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  • Why does gcc think that I am trying to make a function call in my template function signature?

    - by nieldw
    GCC seem to think that I am trying to make a function call in my template function signature. Can anyone please tell me what is wrong with the following? 227 template<class edgeDecor, class vertexDecor, bool dir> 228 vector<Vertex<edgeDecor,vertexDecor,dir>> Graph<edgeDecor,vertexDecor,dir>::vertices() 229 { 230 return V; 231 }; GCC is giving the following: graph.h:228: error: a function call cannot appear in a constant-expression graph.h:228: error: template argument 3 is invalid graph.h:228: error: template argument 1 is invalid graph.h:228: error: template argument 2 is invalid graph.h:229: error: expected unqualified-id before ‘{’ token Thanks a lot.

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  • How can I work around the fact that in C++, sin(3.14159265) is not 0?

    - by Adam Doyle
    In C++, const double Pi = 3.14159265; cout << sin(Pi); // displays: 3.58979e-009 it SHOULD display the number zero I understand this is because Pi is being approximated, but is there any way I can have a value of Pi hardcoded into my program that will return 0 for sin(Pi)? (a different constant maybe?) In case you're wondering what I'm trying to do: I'm converting polar to rectangular, and while there are some printf() tricks I can do to print it as "0.00", it still doesn't consistently return decent values (in some cases I get "-0.00") The lines that require sin and cosine are: x = r*sin(theta); y = r*cos(theta); BTW: My Rectangular - Polar is working fine... it's just the Polar - Rectangular Thanks! edit: I'm looking for a workaround so that I can print sin(some multiple of Pi) as a nice round number to the console (ideally without a thousand if-statements)

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  • If-elseif-else Logic Question

    - by Changeling
    I have a set of three values, call them x, y, and z. If value A happens to match only one in the set x, y, and z, then that means we have a proper match and we stop searching for a match, even if it is at y. It can match any one in that set. These values x, y, and z are non-constant so I cannot use a switch-case statement. How do I do this with an if-elseif-else statements without having to use GOTO. I am using C++ (no boost or any of that other fancy stuff). Now, I am trying to do this in code and it is racking my brain this morning (not enough coffee?)

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  • Embedding a querystring parameter in a hidden input with JSP results ing 500 error.

    - by dacracot
    I need a hidden input to contain the value passed by the querystring via a JSP's URL. The URL looks like... http://nowhere.com/myapp/blah.jsp?key=12345 The JSP looks like... <html> <body> <input id="key" type="hidden" value="<%=request.getParameter('key')%>" /> </body> </html> This causes a 500 error... SEVERE: Servlet.service() for servlet jsp threw exception org.apache.jasper.JasperException: Unable to compile class for JSP: An error occurred at line: 3 in the jsp file: /myapp/blah.jsp Invalid character constant 1: <html> 2: <body> 3: <input id="key" type="hidden" value="<%=request.getParameter('key')%>" /> 4: </body> 5: </html>

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  • runtime loading of ValidateAntiForgeryToken Salt value

    - by p.campbell
    Consider an ASP.NET MVC application using the Salt parameter in the [ValidateAntiForgeryToken] directive. The scenario is such that the app will be used by many customers. It's not terribly desirable to have the Salt known at compile time. The current strategy is to locate the Salt value in the web.config. [ValidateAntiForgeryToken(Salt = Config.AppSalt)] //Config.AppSalt is a static property that reads the web.config. This leads to a compile-time exception suggesting that the Salt must be a const at compile time. An attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type How can I modify the application to allow for a runtime loading of the Salt so that the app doesn't have to be re-salted and recompiled for each customer? Consider that the Salt won't change frequently, if at all, thereby removing the possibility of invalidating form

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  • How do I return an empty result set from a procedure using T-SQL?

    - by Kivin
    I'm interested in returning an empty result set from SQL Server stored procedures in certain events. The intended behaviour is that a L2SQL DataContext.SPName().SingleOrDefault() will result in CLR null value. I'm presently using the following solution, but I'm unsure whether it would be considered bad practice, a performance hazard (I could not find one by reading the execution plan), or if there is simply a better way: SELECT * FROM [dbo].[TableName] WHERE 0 = 1; The execution plan is a constant scan with a trivial cost associated with it. The reason I am asking this instead of simply not running any SELECTs is because I'm concerned previous SELECT @scalar or SELECT INTO statements could cause unintended result sets to be served back to L2SQL. Am I worrying over nothing?

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  • Thread vs ThreadPool - .Net 2.0

    - by NLV
    Hello I'm not able to understand the difference between Thread vs ThreadPool. Consider i've to manipulate 50,000 records using threads. In case of threads i need to either predefine no of threads or no of records per threads. Either of them has to be constant. In case of threadpool we dont need to set any of them theoretically. But practically we need to assign the number of records per thread, because the no of threads may grow extremely large if the input no of records is huge. Any insights on this?

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  • PHPDelicious - Fail to Connect to Delicious

    - by Meander365
    phpdelicious (http://www.phpdelicious.com/) is a wrapper class for pulling in your delicious bookmarks using php. But I can't get it to work. Here's my code - my index.php: <?php require('php-delicious.inc.php'); define('DELICIOUS_USER', 'my-user-name-here'); define('DELICIOUS_PASS', 'my-password-here'); $oDelicious = new PhpDelicious(DELICIOUS_USER, DELICIOUS_PASS); ?> <?php if ($aPosts = $oDelicious->GetAllPosts()) { foreach ($aPosts as $aPost) { echo '<a href="'.$aPost['url'].'">'.$aPost['desc'].'</a>'; echo $aPost['notes']; echo $aPost['updated']; } } else { echo $oDelicious->LastErrorString(); } ?> But I get this error : Notice: Use of undefined constant CACHE_PATH - assumed 'CACHE_PATH' in C:\wamp\www\testing\cache.inc.php on line 44 Connection to del.icio.us failed. Any ideas?

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  • long integer problem

    - by hopefulLLl
    hello friends,, m a beginner at c language.. m using turbo c ++ compiler 16 bit. nw the max answer obtained by me is aaround 32000.. nw if i want a number larger that that then i use long int.. if i execute the following programme.. #include <stdio.h> void main() { long int x; x=40000; printf("%d", x); } then i get error that constant value is long in function main().. kindly tell me how to get an answer more that 32000 by getting rid of this error! thnx..

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  • Decoding equivalent assembly code of C code...

    - by puffadder
    Hi All, Wanting to see the output of the compiler (in assembly) for some C code, I wrote a simple program in C and generated its assembly file using gcc. The code is this: #include <stdio.h> int main() { int i = 0; if ( i == 0 ) { printf("testing\n"); } return 0; } The generated assembly for it is here (only the main function): _main: pushl %ebpz movl %esp, %ebp subl $24, %esp andl $-16, %esp movl $0, %eax addl $15, %eax addl $15, %eax shrl $4, %eax sall $4, %eax movl %eax, -8(%ebp) movl -8(%ebp), %eax call __alloca call ___main movl $0, -4(%ebp) cmpl $0, -4(%ebp) jne L2 movl $LC0, (%esp) call _printf L2: movl $0, %eax leave ret I am at an absolute loss to correlate the C code and assembly code. All that the code has to do is store 0 in a register and compare it with a constant 0 and take suitable action. But what is going on in the assembly ? Thanks in advance.

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  • mmap() for large file I/O?

    - by Boatzart
    I'm creating a utility in C++ to be run on Linux which can convert videos to a proprietary format. The video frames are very large (up to 16 megapixels), and we need to be able to seek directly to exact frame numbers, so our file format uses libz to compress each frame individually, and append the compressed data onto a file. Once all frames are finished being written, a journal which includes meta data for each frame (including their file offsets and sizes) is written to the end of the file. I'm currently using ifstream and ofstream to do the file i/o, but I am looking to optimize as much as possible. I've heard that mmap() can increase performance in a lot of cases, and I'm wondering if mine is one of them. Our files will be in the tens to hundreds of gigabytes, and although writing will always be done sequentially, random access reads should be done in constant time. Any thoughts as to whether I should investigate this further, and if so does anyone have any tips for things to look out for? Thanks!

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  • lock file so that it cannot be deleted

    - by JoeCool
    I'm working with two independent c/c++ applications on Windows where one of them constantly updates an image on disk (from a webcam) and the other reads that image for processing. This works fine and dandy 99.99% of the time, but every once in a while the reader app is in the middle of reading the image when the writer deletes it to refresh it with a new one. The obvious solution to me seems to be to have the reader put some sort of a lock on the file so that the writer can see that it can't delete it and thus spin-lock on it until it can delete and update. Is there anyway to do this? Or is there another simple design pattern I can use to get the same sort of constant image refreshing between two programs? Thanks, -Robert

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  • How can i underline a text in JDK5, NOT JDK6

    - by Serkan Kasapbasi
    when i search internet i have found a way to underline font like this, Font f=jLabel1.getFont(); Map<TextAttribute,Object> map = new Hashtable<TextAttribute,Object>(); map.put(TextAttribute.UNDERLINE,TextAttribute.UNDERLINE_ON); f=f.deriveFont(map); jLabel1.setFont(f); it works well on jdk6, however it doesnt work on jdk5, and it doesnt warn about anything. first, how can i get same effect on jdk5? second, why is there a TextAttribute.UNDERLINE constant, if it doesnt work?

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  • maths: motion depending on time

    - by clamp
    hello, i have a mathematical problem: i have a function where the only parameter is the current time. the return should be a position which is used to place an object on a certain place. int position(int time) { int x = 0; //TODO implement x depending on time return x; } so basically the function is called every frame to put the object in motion. the motion should look like this (this is the actual question): a linear motion for time A, the object moves at constant speed no motion for time B, the object is stopped repeat at 1. thanks!

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  • Get a list of documents from Mongo DB

    - by Andrei Neagu
    Hello, I want to do something like this: List<int> fff = new List<int>(); fff.Add(1); fff.Add(2); fff.Add(5); Mongo m = new Mongo(); m.Connect(); var dataBase = m.GetDatabase("database"); var collection = dataBase.GetCollection("coll"); IMongoQuery queryable = collection.AsQueryable(); MongoQueryProvider prov = new MongoQueryProvider(collection); var query = new MongoQuery(prov); var ffppp = from p221 in query where fff.Contains((int)p221["oid"]) select p221; This throws this error : The method 'Contains' could not be converted into a constant. I saw that mongo has an operator $in. Does any one know how can I use it from c#? (http://www.mongodb.org/display/DOCS/Advanced+Queries) Thanks

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  • How do I inhibit "note C6311" in Microsoft C compiler?

    - by piCookie
    In this maximally clipped source example, the manifest constant FOOBAR is being redefined. This is deliberate, and there is extra code in the live case to make use of each definition. The pragma was added to get rid of a warning message, but then a note appeared, and I don't seem to find a way to get rid of the note. I've been able to modify this particular source to #undef between the #define, but I would like to know if there's a way to inhibit the note without requiring #undef, since there are multiple constants being handled the same way. #pragma warning( disable : 4005 ) // 'identifier' : macro redefinition #define FOOBAR FOO #define FOOBAR BAR The compiler banner and output are as follows Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8804 for 80x86 Copyright (C) Microsoft Corp 1984-1998. All rights reserved. message.c message.c(3) : note C6311: message.c(2) : see previous definition of 'FOOBAR'

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  • recursion tree and binary tree cost calculation

    - by Tony
    Hi all, I've got the following recursion: T(n) = T(n/3) + T(2n/3) + O(n) The height of the tree would be log3/2 of 2. Now the recursion tree for this recurrence is not a complete binary tree. It has missing nodes lower down. This makes sense to me, however I don't understand how the following small omega notation relates to the cost of all leaves in the tree. "... the total cost of all leaves would then be Theta (n^log3/2 of 2) which, since log3/2 of 2 is a constant strictly greater then 1, is small omega(n lg n)." Can someone please help me understand how the Theta(n^log3/2 of 2) becomes small omega(n lg n)?

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  • mod,prime -> inverse possible

    - by Piet
    Hi all. I was wondering if one can do the following: We have: X is a product of N-primes, thus I assume unique. C is a constant. We can assure that C is a number that is part of the N-primes or not. Whichever will work best. Thus: X mod C = Z We have Z and C and we know that X was a product of N-primes, where N is restricted lets say first 100 primes. Is there anyway we can get back X?

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  • Can I configure NUnit so that Debug.Fail doesn't show a message box when I run my tests?

    - by panamack
    I have this property: public SubjectStatus Status { get { return status; } set { if (Enum.IsDefined(typeof(SubjectStatus), value)) { status = value; } else { Debug.Fail("Error setting Subject.Status", "There is no SubjectStatus enum constant defined for that value."); return; } } } and this unit test [Test] public void StatusProperty_StatusChangedToValueWithoutEnumDefinition_StatusUnchanged() { Subject subject = new TestSubjectImp("1"); // assigned by casting from an int to a defined value subject.Status = (SubjectStatus)2; Assert.AreEqual(SubjectStatus.Completed, subject.Status); // assigned by casting from an int to an undefined value subject.Status = (SubjectStatus)100; // no change to previous value Assert.AreEqual(SubjectStatus.Completed, subject.Status); } Is there a way I can prevent Debug.Fail displaying a message box when I run my tests, but allow it to show me one when I debug my application?

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  • How can my CGI program access non-browseable files?

    - by Zerobu
    I was wondering if it was possible to read a text file that was located in a directory called "/home/user/files" I wanted to read it from my cgi-bin which is located in /home/user/cgi-bi/ Below is my code, #!/usr/bin/perl use strict; use CGI; #Virtual Directory #Steffan Harris eval { use constant PASSWORD => 'perl'; use constant UPLOAD_DIR => '/home/sharris2/files'; sub mapToFile { print chdir UPLOAD_DIR; } #This function will list all files in a directory. sub listDirectoryFiles { chdir UPLOAD_DIR; my @files = <*>; mapToFile; print<<LIST; <h2>Current Files</h2> <ul> LIST if(!$files[0]) { print" </ul>\n<em>No files in directory</em>"; } foreach(@files) { print" <li>$_</li>"; } print " </ul>\n"; } #This function generates a 404 Not Found error sub generate404 { print<<RESPONSE; Status: 404 Not Found Content-Type: text/html <html> <head><title>404 Not Found</title></head> <body> <p> <h1>404 - Not Found</h1> </p> The requested URL <b>$ENV{"HTTP_HOST"}$ENV{"REQUEST_URI"}</b> was not found on the server. </body> </html> RESPONSE exit; } #This function checks the path info to see if it matches a file in the UPLOAD_DIR directory, If it does not, then it returns a 404 error sub checkExsistence { if($ENV{"PATH_INFO"}) { chdir UPLOAD_DIR; my @files = <*>; if(!$files[0] and $ENV{"PATH_INFO"} eq "/") { return; } foreach(@files) { if($ENV{"PATH_INFO"} eq "/".$_ || $ENV{"PATH_INFO"} eq "/") { print "yes"; return; } } generate404; } } sub checkPassword { my ($password, $cgi); $cgi = new CGI; $password = $cgi->param('passwd'); unless($password eq PASSWORD) { print<<RESPONSE; Status: 200 OK Content-Type: text/html <html> <head> <title>Incorrect Password</title> </head> <body> <h1>Invalid password entered.</h1> <h3><a href="/~sharris2/cgi-bin/files/">Go Back</a></h3> </body> RESPONSE exit; } } sub upLoadFile { checkPassword; my ($uploadfile, $cgi); $cgi = new CGI; $uploadfile = $cgi->upload('uploadfile'); chdir UPLOAD_DIR; $uploadfile or die "Did not receive a file to upload"; open my $FILE, '>', UPLOAD_DIR."/$uploadfile" or die "$!"; while(<$uploadfile>) { print $FILE $_; } } #Start of main part of program my $cgi = new CGI; if(!$ENV{"PATH_INFO"}) { print $cgi->redirect('/~sharris2/cgi-bin/files/'); } checkExsistence; if($ENV{"REQUEST_METHOD"} eq "POST") { upLoadFile; } print <<"HEADERS"; Status: 200 OK Content-Type: text/html HEADERS print <<"HTML"; <html> <head> <title>Virtual Directory</title> </head> <body> HTML listDirectoryFiles; print<<HTML; <h2>Upload a new file</h2> <form method = "POST" enctype = "multipart/form-data" action = "/~sharris2/cgi-bin/files/" /> File:<input type = "file" name="uploadfile"/> <p>Password: <input type = "password" name ="passwd"/></p> <p><input type = "submit" value= "Submit File" /></p> </form> </body> </html> HTML };

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  • Vectorizing sums of different diagonals in a matrix

    - by reve_etrange
    I want to vectorize the following MATLAB code. I think it must be simple but I'm finding it confusing nevertheless. r = some constant less than m or n [m,n] = size(C); S = zeros(m-r,n-r); for i=1:m-r for j=1:n-r S(i,j) = sum(diag(C(i:i+r-1,j:j+r-1))); end end The code calculates a table of scores, S, for a dynamic programming algorithm, from another score table, C. The diagonal summing is to generate scores for individual pieces of the data used to generate C, for all possible pieces (of size r). Thanks in advance for any answers! Sorry if this one should be obvious...

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  • twitter gem not working in heroku ?

    - by Luc
    Hello, I'm working on a ruby app that updates a twitter account using 'twitter' gem. It's working fine locally (as usual :) ). But when I deploy it on heroku it seems the gem is not properly installed or something lile that as I got the following error: NameError: uninitialized constant Twitter::OAuth My code is very simple: oauth = Twitter::OAuth.new(consumer_token, consumer_secret) oauth.authorize_from_access(access_token, access_secret) client = Twitter::Base.new(oauth) client.update("Updating my status from twitter gem. GREAT!") Is there a problem with this particular gem ? Thanks a lot for your help. Luc

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  • How to get current compass reading android 2.1

    - by Brandon Delany
    How do I get the current compass reading in android 2.1? I know that I can initiate a listener and receive updates but I do not need constant updates I only need it to get the compass orientation when the user clicks a button. Also what is the most accurate way to get the compass orientation? Lastly, how do I send fake data to the android console. I know that you're supposed to use the terminal and send it commands but what are the commands I can't seem to find it on the Android website. Thank you

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  • Why doesn't this code using the ruby-mbox gem parse mbox files?

    - by cartoonfox
    I installed ruby-mbox by doing gem install ruby-mbox Running this: #!/usr/bin/ruby require 'rubygems' require 'mbox' m = IO.read('test.eml') puts m.size m = Mbox.new(m) puts m produces this: 71309505 /Library/Ruby/Gems/1.8/gems/ruby-mbox-0.0.2/lib/mbox/mbox.rb:45:in `initialize': uninitialized constant Mbox::StringIO (NameError) from r.rb:7:in `new' from r.rb:7 I have proved that "m" is assigned a string containing the contents of the file, just before Mbox.new(m) is called. It looks as though the Mbox::StringIO should have been defined by hasn't been. What's going wrong here? Ruby version: ruby 1.8.7 (2009-06-12 patchlevel 174) [universal-darwin10.0] (That's the default ruby installed on OS X 10.6.6)

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  • Any form autofill for 'Developers'?

    - by Majid
    Hi all, I have looked at some autofills for Firefox. But they are not designed with the developers' needs in mind. General internet surfers will need a tool to fill in many different forms with constant values for each form. Developers need exactly the opposite, when you want to test a part of your app you'll need to fill a single (or a couple of) forms many times with different (but valid and sensible) data. So, does such a thing exist? An autofill to fill form inputs based on perhaps a class name (email, password, address, url, ...)? I strongly feel if it doesn't exist someone should roll up their sleeves and make one! I for one will put in my share if some others want to team up. But right now, I am desperately in need of one if it exists

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