: initializing argument 1 of 'void f(Test)' Can you please explain why one works but the other doesn't?

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• Concise C# code for gathering several properties with a non-null value into a collection?

  - by stakx

  A fairly basic problem for a change. Given a class such as this: public class X { public T A; public T B; public T C; ... // (other fields, properties, and methods are not of interest here) } I am looking for a concise way to code a method that will return all A, B, C, ... that are not null in an enumerable collection. (Assume that declaring these fields as an array is not an option.) public IEnumerable<T> GetAllNonNullAs(this X x) { // ? } The obvious implementation of this method would be: public IEnumerable<T> GetAllNonNullAs(this X x) { var resultSet = new List<T>(); if (x.A != null) resultSet.Add(x.A); if (x.B != null) resultSet.Add(x.B); if (x.C != null) resultSet.Add(x.C); ... return resultSet; } What's bothering me here in particular is that the code looks verbose and repetitive, and that I don't know the initial List capacity in advance. It's my hope that there is a more clever way, probably something involving the ?? operator? Any ideas?

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• Evaluating Javascript Arrays

  - by FailBoy

  I have an array that contains an array of arrays if that makes any sense. so for example: [[1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6]] I want to see whether an array exists withing the array, so if [1, 2, 3] is duplicated at all. I have tried to use the .indexOf method but it does find the duplicate. I have also tried Extjs to loop through the array manually and to evaluate each inner array, this is how I did it: var arrayToSearch = [[1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6]]; var newArray = [1, 2, 3]; Ext.each(arrayToSearch, function(entry, index){ console.log(newArray, entry); if(newArray == entry){ console.log(index); }; }); This also does not detect the duplicate. the console.log will output [1, 2, 3] and [1, 2, 3] but will not recognize them as equal. I have also tried the === evaluator but obviously since == doesn't work the === wont work. I am at wits end, any suggestions.

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• How to check if two records have a self-referencing relation?

  - by Machine

  Consider the following schema with users and their collegues (friends): Users User: columns: user_id: name: user_id as userId type: integer(8) unsigned: 1 primary: true autoincrement: true first_name: name: first_name as firstName type: string(45) notnull: true last_name: name: last_name as lastName type: string(45) notnull: true email: type: string(45) notnull: true unique: true relations: Collegues: class: User local: invitor foreign: invitee refClass: CollegueStatus equal: true onDelete: CASCADE onUpdate: CASCADE Join table: CollegueStatus: columns: invitor: type: integer(8) unsigned: 1 primary: true invitee: type: integer(8) unsigned: 1 primary: true status: type: enum(8) values: [pending, accepted, denied] default: pending notnull: true Now, let's say I two records, one for the user making a HTTP request (the logged in user), and one record for a user he wants to send a message to. I want to check if these users are collegues. Questions: Does Doctrine have any pre-build functionality to check if two records with with self-relations are related? If not, how would you write a method to check this? Where would you put said method? (In the User-class, UserTable-class etc) I could probably do something like this: public function (User $user1, User $user2) { // Ensure we load collegues if $user1 was fetched with DQL that // doesn't load this relation $collegues = $user1->get('Collegues'); $areCollegues = false; foreach($collegues as $collegue) { if($collegue['userId'] === $user2['userId']) { $areCollegues = true; break; } } return $areCollegues; } But this looks a neither efficient nor pretty. I just feel that it should be solved already for self-referencing relations to be nice to use.

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• Syntactical analysis with Flex/Bison part 2

  - by Imran

  Hallo, I need help in Lex/Yacc Programming. I wrote a compiler for a syntactical analysis for inputs of many statements. Now i have a special problem. In case of an Input the compiler gives the right output, which statement is uses, constant operator or a jmp instructor to which label, now i have to write so, if now a if statement comes, first the first command (before the else) must be give out when the assignment of the if is yes then it must jump to the end because the command after the else isnt needed, so after this jmp then the second command must be give out. I show it in an example maybe you understand what i mean. Input adr. Output if(x==0) 10 if(x==0) Wait 5 20 WAIT 5 else 30 JMP 50 Wait 1 40 WAIT 1 end 50 END like so. I have an idea, maybe i can do it whith a special if statement like IF exp jmp_stmt_end stmt_seq END when the if statement is given in the input the compiler has to recognize the end ofthe statement and like my jmp_stmt in my compiler ( you have to download the files from http://bitbucket.org/matrix/changed-tiny) only to jump to the end. I hope you understand my problem.thanks.

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• Find records IN BETWEEN Date Range

  - by Muhammad Kashif Nadeem

  Please see attached image I have a table which have FromDate and ToDate. FromDate is start of some event and ToDate is end of taht event. I need to find a record if search criteria is in between range of dates. e.g. If a record has FromDate 2010/15/5 and ToDate 2010/15/25 and my criteria is FromDate 2010/5/18 and ToDate is 2010/5/21 then this record should be in search results becasue this is in the range of 15 to 25. Following is my search query (chunk of) SELECT m.EventId FROM MajorEvents WHERE ( (m.LocationID = @locationID OR @locationID IS NULL) OR M.LocationID IS NULL) AND ( CONVERT(VARCHAR(10),M.EventDateFrom,23) BETWEEN CONVERT(VARCHAR(10),@DateTimeFrom,23) AND CONVERT(VARCHAR(10),@DateTimeTo,23) OR CONVERT(VARCHAR(10),M.EventDateTo,23) BETWEEN CONVERT(VARCHAR(10),@DateTimeFrom,23) AND CONVERT(VARCHAR(10),@DateTimeTo,23) ) If Search Criteria is equal to FromDate or ToDate then results are ok e.g. If search criterai is DateFrom = 2010/5/15 AND DateTo = 2010/5/18 then this record will return becasue Date From is exactly what is DateFrom in db. OR If search criterai is DateFrom = 2010/5/22 AND DateTo = 2010/5/25 then this record will return becasue Date To is exactly what is DateTo in db But if anything in between this range it does not work Thanks for the help.

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• Javascript and rendering pauses and stays paused on scroll in the android browser

  - by user357303

  Hi. I've found some wierd behaviour related to scrolling and rendering and javascript. How to make it happen: On any webpage that is long enough to scroll on. Start to scroll pretty fast (fling the page). then release the touch. No while the page is still scrolling because of the momentum. Tap the screen to stop the scroll. This make the browser enter a wierd mode. On the nexus one it behaves like this: The updating of what's shown on the screen stops, you can still click on links and the go to where they are supposed to but what's shown on the screen stays the same. If you then scroll the screen a bit the update of the screen kicks in again and what you you where suppsed to see all the time is shown. On all phones with HTC Sense I've tried (Hero, Desire, Legend) this happens: The updating of the screen is stopped just like on the nexus one, but also the execution of any javascript is stopped. If you click on a link that takes you to another page however things return to normal again. The way I tested this was I created a page like this: http://pastebin.ca/1881620 The changeColor function simply changed the background color of 'container' to a few different colors. So before the error what happens is that when you click any link the color changes. after the error this happens: Nexus one: when you click on the links nothing happens (except the "orange link selected rounded corner box thing" is shown as if the link is clicked). Then when you scroll abit. You can see the color has changed (and equal amount of times to the number of times I clicked the link). On Sense: The links take me to google.com Has anyone else noticed this problem? Is there anyway to work around it? Thanks.

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• Reading Unicode files line by line C++

  - by Roger Nelson

  What is the correct way to read Unicode files line by line in C++? I am trying to read a file saved as Unicode (LE) by Windows Notepad. Suppose the file contains simply the characters A and B on separate lines. In reading the file byte by byte, I see the following byte sequence (hex) : FE FF 41 00 0D 00 0A 00 42 00 0D 00 0A 00 So 2 byte BOM, 2 byte 'A', 2byte CR , 2byte LF, 2 byte 'B', 2 byte CR, 2 byte LF . I tried reading the text file using the following code: std::wifstream file("test.txt"); file.seekg(2); // skip BOM std::wstring A_line; std::wstring B_line; getline(file,A_line); // I get "A" getline(file,B_line); // I get "\0B" I get the same results using operator instead of getline file >> A_line; file >> B_line; It appears that the single byte CR character is is being consumed only as the single byte. or CR NULL LF is being consumed but not the high byte NULL. I would expect wifstream in text mode would read the 2byte CR and 2byte LF. What am I doing wrong? It does not seem right that one should have to read a text file byte by byte in binary mode just to parse the new lines.

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• How to solve the delay problem in animation of sprites ?

  - by srikanth rongali

  My problem is, I did coding for a sprite. It should change it should change it's image from( 1, 2, 3). It should look like count down time to start a game. 1, 2, 3 are 3 png images. But the images are not displayed in equal intervals of time. I mean time between (1 - 2), (2 - 3) is not same. It is random. Please help me with my problem. Help me if there is better solution than what I am doing.(My animation should be like, before any game starts we see count down 1 then 2 then 3 then GO). -(id)init { if((self = [super init])) { [[CCDirector sharedDirector] setAnimationInterval:60.0/60]; [[CCDirector sharedDirector] setDisplayFPS:NO]; CCAnimation* numberAnimation = [CCAnimation animationWithName:@"countDown" delay: 60.0/60]; for( int i=1;i<4;i++) [numberAnimation addFrameWithFilename: [NSString stringWithFormat:@"number_%02d.png", i]]; id numberAction = [CCAnimate actionWithAnimation: numberAnimation restoreOriginalFrame:NO]; id action2 = [CCFadeOut actionWithDuration:0.5f]; CCSprite *number; number = [CCSprite spriteWithFile:@"number.png"]; .... } }

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• How to produce 64 bit masks?

  - by egiakoum1984

  Based on the following simple program the bitwise left shit operator works only for 32 bits. Is it true? #include <iostream> #include <stdlib.h> using namespace std; int main(void) { long long currentTrafficTypeValueDec; int input; cout << "Enter input:" << endl; cin >> input; currentTrafficTypeValueDec = 1 << (input - 1); cout << currentTrafficTypeValueDec << endl; cout << (1 << (input - 1)) << endl; return 0; } The output of the program: Enter input: 30 536870912 536870912 Enter input: 62 536870912 536870912 How could I produce 64-bit masks?

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• Empty Postbacks on ASP.NET pages

  - by AaronLS

  We are having a problem that seems to only be a problem when accessing our websites from internal intranet machines. When logged into the domain, and accessing our websites, postbacks are not working. Basically the page behaves as if it were refreshed and nothing was changed. When logging the GETs and POSTs with an HTTP analyzer, the post is complete empty and the ContentLength is 0. It is also very sporadic, but seems to be happening fairly often. In the case where it failed, we could see that there was an extra item in the Header for the POST, it was "Authorization" and the value was the word "Negotiate " followed by a space and then a bunch of characters and two equal symbols at the end, which looked like some kind of base64 encoded value. In a case where it succeeded, this Authorization item was no in the header, but I have logged more than one successful cases to know if that is consistent. We have seen this occur only with IE8 so far, and when it occurs it is sometimes sporadic. I can close and open the browser and it will begin working sometimes, and other times it is still broken. What might be causing the postback to be empty? This means the viewstate is not sent to the server which makes the page basically broken. It seems to certainly be a client side issue, but not sure if it's not aggravated by some server settings. Thanks in advance.

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• Few Basic Questions in Overriding

  - by Dahlia

  I have few problems with my basic and would be thankful if someone can clear this. What does it mean when I say base *b = new derived; Why would one go for this? We very well separately can create objects for class base and class derived and then call the functions accordingly. I know that this base *b = new derived; is called as Object Slicing but why and when would one go for this? I know why it is not advisable to convert the base class object to derived class object (because base class is not aware of the derived class members and methods). I even read in other StackOverflow threads that if this is gonna be the case then we have to change/re-visit our design. I understand all that, however, I am just curious, Is there any way to do this? class base { public: void f(){cout << "In Base";} }; class derived:public base { public: void f(){cout << "In Derived";} }; int _tmain(int argc, _TCHAR* argv[]) { base b1, b2; derived d1, d2; b2 = d1; d2 = reinterpret_cast<derived*>(b1); //gives error C2440 b1.f(); // Prints In Base d1.f(); // Prints In Derived b2.f(); // Prints In Base d1.base::f(); //Prints In Base d2.f(); getch(); return 0; } In case of my above example, is there any way I could call the base class f() using derived class object? I used d1.base()::f() I just want to know if there any way without using scope resolution operator? Thanks a lot for your time in helping me out!

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• Do COM Dll References Require Manual Disposal? If so, How?

  - by Drew

  I have written some code in VB that verifies that a particular port in the Windows Firewall is open, and opens one otherwise. The code uses references to three COM DLLs. I wrote a WindowsFirewall class, which Imports the primary namespace defined by the DLLs. Within members of the WindowsFirewall class I construct some of the types defined by the DLLs referenced. The following code isn't the entire class, but demonstrates what I am doing. Imports NetFwTypeLib Public Class WindowsFirewall Public Shared Function IsFirewallEnabled as Boolean Dim icfMgr As INetFwMgr icfMgr = CType(System.Activator.CreateInstance(Type.GetTypeFromProgID("HNetCfg.FwMgr")), INetFwMgr) Dim profile As INetFwProfile profile = icfMgr.LocalPolicy.CurrentProfile Dim fIsFirewallEnabled as Boolean fIsFirewallEnabled = profile.FirewallEnabled return fIsFirewallEnabled End Function End Class I do not reference COM DLLs very often. I have read that unmanaged code may not be cleaned up by the garbage collector and I would like to know how to make sure that I have not introduced any memory leaks. Please tell me (a) if I have introduced a memory leak, and (b) how I may clean it up. (My theory is that the icfMgr and profile objects do allocate memory that remains unreleased until after the application closes. I am hopeful that setting their references equal to nothing will mark them for garbage collection, since I can find no other way to dispose of them. Neither one implements IDisposable, and neither contains a Finalize method. I suspect they may not even be relevant here, and that both of those methods of releasing memory only apply to .Net types.)

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• Counting entries in a list of dictionaries: for loop vs. list comprehension with map(itemgetter)

  - by Dennis Williamson

  In a Python program I'm writing I've compared using a for loop and increment variables versus list comprehension with map(itemgetter) and len() when counting entries in dictionaries which are in a list. It takes the same time using a each method. Am I doing something wrong or is there a better approach? Here is a greatly simplified and shortened data structure: list = [ {'key1': True, 'dontcare': False, 'ignoreme': False, 'key2': True, 'filenotfound': 'biscuits and gravy'}, {'key1': False, 'dontcare': False, 'ignoreme': False, 'key2': True, 'filenotfound': 'peaches and cream'}, {'key1': True, 'dontcare': False, 'ignoreme': False, 'key2': False, 'filenotfound': 'Abbott and Costello'}, {'key1': False, 'dontcare': False, 'ignoreme': True, 'key2': False, 'filenotfound': 'over and under'}, {'key1': True, 'dontcare': True, 'ignoreme': False, 'key2': True, 'filenotfound': 'Scotch and... well... neat, thanks'} ] Here is the for loop version: #!/usr/bin/env python # Python 2.6 # count the entries where key1 is True # keep a separate count for the subset that also have key2 True key1 = key2 = 0 for dictionary in list: if dictionary["key1"]: key1 += 1 if dictionary["key2"]: key2 += 1 print "Counts: key1: " + str(key1) + ", subset key2: " + str(key2) Output for the data above: Counts: key1: 3, subset key2: 2 Here is the other, perhaps more Pythonic, version: #!/usr/bin/env python # Python 2.6 # count the entries where key1 is True # keep a separate count for the subset that also have key2 True from operator import itemgetter KEY1 = 0 KEY2 = 1 getentries = itemgetter("key1", "key2") entries = map(getentries, list) key1 = len([x for x in entries if x[KEY1]]) key2 = len([x for x in entries if x[KEY1] and x[KEY2]]) print "Counts: key1: " + str(key1) + ", subset key2: " + str(key2) Output for the data above (same as before): Counts: key1: 3, subset key2: 2 I'm a tiny bit surprised these take the same amount of time. I wonder if there's something faster. I'm sure I'm overlooking something simple. One alternative I've considered is loading the data into a database and doing SQL queries, but the data doesn't need to persist and I'd have to profile the overhead of the data transfer, etc., and a database may not always be available. I have no control over the original form of the data. The code above is not going for style points.

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