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  • How do I learn algorithms?

    - by Panthe
    Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be lear ning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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  • Network throughput issue (ARP-related)

    - by Joel Coel
    The small college where I work is having some very strange network issues. I'm looking for any advice or ideas here. We were fine over the summer, but the trouble began few days after students returned to campus in force for the fall term. Symptoms The main symptom is that internet access will work, but it's very slow... often to the point of timeouts. As an example, a typical result from Speedtest.net will return .4Mbps download, but allow 3 to 8 Mbps upload speed. Lesser symptoms may include severely limited performance transferring data to and from our file server, or even in some cases the inability to log in to the computer (cannot reach the domain controller). The issue crosses multiple vlans, and has effected devices on nearly every vlan we operate. The issue does not impact all machines on the network. An unaffected machine will typically see at least 11Mbps download from speedtest.net, and perhaps much more depending on larger campus traffic patterns at the time. There is one variation on the larger issue. We have one vlan where users were unable to log into nearly all of the machines at all. IT staff would log in using a local administrator account (or in some cases cached credentials), and from there a release/renew or pinging the gateway would allow the machine to work... for a while. Complicating this issue is that this vlan covers our computer labs, which use software called Deep Freeze to completely reset the hard drives after a reboot. It could just the same issue manifesting differently because of stale data on machines that have not permanently altered low-level info for weeks. We were able to solve this, however, by creating a new vlan and moving the labs over to the new vlan wholesale. Instigations Eventually we noticed that the effected machines all had recent dhcp leases. We can predict when a machine will become "slow" by watching when a dhcp lease comes up for renewal. We played with setting the lease time very short for a test vlan, but all that did was remove our ability to predict when the machine would become slow. Machines with static IPs have pretty much always worked normally. Manually releasing/renewing an address will never cause a machine to become slow. In fact, in some cases this process has fixed a machine in that state. Most of the time, though, it doesn't help. We also noticed that mobile machines like laptops are likely to become slow when they cross to new vlans. Wireless on campus is divided up into "zones", where each zone maps to a small set of buildings. Moving to a new building can place you in a zone, thereby causing you to get a new address. A machine resuming from sleep mode is also very likely to be slow. Mitigations Sometimes, but not always, clearing the arp cache on an effected machine will allow it to work normally again. As already mentioned, releasing/renewing a local machine's IP address can fix that machine, but it's not guaranteed. Pinging the default gateway can also sometimes help with a slow machine. What seems to help most to mitigate the issue is clearing the arp cache on our core layer-3 switch. This switch is used for our dhcp system as the default gateway on all vlans, and it handles inter-vlan routing. The model is a 3Com 4900SX. To try to mitigate the issue, we have the cache timeout set on the switch all the way down to the lowest possible time, but it hasn't helped. I also put together a script that runs every few minutes to automatically connect to the switch and reset the cache. Unfortunately, this does not always work, and can even cause some machines to end up in the slow state for a short time (though these seem to correct themselves after a few minutes). We currently have a scheduled job that runs every 10 minutes to force the core switch to clear it's ARP cache, but this is far from perfect or desirable. Reproduction We now have a test machine that we can force into the slow state at will. It is connected to a switch with ports set up for each of our vlans. We make the machine slow by connecting to different vlans, and after a new connection or two it will be slow. It's also worth noting in this section that this has happened before at the start of prior terms, but in the past the problem has gone away on it's own after a few days. It solved itself before we had a chance to do much diagnostic work... hence why we've allowed it to drag so long into the term this time 'round; the expectation was this would be a short-lived situation. Other Factors It's worth mentioning that we have had about half a dozen switches just outright fail over the last year. These are mainly 2003/2004-era 3Coms (mostly 4200's) that were all put in at about the same time. They should still be covered under warranty, buy HP has made getting service somewhat difficult. Mostly in power supplies that have failed, but in a couple cases we have used a power supply from a switch with a failed mainboard to bring a switch with a failed power supply back to life. We do have UPS devices on all but three of four switches now, but that was not the case when I started two and a half years ago. Severe budget constraints (we were on the Dept. of Ed's financially challenged institutions list a couple years back) have forced me to look to the likes of Netgear and TrendNet for replacements, but so far these low-end models seem to be holding their own. It's also worth mentioning that the big change on our network this summer was migrating from a single cross-campus wireless SSID to the zoned approach mentioned earlier. I don't think this is the source of the issue, as like I've said: we've seen this before. However, it's possible this is exacerbating the issue, and may be much of the reason it's been so hard to isolate. Diagnosis At first it seemed clear to us, given the timing and persistent nature of the problem, that the source of the issue was an infected (or malicious) student machine doing ARP cache poisoning. However, repeated attempts to isolate the source have failed. Those attempts include numerous wireshark packet traces, and even taking entire buildings offline for brief periods. We have not been able even to find a smoking gun bad ARP entry. My current best guess is an overloaded or failing core switch, but I'm not sure on how to test for this, and the cost of replacing it blindly is steep. Again, any ideas appreciated.

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  • How to read and write UTF-8 to disk on the Android?

    - by Rob Kent
    I cannot read and write extended characters (French accented characters, for example) to a text file using the standard InputStreamReader methods shown in the Android API examples. When I read back the file using: InputStreamReader tmp = new InputStreamReader(in); BufferedReader reader = new BufferedReader(tmp); String str; while ((str = reader.readLine()) != null) { ... the string read is truncated at the extended characters instead of at the end-of-line. The second half of the string then comes on the next line. I'm assuming that I need to persist my data as UTF-8 but I cannot find any examples of that, and I'm new to Java. Can anyone provide me with an example or a link to relevant documentation?

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  • how do you get qTip to have proper width when loading content via ajax

    - by ooo
    i have an asp.net mvc site and here is a dynamic tooltip using qTip Here is my code: $('a.showNutritionInfo').each(function() { $(this).qtip({ content: { text: '<img src="../../images/ajax-loader1.gif" alt="" />', style: { width: 450 }, url: '/Tracker/NutritionInfo/' + $(this).attr('id'), method: 'get' } }); }); this works perfectly EXCEPT the width attribute listed above is ignored. No matter what i put in that width attribute, i get the same size width tooltip which is about half of the width that i need. the height is perfectly fine. any ideas? is this a bug in the product ?

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  • Can I remove a RAR file's (known) password without recompressing the archive?

    - by Abluescarab
    Long title. Anyway, I haven't been able to find an answer to this question. I know the password to the RAR file, I locked it myself, but now all I want to do is remove the password because it's too much of a pain in the butt to type it in every time. Is there a way to do this in WinRAR or an equivalent program? The only thing I knew to do was to extract it, then create a new RAR without the password. It's not a life-or-death issue, but it would be nice to know. Thanks for your time! EDIT: I just saw a bunch of related questions that appear to ask the same thing. The only solution I saw was using a DOS command to yadda yadda yadda. Here it is: How to remove password protection from compressed files Is there an easier way? Thanks again!

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  • VIsual Studio 2010 Web Performance Test / Load tests / Coded UI Tests. ANYONE REALLY USE THESE?

    - by punkouter
    I can find some articles on how to use them but I can't seem to find anywhere peoples impression of them using them in real projects. I have been trying to figure out how to use them and Ive had alot of problems.. Can someone out there who uses these tools on the job give me thier impression? Are there better alternate tools available? Using these really just a waste of time ? With Coded UI Tests I see how they are good for basic javascript checking but its so basic of a example I don't think it is worth it. With web tests I like how they work but when I activate code coverage/ASP.NET profiling it doesnt work half the time.

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  • Best Practice: Migrating Email Boxes (maildir format)

    - by GruffTech
    So here's the situation. I've got about 20,000 maildir email accounts chewing up a several hundred GB of space on our email server. Maildir by nature keeps thousands of tiny a** little files, instead of one .mbox file or the like... So i need to migrate all of these several millions of files from one server to the other, for both space and life-cycle reasons. the conventional methods i would use all work just fine. rsync is the option that comes immediately to mind, however i wanted to see if there are any other "better" options out there. Rsync not handling multi-threaded transfers in this situation sucks because it never actually gets up to speed and saturates my network connection, because of this the transfer from one server to another will take hours beyond hours, when it shouldn't really take more then one or two. I know this is highly opinionated and subjective and will therefore be marked community wiki.

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  • subversion 1.6.x losing changes on check-in

    - by Bernard
    I'm trying to figure out if this is a known issue with SVN 1.6.x Developer A modifies a file and commits it. Developer B modifies the same file. Tries to commit it and gets told local copy out of date so does an update and then a commit. However the changes from Developer A are lost so the resulting file only contains the version that Developer B checked in. We can see this in the logs. It seems to happen when the same file is modified but in different places. Anyone else experienced this? We've had it happen 4 or 5 times in the past few weeks and we've lost a half day or so each time trying to figure out what's been lost, etc. We're starting to lose confidence in SVN. Should we be thinking of moving to GIT or Mecurial? Would that sort out this problem?

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  • Secondary thread causes startup delay

    - by JK
    In my didFinishLaunchingWithOptions method I spawn a thread to perform some maintenance on my core data store. However, this increases the startup time by half a second. The startup view is a tableview which draws its content from the same store. If I let the thread sleep for a second, the startup time improves drastically. I would like to understand why the second thread is blocking/delaying the main thread. Is it because both are trying to access the store (The second thread has its own store coordinator and context) or another reason (e.g. dont spawn threads in didFinishLaunching)?

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  • How to add a layer to a menuitem image

    - by alexander
    I have a menuitem with an image. I want to add half-transparent layer to that image. private void menuItem1_Paint(object sender, PaintEventArgs e) { using (SolidBrush brush = new SolidBrush(Color.FromArgb(128, SystemColors.ActiveCaption))) { e.Graphics.FillRectangle(brush, e.ClipRectangle); } } My problem is = I don't know clientrectangle of that image. e.ClipRectangle - it fills whole menuitem. I want to fill only image. How ? Is there another way, maybe ?

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  • How to programmatically deactivate the AirPort?

    - by mystify
    I want to make a small utility to programmatically deactivate the AirPort of my mac. I have networking problems which couldnt be resolved by expensive experts. I need to deactivate and reactivate the mac AirPort once every half hour. So a little utility which does that automatically would be great. I think I wouldn't need an UI for this either. Just the most simple possible kind of application to automatically stop and start the AirPort. Maybe even apple automator code?

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  • Cisco NAC: help with enabling FTP or moving update files

    - by kyoung
    Hi, So this is a LINUX question, and a Cisco NAC question. I'm trying to update our server from 4.1 to 4.7, and i need to move some tarball files to the NAC. the NAC Appliance runs some strange stripped down version of Fedora Core 4 copying the upgrade: The instructions say to FTP the file to the NAC appliance, however whenever i use WinSCP with root credentials, i get a notice informing me the connection was actively refused. I can't for the life of me find any .conf files that sound like winners, so I don't know how to change the settings, however the ftp command does seem to work. what exactly should I do here?

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  • NetNamedPipe: varying response time when communication is idling

    - by Sven Künzler
    I have two WCF apps communicating one-way over named pipes. All is nice, except for one thing: Normally, the request/response cycle takes zero (marginal) time. However, if there was a time span of, say, half a minute without any communication, the request/response increases up to ~300-500ms. I looked around the net and I got the idea of using a heart beat/ping mechanism to keep the communication channel busy. Using trial and error I found that when doing a request each 10 seconds, the response times stay low. Starting at around 15s intervals, the "hiccup" response times begin to appear. Now I'm wondering where this phenomenon is originating from. I tried setting alle conceivable timeouts on both sides to 1 minute, but that did not help. Can anybody explain what's going on there?

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  • best IDE for ruby on rails

    - by Sanjay
    Having moved from java to ruby, I am struggling to find a good IDE for ruby. I used eclipse on java, so I tried Aptana Studio (previously Radrails), but its not even half as good. Currently I am trying out Netbeans for Ruby. Please suggest me the best RoR IDE out there. I believe TextMate is universally accepted as the best editor on Mac OS X. I am looking for windows. So far it seems netbeans and e-texteditor are worth a try.

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  • TCP 3 way handshake

    - by Tom
    Hi, i'm just observing what NMAP is doing for the 3 ports it reports are open. I understand what a half-scan attack is, but what's happening doesnt make sense. NMAP is reporting ports 139 are 445 are open..... all fine. But when i look at the control bits, NMAP never sends RST once it has found out the port is open, It does this for port 135- but not 139 and 445. This is what happens: (I HAVE OMITTED THE victim's replies) Sends a 2 (SYN) Sends a 16 (ACK) Sends a 24 (ACK + PST) Sends a 16 (ACK) Sends a 17 (ACK + FIN) I dont get why NMAP doesnt 'RST' ports 139 and 445??

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  • iPhone 3G backup encryption? I've never entered a password?

    - by Lewis
    I can't unclick or access my backup iPhone encrypted file. For the life of me I can not remember ever entering a password for the encrypted iPhone backups. I've tried every password I've used or use and nothing is working. I'm not getting anywhere with long searches online. Can anyone here help? iPhone 3.1.2 iTunes 9.1.1 Mac OSX 10.5.8 Please help, how do I get my iPhone backed up from my 'locked' file I've never locked?

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  • centralizing background image, using css

    - by Jean
    Hello, I want to centralize a background image. There is no div used, this is the css style body{ background-position:center; background-image:url(../images/images2.jpg) no-repeat; } The above CSS tiles all over and does centralize it, but half the image is not seen, it just kind of moves up. What I want to do is centralize the image. Could I adopt the image to view even on a 21". Appreciate help. Thanks Jean

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  • Best Tools for Software Maintenance Engineering

    - by Pev
    Yes, the dreaded 'M' word. You've got a workstation, source control and half a million lines of source code that you didn't write. The documentation was out of date the moment that it was approved and published. The original developers are LTAO, at the next project/startup/loony bin and not answering email. What are you going to do? {favourite editor} and Grep will get you started on your spelunking through the gnarling guts of the code base but what other tools should be in the maintenance engineers toolbox? To start the ball-rolling; I don't think I could live without source-insight for C/C++ spelunking. (DISCLAIMER: I don't work for 'em).

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  • Can I write functors using a private nested struct?

    - by Kristo
    Given this class: class C { private: struct Foo { int key1, key2, value; }; std::vector<Foo> fooList; }; The idea here is that fooList can be indexed by either key1 or key2 of the Foo struct. I'm trying to write functors to pass to std::find so I can look up items in fooList by each key. But I can't get them to compile because Foo is private within the class (it's not part of C's interface). Is there a way to do this without exposing Foo to the rest of the world? (note: I've got to run to a meeting. I'll be able to post more sample code in about a half hour.)

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  • How do I crash the App Pool?

    - by willem
    Our ASP.NET 2 web application handles exceptions very elegantly. We catch exceptions in Global ASAX in Application_Error. From there we log the exception and we show a friendly message to the user. However, this morning we deployed the latest version of our site. It ran ok for half an hour, but then the App Pool crashed. The site did not come back up until we restored the previous release. How can I make the app pool crash and skip the normal exception handler? I'm trying to replicate this problem, but with no luck so far. Update: we found the solution. One of our pages was screenscraping another page. But the URL was configured incorrectly and the page ended up screenscraping itself infinitely, thus causing a stack overflow exception.

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  • Backlight dimming don't work

    - by Mathias
    My Packard Bell EasyNote TS11HR notebook does not have an option for dimming the display backlight. At night, my eyes begin to hurt because of the strong light from the screen. My laptop is 2-3 months old and I am sure it has worked before. When I click on the battery icon in the notification area, it says in my language (Danish): "the setting for light does possibly reduce the life of the battery". However, I cannot dim the backlight. I have tried downloading programs for dimming the screen but they only make the screen darker, instead of dimming the backlight. I have tried updating my drivers and looking in the BIOS for a setting. I also plan to use an Ubuntu LiveCD to try controlling it. As of now though, the backlight is locked at maximum. Any ideas?

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  • I'm using the jQuery .scroll() function, why can't I override its effects with another function?

    - by Jason Rhodes
    I'm using the jQuery .scroll() function to make a certain element fade to 0.2 opacity. Since there is no native "scrollstop" indicator, I decided to make the element fade back to 1.0 opacity on hover. However, it doesn't work. Here's my code: $(document).ready(function() { $(window).scroll(function() { $("#navlist").animate({ opacity: 0.2 }, 2000); }); $("#navlist").hover( function() { $(this).animate({ opacity: 1 }, 500); }, function() { $(this).animate({ opacity: 1 }, 500); // just to be safe? } ); }); When I scroll, the #navlist element fades, but when you hover over it nothing happens. But if you refresh the page when you're half way down, the element automatically fades as soon as you refresh, before I've scrolled, and if you try to hover to fade it back in, nothing happens. Any thoughts?

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  • OpenGL and layouts

    - by Hnefi
    I'm using OpenGL to render a game view in my android application. The game is turn based and I wish to add some buttons to the interface. I'd prefer to use standard Android widgets, structured in an XML-generated layout (or, if I have to, a hardcoded layout) and put the OpenGL view in its own window as part of that layout. So in regards to this, I have 3 questions: 1: Is such a thing possible? I've done a few half-hearted tries, but have had no luck so far. 2: Is such a thing advisable? Does it carry a significant performance penalty, for example, over using OpenGL-based homebrew widgetry? 3: Is it possible to pass particular arguments to instances created in XML layouts? For example, my current OpenGL view has three arguments in its constructor; is it somehow possible for me to invoke that particular constructor with particular parameters when it's part of a layout?

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  • what to use instead of laptop-mode?

    - by playcat
    hello, i have ubuntu 10.10 64bit on hp 6735s (turion processor). it overheats, and i'm forced to use turion power control in order to keep core temperature to a reasonable level. one more measure that i use is putting my processors to conservative mode. that way, i'm perfectly happy with its performance, and heat is where it should be. however, after my latest upgrade, something happened - cores are back to ondemand by default, and i'm not sure if turionpowercontrol is working any more (ps axu | grep urion shows no process). in addition, i read somewhere that laptop-mode uses hdd spindown for preserving data/energy, and that hdds have only a limited amount of those spindowns, so laptop-mode usage can actually shorten the life of my hdd. i'm wondering if there is a good way to set my cores to automatically go to conservative mode? also, what's the good way to see what is the voltage my cores use? on windows i use cpuz tools. thx and sorry for the long explanation.

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  • Crystal Reports - Facilitating front/back printing

    - by hamlin11
    I have a crystal report that is designed to spit out a bunch of reports. Each report is 2 to 7 pages in length. We would like to print on the front and back of pages. However, if we did this now... approximately half of the following reports would print on the back of the last past of the preceding report. Is there a good method for detecting whether an extra page break should be inserted, and if so, actually inserting it, so that when we print the 150 pages front/back that now one piece of paper actually holds data from separate reports? Thanks

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