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  • converting ip to long string in mysql command !

    - by Mac Taylor
    hey guys I'm trying to use ip2country technique to show my users'flags simple thing to do is to write a sql statement and show users from session table and then query to see if their ip is in what range and show their flags it simple but dengerous becuase when showing 300 users online and fetching from session table and then query once again ip2country table to get the flags there will be surelly memory overusage problem now i wrote a query to make it in one query : SELECT s.session_ip,ipc.* FROM session s left join ip2country ipc ON ipc.ip_lo<=s.session_ip AND ipc.ip_hi>=s.session_ip WHERE s.session_time > '".( time() - 60) )."' now its clear above query is wrong cause ips saved in ip2country table is long string 1000013824 and ips saved in session table are real ip e.g. 193.169.0.0 now i know how to convert from ip to long in php ip2long() but is there any command in mysql to do it with out building another query !?

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  • What could cause a returning function to crash? C++

    - by JeanOTF
    So I have been debugging this error for hours now. I writing a program using Ogre3d relevant only because it doesn't load symbols so it doesn't let me stack trace which made finding the location of the crash even harder. So, write before I call a specific function I print out "Starting" then I call the function and immediately after I print "Stopping". Throughout the function I print out letters A-F where F is printed right before the function returns (one line above the last '}') The weird thing is when the crash occurs it is after the 'F' is printed but there is no 'Stopping'. Does this mean that the crash is happening in between somewhere? The only thing I can think of is something going wrong during the deallocation of some of the memory allocated during the function. I've never had anything happen like this, I will keep checking to make sure it's going wrong where I think it is.

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  • Clone a 'link' in SWT

    - by Steve
    I have a table of information that includes a username, an ip address, and a timestamp. What I wanted to do was to have the ip address contained within a link object that when the link is clicked it utilizes bgp.he.net to get information about the host/IP address. I have tried creating threads to resolve the IP addresses but it is often a large amount of IP addresses and I read that InetAddress#getByName isn't non-blocking, so I figured having links that go to this site is the next best thing. Question is: Is it possible to have links for each of my IP addresses in the table without creating a new link object for each row? I don't know how bad that would be on memory usage which is why I'm inquiring about cloning an instance of an IP and having the link open bgp.he.net/link.getText()

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  • Reason for .Net UI Element Thread-restriction

    - by Charles Bretana
    We know that it is not possible to execute code that manipulates the properties of any UI element from any thread other than the thread the element was instantiated on... My question is why? I remember that when we used COM user interface elements, (in COM/VB6 days), that all UI elements were created using COM classes and co-classes that stored their resources using a memory model referred to as Thread-Local-Storage (TLS) , but as I recall, this was required because of something relaetd to the way COM components were constructed, and should not be relevant to .Net UI elements. Wha's the underlying reason why this restriction still exists? Is it because the underlying Operating System still uses COM-based Win32 API classes for all UI elements, even the ones manipulated in a managed .Net application ??

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  • In Perl, can I limit the length of a line as I read it in from a file (like fgets)

    - by SB
    I'm trying to write a piece of code that reads a file line by line and stores each line, up to a certain amount of input data. I want to guard against the end-user being evil and putting something like a gig of data on one line in addition to guarding against sucking in an abnormally large file. Doing $str = <FILE> will still read in a whole line, and that could be very long and blow up my memory. fgets lets me do this by letting me specify a number of bytes to read during each call and essentially letting me split one long line into my max length. Is there a similar way to do this in perl? I saw something about sv_gets but am not sure how to use it (though I only did a cursory Google search). Thanks.

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  • C# array problem

    - by user208080
    Hi there. I am a newbie in C# and here are 2 questions: I have a 2d array a[3,3], how can I express one dimension as a new array and pass to some function. i.e. int[,] a = new int[3,3]; a[0,0] = 1; ... string b = concatenate(a[0]); // where concatenate is a function take a one dimension array as param Can I create a 65000x65000 array with C#? I got some "out of memory" error. Thanks in advance.

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  • Quick way to get an NSDictionary from an XML NSData representation?

    - by dontWatchMyProfile
    I've loaded an XML file as NSData into memory and parse over the elements using NSXMLParser. Although it works, it's a very ugly and hard to maintain code since there are about 150 different elements to parse. I know there are nice third-party solutions, but I want to keep it with the iPhone SDK for purpose of practice and fun. So I thought: Why not convert that XML file into an NSDictionary? Having this, I could use fast enumeration to go over the elements. Or is it just the same amount of ugly code needed to parse and process an XML right away with NSXMLParser? Would I build up an NSDictionary for every found node in the XML and create a huge one, containing the whole structure and data? Or is there an even simpler way?

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  • soft stoppped working

    - by Jack Morton
    this is might be really weird, but I have no idea what kinda wizardry of this. Basically, my Visual Studio stopped responding to my changes, it stopped building solution. I can comment code, which would completely ruin the logic of program, and Visual Studio will still run program that I guess it has in memory. It's really annoying, and I have no idea what it is. I keep restarting software, but it's still does the same. It's a licensed software. I was wondering If someone knew what was going on. Thanks!

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  • Volatile keyword

    - by Tiyoal
    Say I have two threads and an object. One thread assigns the object: public void assign(MyObject o) { myObject = o; } Another thread uses the object: public void use() { myObject.use(); } Does the variable myObject have to be declared as volatile? I am trying to understand when to use volatile and when not, and this is puzzling me. Is it possible that the second thread keeps a reference to an old object in its local memory cache? If not, why not? Thanks a lot.

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  • Speed of running a test suite in Rails

    - by Milan Novota
    I have 357 tests (534 assertions) for my app (using Shoulda). The whole test suite runs in around 80 seconds. Is this time OK? I'm just curious, since this is one of my first apps where I write tests extensively. No fancy stuff in my app. Btw.: I tried to use in memory sqlite3 database, but the results were surprisingly worse (around 83 seconds). Any clues here? I'm using Macbook with 2GB of RAM and 2GHz Intel Core Duo processor as my development machine.

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  • Returning the address of local or temporary variable

    - by Dave18
    #include <iostream> int& foo() { int i = 6; std::cout << &i << std::endl; return i; } int main() { int i = foo(); std::cout << &i << std::endl; } I know it doesn't return the address of local variable so that is why the warning but why does it still works and assign the variable i in main() to '6'? How does it only return the value if the variable the was removed from stack memory?

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  • Operations on 64bit words in 32bit system

    - by Vilo
    I'm new here same as I'm new with assembly. I hope that you can help me to start. I'm using 32bit (i686) Ubuntu to make programs in assembly, using gcc compiler. I know that general-purpose-registers are 32bit (4 bytes) max, but what when I have to operate on 64 bit numbers? Intel's instruction says that higher bits are stored in %edx and lower in %eax Great... So how can I do something with this 2-registers number? I have to convert 64bit dec to bin, then save it to memory and show on the screen. How to make the 64bit quadword at start of the program in .data section?

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  • PHP find if file data is an image

    - by Christian Sciberras
    Imagine I have some file data in a variable $data. I need to determine whether it is an image or not. No need for details such as corrupt images etc. Firs thought would be getting the file mime type by looking at the magic number and then see whether "image" is in the mime type. No such luck, even if I have a "file extension to mime type" script, I don't have a reliable way to get mime from magic number. My next option was to have a reasonable list of image file magic numbers and consult them. However, it relatively difficult to find such magic numbers (gif for instance has different magic numbers, some of which could pretty rare - if memory serves me right). A better idea would be some linux program which can do this kind of thing. Any ideas? I'm running RHEL and PHP 5.3. I've got root access - ie able to install stuff if needed. - Chris.

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  • Is there a way to read 10000 lines from a file in python?

    - by windsound
    I am relatively new in python, was working on C a lot. Since I was seeing so many new functions in python that I do not know, I was wondering if there is a function that can request 10000 lines from a file in python. Something like this is what I expect if that kind of function exist: lines = get_10000_lines(file_pointer) Did python have a build-in function or is there any module that I can download for this? If not, how do I do this to be easiest way. I need to analyze a huge file so I want to read 10000 lines and analyze per time to save memory. Thanks for helping!

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  • Does a servlet-based stack have significant overheads?

    - by John
    I don't know if it's simply because page-loads take a little time, or the way servlets have an abstraction framework above the 'bare metal' of HTTP, or just because of the "Enterprise" in Jave-EE, but in my head I have the notion that a servlet-based app is inherently adding overhead compared to a Java app which simply deals with sockets directly. Forget web-pages, imagine instead a Java server app where you send it a question over an HTTP request and it looks up an answer from memory and returns the answer in the response. You can easily write a Java socket-based app which does this, you can also do a servlet approach and get away from the "bare metal" of sockets. Is there any measurable performance impact to be expected implementing the same approach using Servlets rather than a custom socket-based HTTP listening app? And yes, I am hazy on the exact data sent in HTTP requests and I know it's a vague question. It's really about whether servlet implementations have lots of layers of indirection or anything else that would add up to a significant overhead per call, where by significant I mean maybe an additional 0.1s or more.

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  • C/C++ function definitions without assembly

    - by Jack
    Hi, I always thought that functions like printf() are in the last step defined using inline assembly. That deep into stdio.h is burried some asm code that actually tells CPU what to do. Something like in dos, first mov bagining of the string to some memory location or register and than call some int. But since x64 version of Visual Studio doesent support inline assembler at all, it made me think that there are really no assembler-defined functions in C/C++. So, please, how is for example printf() defined in C/C++ without using assembler code? What actually executes the right software interrupt? Thanks.

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  • What are the disadvantages of using a StringBuilder?

    - by stickman
    I know that StringBuilder is more efficient than a normal string when processing code which modifies the string value a lot because although strings act like value types, they are actually reference, which makes them immutable so every time we change it, we need to create a new reference in memory. My question is that, why doesn't .NET just use stringBuilder by default? There must be some disadvantages of it over just using String. Can anyone tell me what they are? The only thing I can think of is perhaps it is a heavier object and it takes more time to instantiate so if you aren't changing the string too much, this would override the benefits of StringBuilder

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  • Trying to use tcl threads on windows 7 results in access violation.

    - by Juan
    I'm trying to get this simple program to work on windows, but it crashes: unsigned (__stdcall testfoo)(ClientData x) { return 0; } int main() { Tcl_ThreadId testid = 0; Tcl_CreateThread(&testid, testfoo, (ClientData) NULL, TCL_THREAD_STACK_DEFAULT, TCL_THREAD_NOFLAGS); } I am using a makefile generated by cmake and linking against a version of Tcl 8.5.7 I compiled myself using Visual C++ 2008 express. It was compiled using msvcrt,static,threads and the name of the resulting library is tcl85tsx.lib. The error is: Unhandled exception at 0x77448c39 in main.exe: 0xC0000005: Access violation writing location 0x00000014. The Tcl library works fine, and I can even run a threading script example by loading the Thread extension into it. My assumption is that there is something horribly wrong with a memory violation, but I have no idea what. Any help appreciated.

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  • Efficient questions

    - by rayman
    Hi, I have to manage xml's and Strings in my app. by efficenty and memory saving, is collection(ArrayList) will be much more 'expensive' then array of Strings? another issue is: i could use the content as regular String, or XML.. is working with XML also makes it more 'expensive' ? when i say i expensive i talk about taking system sources. please tell me by any of your exprience if the diffrences are significant? thanks, ray.

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  • Best way to have unique key over 500M varchar(255) records in mysql/innodb?

    - by taw
    I have url column with unique key over it - but its performance on updates is absolutely atrocious. I suspect that's because the index doesn't all fit in memory. So I was thinking, how about adding a column of md5(url) with 16 bytes of binary data and unique-keying that instead. What would be the best datatype for that? I'd love to be able to just see 32-character hex hash, while mysql would convert it to/from 16 binary bytes and index that, as programs using the database might have some troubles with arbitrary binary data that I'd rather avoid if possible (also I'm a bit afraid that mysql might get some strange ideas about character sets and for example overalocating storage for that by 3:1 because it thinks it might need utf8, how do I avoid that for cure?).

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  • Updating a database periodically with Java

    - by MSR
    I would like to perform updates to a MySQL database using two separate classes (that do different things) -- one doing so every 10 seconds, and the second every minute. I have a few gaps in my Java knowledge and I'm wondering what the best way to achieve it is. Importantly, if connectivity to the database is lost, I need reconnection attempts to occur indefinitely, and I'm guessing the use of Prepared Statements will make queries more efficient. Should the connection to the database be left open all the time or closed between the updates being run? Maybe I also need to think about clearing objects/resources out of memory if the class instances are going to be run indefinitely.

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  • C# how to store those information?

    - by 5YrsLaterDBA
    I have a PrivilegeGroup table, a Privileges table and a link table because the PrivilegeGroup table and the Privileges table is a many to many relationship. I am thinking about load all contents of PrivilegeGroup table and Privilege table into memory from database at beginning when application started. I want to save them in a form easily to look up. Usually we will look up the PrivilegeCode via GroupId. Which structure is good for this purpose? array of list? dictionary?

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  • Does the Internet make us less good programmers? [closed]

    - by stagas
    With all the information and code available nowadays on the Internet has that diminished our capability of remembering or learning stuff just because we know they're available somewhere out there, just a Google away or a StackOverflow question away? For example I find myself visiting php.net quite often to check the syntax of the same functions over and over again, not because my memory sucks, but I don't feel like keeping the information in me, since I know I'll find it again on the net. And about StackOverflow, isn't the process of figuring things out on your own supposed to improve your programming skills? If the answers are all just clicks away, do we actually learn something or just keep a pointer in our heads where to search for it again when we need it? Your thoughts are welcome. Hope it doesn't shut down as subjective or anything, the answers would be really interesting ;)

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  • What happens if an asynchronous delegate call never returns?

    - by RichardHowells
    I found a decent looking example of how to call a delegate asynchronously with a timeout... http://www.eggheadcafe.com/tutorials/aspnet/847c94bf-4b8d-4a66-9ae5-5b61f049019f/basics-make-any-method-c.aspx. In summary it uses WaitOne with a timeout to determine if the call does not return before the timeout expires. I also know that you should have an EndInvoke to match each BeginInvoke. So what happens if the wait timeout expires? We (presumably) DON'T want to call EndInvoke as that will block. The code can go on to do 'other things', but have we leaked anything? Is there some poor thread someplace blocked waiting for a return that's never going to happen? Have we leaked some memory where the result-that-will-never-return was going to be placed?

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  • Find node level in a tree

    - by Álvaro G. Vicario
    I have a tree (nested categories) stored as follows: CREATE TABLE `category` ( `category_id` int(10) unsigned NOT NULL AUTO_INCREMENT, `category_name` varchar(100) NOT NULL, `parent_id` int(10) unsigned DEFAULT NULL, PRIMARY KEY (`category_id`), UNIQUE KEY `category_name_UNIQUE` (`category_name`,`parent_id`), KEY `fk_category_category1` (`parent_id`,`category_id`), CONSTRAINT `fk_category_category1` FOREIGN KEY (`parent_id`) REFERENCES `category` (`category_id`) ON DELETE SET NULL ON UPDATE CASCADE ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_spanish_ci I need to feed my client-side language (PHP) with node information (child+parent) so it can build the tree in memory. I can tweak my PHP code but I think the operation would be way simpler if I could just retrieve the rows in such an order that all parents come before their children. I could do that if I knew the level for each node: SELECT category_id, category_name, parent_id FROM category ORDER BY level -- No `level` column so far :( Can you think of a way (view, stored routine or whatever...) to calculate the node level? I guess it's okay if it's not real-time and I need to recalculate it on node modification.

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