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• Batch File input validation - Make sure user entered an integer

  - by B2Ben

  I'm experimenting with a DOS batch file to perform a simple operation which requires the user to enter a non-negative integer. I'm using simple batch-file techniques to get user input: @ECHO OFF SET /P UserInput=Please Enter a Number: The user can enter any text they want here, so I would like to add some routine to make sure what the user entered was a valid number. That is... they entered at least one character, and every character is a number from 0 to 9. I'd like something I can feed the UserInput into. At the end of the routine would be like an if/then that would run different statements based on whether or not it was actually a valid number. I've experimented with loops and substrings and such, but my knowledge and understanding is still slim... so any help would be appreciated. I could build an executable, and I know there are nicer ways to do things than batch files, but at least for this task I'm trying to keep it simple by using a batch file.

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• Dns.GetHostEntry returns multiple IP addresses

  - by spender

  This question probably highlights a lack of understanding of networking principals on my part, rather than a programming issue. I'm doing a lookup on a hostname using Dns.GetHostEntry This returns an IPHostEntry to me, which has an AddressList property which is an array of IPAddress. I always thought there is a 1 to 1 mapping between hostname and IP, but I'm finding that in some cases I get back several IPAddress(es) for the same host. This is a surprise to me. Which part of domain name resolution do I not understand?

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• Why does MSBuild fail from the command line where VS2008 succeeds?

  - by sundeep

  I have an ASP.NET solution that builds just fine from within VS2008. However , it fails when i do this : MSBUILD.exe c:\path-to-sln It fails with a CS0006 error ("Metadata file 'dll_name' could not be found"). It also fails when I try with a .csproj of a project within the solution. What is VS2008 doing that MSBuild is missing ? It is my understanding that VS knows about inter assembly dependencies that MSBuild cant. Is there any way I can inform MSBuild of these? (I need MSBuild to work from the command line because I am calling it from an MSBuild-Task from within CruiseControl.Net.) Thanks in Advance. :3) (I have looked at http://stackoverflow.com/questions/280559/how-to-get-cmd-line-build-command-for-vs-solution , but still dont get it)

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• The advantages and disadvantages of using ORM

  - by JHarley1

  Good Morning, I would like to discuss today the advantages and disadvantages of using ORM (such as ADO.NET). Advantages: Speeds-up Development - eliminates the need for repetitive SQL code. Reduces Development Time. Reduces Development Costs. Overcomes vendor specific SQL differences - the ORM knows how to write vendor specific SQL so you don't have to. Disadvantages: Loss in developer productivity whilst they learn to program with ORM. Developers loose understanding of what the code is actually doing - the developer is more in control using SQL. ORM has a tendency to be slow. ORM fail to compete against SQL queries for complex queries. In summary, I believe that the disadvantages of using an ORM (mainly the reduced time taken to perform repetitive tasks) is far outweighed by the disadvantages of ORM e.g. its difficulty to get to grips with. Can people point out were I am going wrong and suggest any further advantages/disadvantages. Many Thanks, J

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• accessing $_SESSION when using file_get_contents in PHP

  - by hairdresser-101

  I am basic - intermediate developer using php and am a little stumped as to what I have found. I need some help in understanding how to alleviate this issue: I have a page called send.email.php which sends an email - pretty simple stuff - I pass an order id, it creates job request and sends it out. This works fine when used in the context I developed it (Use javascript to make an AJAX call to the URL and pass the order_id as a query parameter) I am now trying to reuse the exact same page in another application however I am calling it using php file_get_contents($base_url.'admin/send.email.php?order_id='.$order_id). When I call the page this way, the $_SESSION array is empty isempty() = 1. Is this because I am initiating a new session using file_get_contents and the values I stored in the $_SESSION on login are not available to me within there? Any help? Thanks

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• Computing orientation of a square and displaying an object with the same orientation

  - by Robin

  Hi, I wrote an application which detects a square within an image. To give you a good understanding of how such an image containing such a square, in this case a marker, could look like: What I get, after the detection, are the coordinates of the four corners of my marker. Now I don't know how to display an object on my marker. The object should have the same rotation/angle/direction as the marker. Are there any papers on how to achieve that, any algorithms that I can use that proofed to be pretty solid/working? It doesn't need to be a working solution, it could be a simple description on how to achieve that or something similar. If you point me at a library or something, it should work under linux, windows is not needed but would be great in case I need to port the application at some point. I already looked at the ARToolkit but they you camera parameter files and more complex matrices while I only got the four corner points and a single image instead of a whole video / camera stream.

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• help converting sql to linq expression with count

  - by Philip

  I am trying to convert the following SQL into a LINQ expression SELECT COUNT(ID) AS Count, MyCode FROM dbo.Archive WHERE DateSent=@DateStartMonth AND DateSent<=@DateEndMonth GROUP BY MyCode and I have been trying to follow this webpage as an example http://stackoverflow.com/questions/606124/converting-sql-containing-top-count-group-and-order-to-linq-2-entities I got this so far but I am stuck on understanding the new part var res=(from p in db.Archives where (p.DateSent>= dateStartMonth) && (p.DateSent< dateToday) group p by p.MyCode into g select new { ??????MyCode = g.something?, MonthlyCount= g.Count() }); Thanks in advance for helping greatly appreciated Philip

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• MIT vs. BSD vs. Dual License

  - by ryanve

  My understanding is that: MIT-licensed projects can be used/redistributed in BSD-licensed projects. BSD-licensed projects can be used/redistributed in MIT-licensed projects. The MIT and the BSD 2-clause licenses are essentially identical. BSD 3-clause = BSD 2-clause + the "no endorsement" clause Issuing a dual license allows users to choose from those licenses—not be bound to both. If all of the above is correct, then what is the point of using a dual MIT/BSD license? Even if the BSD refers to the 3-clause version, then can't a user legally choose to only abide by the MIT license? It seems that if you really want the "no endorsement" clause to apply then you have to license it as just BSD (not dual). If you don't care about the "no endorsement" clause, then MIT alone is sufficient and MIT/BSD is redundant. Similarly, since the MIT and BSD licenses are both "GPL-compatible" and can be redistributed in GPL-licensed projects, then dual licensing MIT/GPL also seems redundant.

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• Building Visual studio like application, need inputs..

  - by akjoshi

  Hi, I am working on a Visual studio like application i.e. hava a tolbox, an editor and property grid similar to VS. ser can drag and drop the controls(custom and third party) to the editor window and perform operations like resize, move, align, group etc.; Properties of that control needs to be displayed in property grid and user can update them from there. As per my current understanding I will have to extend the Canvas to create my own editor and and Interface for controls which it supports; Each supported control will have to implemnt this interface so that it can be placed in our editor. Something similar to this - http://www.codeproject.com/KB/WPF/WPFDiagramDesigner_Part4.aspx Looking forward for any kind of help, comment or links.

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• Linux bash: when to use egrep instead of grep?

  - by Michael Mao

  Hi all : I am preparing for a Linux terminal assessment now, I tried to Google and found most resources are referring to the basic "grep" rather than the more powerful "egrep" -- well, that is at least what the professor said in lecture. I am always working with small samples so performance tuning is a thing too far away. So basically I'd like to know are there any areas where I must switch to egrep to do it in a better way? Is it safe to work with basic "grep" as for now? will there be potential risks? Sorry about my limited knowledge on Linux shell commands, the man page looks like a maze to me and honestly I haven't put much time in understanding all the features both command provide.

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• Base class for windows service

  - by user187020

  My new project has a design in which there are number windows services for performing different tasks. I have been given a task to create base class from which all of the windows service will inherit. This base class will perform common functions like creating instances of other windows services by iterating through the config file (may be like Activator.CreateInstance), do event logging on onStart, onStop etc. and may contain some more functionality. Before I start developing stuff, wondering if there is any pattern already in place or someone has good understanding of how to implement this kind of functionality. Any help appreciated.

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• SSRS 2008 - Textbox RTF

  - by Iceman

  Hello, We have rtf text stored in our database that looks like the following: {\rtf1\ansi\deff0{\fonttbl{\f0\fnil\fcharset0 MS Sans Serif;}{\f1\fnil MS Sans Serif;}} {\colortbl ;\red0\green0\blue0;} \viewkind4\uc1\pard\cf1\lang1033\f0\fs22 Some Text Here \f1 \par } It is my understanding that SSRS 2008 should be able to properly display this on a report. Has anyone been able to have this display correctly? Robert Bruckner's Advanced Reporting Services Blog A new feature of SSRS: Leverage the enhanced Textbox (aka "RichText") to define mixed formatting within the same textbox. In addition, HTML strings of text can be imported into the report from a database or other source. Any help is greatly appreciated.

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• Good Economics book for developers

  - by Rocket Surgeon

  Joel mentions in several of his blog posts that it is very important for a developer/software entrepreneur to have solid understanding of Economics. Yet the Fog Creek MBA book reading list does not include any Economics books. Is there any good material that people can recommend? Obviously, I am not as concerned about mathematical treatise as foundations and basic principles. For example, I was able to find a very good high-level read on Macroeconomics: Concise Guide to Macroeconomics but I am yet to find anything similar on Microeconomics. Any suggestions and reading pointers would be highly appreciated.

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• How does delete deal with pointer constness?

  - by aJ

  I was reading this question Deleting a const pointer and wanted to know more about delete behavior. Now, as per my understanding: delete expression works in two steps: invoke destructor then releases the memory (often with a call to free()) by calling operator delete. operator delete accepts a void*. As part of a test program I overloaded operator delete and found that operator delete doesn't accept const pointer. Since operator delete does not accept const pointer and delete internally calls operator delete, how does Deleting a const pointer work ? Does delete uses const_cast internally?

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• Why is thread local storage so slow?

  - by dsimcha

  I'm working on a custom mark-release style memory allocator for the D programming language that works by allocating from thread-local regions. It seems that the thread local storage bottleneck is causing a huge (~50%) slowdown in allocating memory from these regions compared to an otherwise identical single threaded version of the code, even after designing my code to have only one TLS lookup per allocation/deallocation. This is based on allocating/freeing memory a large number of times in a loop, and I'm trying to figure out if it's an artifact of my benchmarking method. My understanding is that thread local storage should basically just involve accessing something through an extra layer of indirection, similar to accessing a variable via a pointer. Is this incorrect? How much overhead does thread-local storage typically have? Note: Although I mention D, I'm also interested in general answers that aren't specific to D, since D's implementation of thread-local storage will likely improve if it is slower than the best implementations.

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• BFS traversal of directed graph from a given node

  - by p1

  Hi, My understanding of basic BFS traversal for a graph is: BFS { Start from any node . Add it to que. Add it to visited array While(que is not empty) { remove head from queue. Print node; add all unvisited direct subchilds to que; mark them as visited } } However, if we have to traverse a DIRECTED graph from a given node and not all nodes are accessible from the given node [directly or indirectly] how do we use BFS for the same. Can you please explain in this graph as well: a= b = d = e = d a= c = d Here if the starting node is b , we never print a and c. Am I missing something in the algorithm. P.S: I used "HashMap adj = new HashMap();" to create the adjacencey list to store graph Any pointers are greatly appreciated. Thanks.

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• free() on stack memory

  - by vidicon

  I'm supporting some c code on Solaris, and I've seen something weird at least I think it is: char new_login[64]; ... strcpy(new_login, (char *)login); ... free(new_login); My understanding is that since the variable is a local array the memory comes from the stack and does not need to be freed, and moreover since no malloc/calloc/realloc was used the behaviour is undefined. This is a real-time system so I think it is a waste of cycles. Am I missing something obvious?

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• setDelegate:self, how does it work?

  - by fuzzygoat

  I have a query regarding how delegates work. My understanding was that delegates take responsibility for doing certain tasks on behalf of another object. locationManager = [[CLLocationManager alloc] init]; [locationManager setDelegate:self]; [locationManager setDistanceFilter:kCLDistanceFilterNone]; [locationManager setDesiredAccuracy:kCLLocationAccuracyBest]; [locationManager startUpdatingLocation]; Am I right in thinking that in the example code above that the instance of CLLocationManager is created on a new thread so that it can get on with trying to find the location information it needs. When it completes its task (or encounters an error) it calls-back using the appropriate methods located in self e.g. locationManager:didUpdateToLocation:fromLocation: Essentially locationManager sends messages to self (which conforms to the correct delegate protocol) when things happen cheers gary

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• How to implement a graph-structured stack?

  - by Emil

  Ok, so I would like to make a GLR parser generator. I know there exist such programs better than what I will probably make, but I am doing this for fun/learning so that's not important. I have been reading about GLR parsing and I think I have a decent high level understanding of it now. But now it's time to get down to business. The graph-structured stack (GSS) is the key data structure for use in GLR parsers. Conceptually I know how GSS works, but none of the sources I looked at so far explain how to implement GSS. I don't even have an authoritative list of operations to support. Can someone point me to some good sample code/tutorial for GSS? Google didn't help so far. I hope this question is not too vague.

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• Why is ruby called a dsl?

  - by b_ayan

  Recently, when I tried to explain why Ruby is a DSL to an intern at my organisation, I was not able to articulate my reasonings to the effect I would like to. Maybe I do not understand the space well enough to teach the nuances. Redirecting him to Martin Fowler' article or the google ranked one InfoQ or other material has not helped much either. Can some explain why Ruby is a DSL with an example / parallel situation which is not voodoo stuff for someone who is fairly new to the world of code? Understanding the ideology might also help in elaborating the intricacies of the rails ecosystem?

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• fsutil hardlink doesn't work?

  - by Alix Axel

  I was looking for a way to create hard links under Windows and I found this page: http://technet.microsoft.com/en-us/library/cc788097.aspx To try it out, I created a file (1.txt) on the root of my C: drive with 100 lines of the following content: C:\1.txt (2.598 bytes): test test test test test Then I open the command prompt and type: fsutil hardlink create C:\2.txt C:\1.txt Success, 2.txt was created but when I go to see it's size it has exactly 2.598 bytes and also noticed some strange behaviours (as far as my understanding of hard links goes): If I delete 2.txt (the hard linked file) 1.txt is not deleted, and vice-versa. If I open 2.txt after I delete 1.txt (the original file) the content is still the same. How does the fsutil hardlink create command differs from the copy command? And how can I create a true hard link under Windows? I'm using Windows XP SP 3, and my file system is NTFS.

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• What are Windows code pages?

  - by Mike D

  I'm trying to gain a basic understanding of what is meant by a Windows code page. I kind of get the feeling it's a translation between a given 8 bit value and some 'abstraction' for a given character graphic. I made the following experiment. I created a "" character literal with two versions of the letter u with an umlaut. One created using the ALT 129 (uses code page 437) value and one using the ALT 0252 (uses code page 1252) value. When I examined the literal both characters had the value 252. Is 252 the universal 8 bit abstraction for u with an umlaut? Is it the Unicode value? Aside from keyboard input are there any library routines or system calls that use code pages? For example is there a function to translate a string using a given code table (as above for the ALT 129 value)?

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• Concurrency Violation in NHibernate( c#) example

  - by vijaysylvester

  For quite some time , I was reading about the optimistic concurrency in NHibernate. If what i understood was correct then the below sample should hold good. Consider two transactions T1 and T2. When T1 and T2 are done simultaneously , the state(DB entries) gets updated with the values of the most latest update.(T1 or T2). Though it seems to be conceptually sound , how do i simulate this for the purpose of understanding and integration testing.? Can someone help me with a sample c# code.? Thanks , vijay

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• mysql, sqlite database source code

  - by Yang

  hi guys, i know implementing database is a huge topic, but i want to have a basic understanding of how database systems works (e.g. memory management, binary tree, transaction, sql parsing, multi-threading, partitions, etc) by investigating the source code of the database, since there are a few already proven very robust open source databases like mysql, sqlite and so on. however, the code are very complicated and i have no clue where to start. also i find that the old school database textbooks are only explaining the theory, not the implementation details. Can anyone suggest how should i get started and is there any books that emphasis on the technology and techniques of building dbms used in modern database industry? Thank in advance!

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• Boost interprocess cached pools

  - by porgarmingduod

  I'm trying to figure out if my reading of the docs for boost interprocess allocators is correct. When using cached_adaptive_pool to allocate memory: typedef cached_adaptive_pool<int, managed_shared_memory::segment_manager> pool_allocator_t; pool_allocator_t pool_allocator(segment.get_segment_manager()); // Allocate an integer in the shared memory segment pool_allocator_t::pointer pool_allocator.allocate_one(); My understanding is that with multiple processes one can allocate and deallocate freely: That is, if I have a cached pool allocator for integers in one process, then it can deallocate integers allocated by similar pools in other processes (provided, of course, that they are working on the same shared memory segment). It may be a stupid question, but working with multiple processes and shared memory is hard enough, so I'd like to know 100% whether I got the basics right.

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