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• Known problems with filemtime() on Windows - files getting touched arbitrarily?

  - by Pekka

  Is there a known issue leading to file modification times of cache files on Windows XP SP 3 getting arbitrarily updated, but without any actual change? Is there some service on a standard Windows XP - Backup, Sync, Versioning, Virus scanner - known to touch files? They all have a .txt extension. If there isn't, forget it. Then I'm getting something wrong in my cache routines, and I'll debug my way through. Background: I'm building a simple caching wrapper around a slow web site on a Windows server. I am comparing the filemtime() time stamp to some columns in the data base to determine whether a cached file is stale. I'm having problems using this method because the modification time of the cache files seems to get updated in between operations without me doing anything. THis results in stale files being displayed. I'm the only user on the machine. The operating system is Windows XP, the webserver a XAMPP Apache 2 with PHP 5.2

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• Can this loop be sped up in pure Python?

  - by Noctis Skytower

  I was trying out an experiment with Python, trying to find out how many times it could add one to an integer in one minute's time. Assuming two computers are the same except for the speed of the CPUs, this should give an estimate of how fast some CPU operations may take for the computer in question. The code below is an example of a test designed to fulfill the requirements given above. This version is about 20% faster than the first attempt and 150% faster than the third attempt. Can anyone make any suggestions as to how to get the most additions in a minute's time span? Higher numbers are desireable. EDIT: This experiment is being written in Python 3.1 and is 15% faster than the fourth speed-up attempt. def start(seconds): import time, _thread def stop(seconds, signal): time.sleep(seconds) signal.pop() total, signal = 0, [None] _thread.start_new_thread(stop, (seconds, signal)) while signal: total += 1 return total if __name__ == '__main__': print('Testing the CPU speed ...') print('Relative speed:', start(60))

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• Time complexity O() of isPalindrome()

  - by Aran

  I have this method, isPalindrome(), and I am trying to find the time complexity of it, and also rewrite the code more efficiently. boolean isPalindrome(String s) { boolean bP = true; for(int i=0; i<s.length(); i++) { if(s.charAt(i) != s.charAt(s.length()-i-1)) { bP = false; } } return bP; } Now I know this code checks the string's characters to see whether it is the same as the one before it and if it is then it doesn't change bP. And I think I know that the operations are s.length(), s.charAt(i) and s.charAt(s.length()-i-!)). Making the time-complexity O(N + 3), I think? This correct, if not what is it and how is that figured out. Also to make this more efficient, would it be good to store the character in temporary strings?

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• Running MSBuild script on development machine

  - by devdigital

  Hi, I have an MSBuild script which performs a lot of tasks, as it is run on our build server. I want the script to be run each time a developer builds from Visual Studio on their local development machine, so that a) the build process they are runnning locally is the same as that run by the build server so any problems in the build can be identified immediately by the developer b) many of the operations of the build script are run on local builds, for example running of unit tests, generation of code coverage reports etc How is this possible in Visual Studio (2008)? Note I am running a single solution product with multiple projects.

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• Can I turn off implicit Python unicode conversions to find my mixed-strings bugs?

  - by Tal Weiss

  When profiling our code I was surprised to find millions of calls to C:\Python26\lib\encodings\utf_8.py:15(decode) I started debugging and found that across our code base there are many small bugs, usually comparing a string to a unicode or adding a sting and a unicode. Python graciously decodes the strings and performs the following operations in unicode. How kind. But expensive! I am fluent in unicode, having read Joel Spolsky and Dive Into Python... I try to keep our code internals in unicode only. My question - can I turn off this pythonic nice-guy behavior? At least until I find all these bugs and fix them (usually by adding a u'u')? Some of them are extremely hard to find (a variable that is sometimes a string...). Python 2.6.5 (and I can't switch to 3.x).

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• How might one implement FileTimeToSystemTime?

  - by Billy ONeal

  Hello :) I'm writing a simple wrapper around the Win32 FILETIME structure. boost::datetime has most of what I want, except I need whatever date type I end up using to interpolate with Windows APIs without issues. To that end, I've decided to write my own things for doing this -- most of the operations aren't all that complicated. I'm implementing the TimeSpan - like type at this point, but I'm unsure how I'd implement FileTimeToSystemTime. I could just use the system's built-in FileTimeToSystemTime function, except FileTimeToSystemTime cannot handle negative dates -- I need to be able to represent something like "-12 seconds". How should something like this be implemented? Billy3

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• Where can I find soft-multiply and divide algorithms?

  - by srking

  I'm working on a micro-controller without hardware multiply and divide. I need to cook up software algorithms for these basic operations that are a nice balance of compact size and efficiency. My C compiler port will employ these algos, not the the C developers themselves. My google-fu is so far turning up mostly noise on this topic. Can anyone point me to something informative? I can use add/sub and shift instructions. Table lookup based algos might also work for me, but I'm a bit worried about cramming so much into the compiler's back-end...um, so to speak. Thanks!

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• How to limit data to users who own it without limiting admin users in CakePHP?

  - by cdburgess

  Currently I am writing an application where I have multiple users. They have data that should only be visible to them and not the other authenticated users in the system. I also have administrators who manage the system and have access to all of the information. What is the best way to limit users to their data without limiting admin users? Currently I am using a callback to limit the queries by user, but the admin will get the same limits. So I need to know a better way to do it. More importantly, the right way to do it. For example, I want the standard user to be able to see their user information only and be limited to CRUD operations on their information only. The admin, however, should be able to see ALL users and CRUD ALL user data. Any ideas?

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• Making self-logging modules with Log::Log4perl

  - by Oesor

  Is there a way to use Log::Log4perl to make a smart self-logging module that logs its operations to a file even in the absence of the calling script not initializing Log4perl? As far as I can tell from the documentation, the only way to use Log4perl is to initialize it in the running script from a configuration, then modules implementing Log4perl calls log themselves based on the caller's Log4perl config. Instead, I'd like the modules to provide a default initialization config for Log4perl. This would provide the default file appender for the module's category. Then, I could override this behavior by initing Log4perl in the caller with a different config if needed, and everything would hopefully just work. Is this sort of defensive logging behavior possible or am I going to need to rely on initing Log4perl in every .pl script that calls the module I want logged?

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• Storing And Using Microsoft User Account Credentials in SQL Server 2008 database

  - by user337501

  I'm not exactly positive how to word this for the sake of the title so please forgive me. Also I can't seem to figure out how to even google this question, so I'm hoping that I can get a lead in the right direction. Part of my software(VB.NET App) requires the ability to access/read/write a shared network folder. I have an option for the user to specify any credentials that might be needed to access said folder. I want to store these credentials given in the SQL Server database as part of the config (I have a table which contains configuration). My concern is that the password for the user account will be unencrpyted. Yet, if I encrypt the password the VB.NET App And/Or database will be unable to use the credentials for file i/o operations unless the Password is unencrypted before use. I'm fishing for suggestions on how to better handle this situation.

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• Is there any reason why someone would want to create an Core Data model programmatically?

  - by mystify

  I wonder in which cases it would be good to make an NSManagedObjectModel completely programmatically, with NSEntityDescription instances and all this stuff. I'm that kind of person who prefers to code programmatically, rejecting Interface Builder. But when it comes to Core Data, I have a hard time figuring out why I should kill my time NOT using the nice Xcode Data Modeler tool. And since data models are stuck to a given state (except when you want to do some ugly migration operations where thinks probably go wrong and users get mad, really mad), I see no big sense in a data model that's made programmatically for the purpose of changing it all the time. Did I miss something?

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• RESTful application validation. Mix of frontend/backend validation. How?

  - by Julian Davchev

  Hi. Using RESTful for all backend persistance and operations. I just pass data from frontend (by frontend I don't mean clientside but the part that is making use of the REST) to rest and data gets back success or no with validation errors if any. Thing is I have stuff that should be validated on frontend too..like csrf tokens, captcha etc. Only reasonable way is I mix validation coming from token/captcha checks and validation errors coming back from REST. Issue with this will be kinda automation as I wouldn't want form field names to map 1:1 with backend field names use by the REST documents. Any pointers ideas are more than welcome.

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• What's exactly the nature of .Net Framework 3.5 Service Pack1?

  - by Richard77

  Hello, I did some recovery disk operations with my laptop because it became instable. Now, I'm about to re-install SQL Server 2008 Professional, but it keeps telling me that I need to install .net framework 3.5 with service pack1. What's strange is I was asked to do the same when I installed Visual Studio 2008 Professional earlier. I'd like to know: what's .Net Framework Service Pack1? is it One piece of software sitting on top of windows ? Several software having the same name so that Visual Studio has it, SQL Server also has it, and do on... And why the naming Service Pack1 behind .Net Framework? I'm really lost. Thanks for helping

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• Boost Filesystem Library Visual C++ Compile Error

  - by John Miller

  I'm having the following issue just trying to compile/run some of the example programs with the Boost Filesystem Library. I'm using MS-Visual C++ with Visual Studio .NET (2003). I've installed the Boost libraries, version 1.38 and 1.39 (just in case there was a version problem) using the BoostPro installers. If I just try to include /boost/filesystem/operations.hpp I receive the following error: \boost_1_38\boost\system\error_code.hpp(230) : error C2039: 'type' : is not a member of 'boost::enable_if<boost::system::is_error_condition_enum<Cond,boost::detail::enable_if_default_T>' Any help is greatly appreciated. Thank you!

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• Ruby - Manipulating Time/DateTime by the Hour/Day?

  - by viatropos

  Where can I find some examples on how to manipulate the time objects by days/hours/etc? I would like to do this: time.now_by_hour #=> "Tue Jun 15 23 MST 2010" time.now_by_day #=> ""Tue Jun 15 MST 2010" time.now_by_hour - 4.weeks - 3.days #=> "Sat May 15 MST 2010" What is the recommended order of operations? The reason for this is I would like to run through lists of times and sort them by date to the hour, not to the minute and second.

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• Transaction within transaction

  - by user281521

  Hello, I want to know if open a transaction inside another is safe and encouraged? I have a method: def foo(): session.begin try: stuffs except Exception, e: session.rollback() raise e session.commit() and a method that calls the first one, inside a transaction: def bar(): stuffs try: foo() #<<<< there it is :) stuffs except Exception, e: session.rollback() raise e session.commit() if I get and exception on the foo method, all the operations will be rolled back? and everything else will work just fine? thanks!!

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• Python: Huge file reading by using linecache Vs normal file access open()

  - by user335223

  Hi, I am in a situation where multiple threads reading the same huge file with mutliple file pointers to same file. The file will have atleast 1 million lines. Eachline's length varies from 500 characters to 1500 characters. There won't "write" operations on the file. Each thread will start reading the same file from different lines. Which is the efficient way..? Using the Python's linecache or normal readline() or is there anyother effient way?

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• Which database engines support IP addresses as a native type?

  - by Matt McClellan

  I'm trying to find databases with support for IP addresses as a native type (as opposed to storing as a string, or an unsigned integer, which at least one commenter has already pointed out won't work for IPv6). The primary reason I'm looking for this is ease of development. For example, sorting on a "native" IP address column would be correct (as opposed to when it's stored as a string). I would assume support for such a type would also include useful operations such as determining if an IP address is inside a specified network for use in WHERE clauses. The only one I'm aware of so far is PostgreSQL with its inet class. Does anyone have any others?

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• A 4-byte Unsigned Int for Sql Server 2008?

  - by Jeff Meatball Yang

  I understand there are multiple questions about this on SO, but I have yet to find a definitive answer of "yes, here's how..." So here it is again: What are the possible ways to store an unsigned integer value (32-bit value or 32-bit bitmap) into a 4-byte field in SQL Server? Here are ideas I have seen: 1) Use a -1*2^31 offset for all values Disadvantages: need to perform math on the values before reading/writing/aggregating. 2) Use 4 tinyint fields Disadvantages: need to concatenate values to perform any operations 3) Use binary(4) Disadvantages: actually uses 4 + 2 bytes of space

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• Fast, Vectorizable method of taking floating point number modulus of special primes?

  - by caffiend

  Is there a fast method for taking the modulus of a floating point number? With integers, there are tricks for Mersenne primes, so that its possible to calculate y = x MOD 2^31 without needing division. Can any similar tricks be applied for floating point numbers? Preferably, in a way that can be converted into vector/SIMD operations, or moved into GPGPU code. The primes I'm interested in would be 2^7 and 2^31, although if there are more efficient ones for floating point numbers, those would be welcome.

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• How to design WCF Contracts?

  - by Amitabh

  We are designing a WCF layer which can be invoked either by a Asp.Net or a WinForm application. Our Application contains too many Entities. If we design WCF Contract around these entities then we get too many Contracts e.g IPartyService, IUserService, IPaymentService etc. So, I may end up with 30-40 Contracts? Is it a good idea or should we go for one huge contracts with around 100 operations? What are the pros and cons of each approach or is there a better way.

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• Very Different Execution Times of SQL Query in C# and SQL Server Management Studio

  - by Paul

  I have a simple SQL query that when run from C# takes over 30 seconds then times-out every time, whereas when run on SQL Server Management Studio successfully completes instantly. In the latter case, a query execution plan reveals nothing troubling, and the execution time is spread nicely through a few simple operations. I've run 'EXEC sp_who2' while the query is running from C#, and it is listed as taking 29,000 milliseconds of CPU time, and is not blocked by anything. I have no idea how to begin solving this. Does anyone have some insight? The query is: SELECT c.lngId, ... FROM tblCase c INNER JOIN tblCaseStatus s ON s.lngId = c.lngId INNER JOIN tblCaseStatusType t ON t.lngId = s.lngId INNER JOIN [Another Database]..tblCompany cm ON cm.lngId = cs.lngCompanyId WHERE t.lngId = 25 AND c.IsDeleted = 0 AND s.lngStatus = 1

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• How to implement square root and exponentiation on arbitrary length numbers?

  - by tomp

  I'm working on new data type for arbitrary length numbers (only non-negative integers) and I got stuck at implementing square root and exponentiation functions (only for natural exponents). Please help. I store the arbitrary length number as a string, so all operations are made char by char. Please don't include advices to use different (existing) library or other way to store the number than string. It's meant to be a programming exercise, not a real-world application, so optimization and performance are not so necessary. If you include code in your answer, I would prefer it to be in either pseudo-code or in C++. The important thing is the algorithm, not the implementation itself. Thanks for the help.

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• static, define, and const in C

  - by yCalleecharan

  Hi, I've read that static variables are used inside function when one doesn't want the variable value to change/initialize each time the function is called. But what about defining a variable static in the main program before "main" e.g. #include <stdio.h> static double m = 30000; int main(void) { value = m * 2 + 3; } Here the variable m has a constant value that won't get modified later in the main program. In the same line of thought what difference does it make to have these instead of using the static definition: const double m = 30000; or #define m 30000 //m or M and then making sure here to use double operations in the main code so as to convert m to the right data type. Thanks a lot...

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• ContextSwitchDeadlock Was Detected error in C#

  - by assassin

  Hi, I am running a C# application, and during run-time I get the following error: The CLR has been unable to transition from COM context 0x20e480 to COM context 0x20e5f0 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time. To avoid this problem, all single threaded apartment (STA) threads should use pumping wait primitives (such as CoWaitForMultipleHandles) and routinely pump messages during long running operations. Can anyone please help me out with the problem here? Thanks a lot.

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