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  • What is the point of function pointers?

    - by gramm
    Hi, I have trouble seing the utility of the function pointers. I guess it may be useful in some cases (they exist, after all), but I can't think of a case where it's better or unavoidable to use a function pointer. Could you give some example of good use of function pointers (in C or C++)? Many thanks :)

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  • Hashing a python function to regenerate output when the function is modified

    - by Seth Johnson
    I have a python function that has a deterministic result. It takes a long time to run and generates a large output: def time_consuming_function(): # lots_of_computing_time to come up with the_result return the_result I modify time_consuming_function from time to time, but I would like to avoid having it run again while it's unchanged. [time_consuming_function only depends on functions that are immutable for the purposes considered here; i.e. it might have functions from Python libraries but not from other pieces of my code that I'd change.] The solution that suggests itself to me is to cache the output and also cache some "hash" of the function. If the hash changes, the function will have been modified, and we have to re-generate the output. Is this possible or ridiculous? Updated: based on the answers, it looks like what I want to do is to "memoize" time_consuming_function, except instead of (or in addition to) arguments passed into an invariant function, I want to account for a function that itself will change.

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  • A script that writes errors and should create a event-error

    - by helmich
    this if it works should check the internet connection if there is a connection it does nothing. if there isn't a connection it should write a error in a txtfile if that happend 5 times it should create a error but it doesn't I will show you the whole code that i have now and the piece of code that i want in a loop. I can't get it in the way i want. I want it to creat 1 Event-error after 5 times writing to the file. this is the whole code i will put the code i want in a loop under it strDirectory = "Z:\text2" strFile = "\foutmelding.txt" strText = "De connectie is verbroken" strWebsite = "www.helmichbeens.com" If PingSite(strWebsite) Then WScript.Quit 'Website is pingable - no further action required Set objFSO = CreateObject("Scripting.FileSystemObject") RecordSingleEvent Dim fout For fout = 1 To 5 : Do If fout = 5 Then Exit Do Set WshShell = WScript.CreateObject("WScript.Shell") Call WshShell.LogEvent(1, "Test Event") Loop While False : next '------------------------------------ 'Record a single event in a text file '------------------------------------ Sub RecordSingleEvent If Not objFSO.FolderExists(strDirectory) Then objFSO.CreateFolder(strDirectory) Set objTextFile = objFSO.OpenTextFile(strDirectory & strFile, 8, True) objTextFile.WriteLine(Now & strText) objTextFile.Close End sub '---------------- 'Ping my web site '---------------- Function PingSite( myWebsite ) Set objHTTP = CreateObject( "WinHttp.WinHttpRequest.5.1" ) objHTTP.Open "GET", "http://" & myWebsite & "/", False objHTTP.SetRequestHeader "User-Agent", "Mozilla/4.0 (compatible; MyApp 1.0; Windows NT 5.1)" On Error Resume Next objHTTP.Send PingSite = (objHTTP.Status = 200) On Error Goto 0 End Function '----------------------------------------------- 'Counts the number of lines inside the text file '----------------------------------------------- Function EventCount(fout) strData = objFSO.OpenTextFile(strDirectory & strFile,ForReading).ReadAll arrLines = Split(strData,vbCrLf) EventCount = UBound(arrLines) End Function This is the whole code, and it doesnt work correctly becaus it creats a event-log rightaway and it should do that after the script has written 5 times to the textfile here is the code that writes to a textfile Sub RecordSingleEvent If Not objFSO.FolderExists(strDirectory) Then objFSO.CreateFolder(strDirectory) Set objTextFile = objFSO.OpenTextFile(strDirectory & strFile, 8, True) objTextFile.WriteLine(Now & strText) objTextFile.Close End sub and here is the code but this part doesnt not work or atleast i think it is this part Dim fout For fout = 1 To 5 : Do If fout = 5 Then Exit Do Set WshShell = WScript.CreateObject("WScript.Shell") Call WshShell.LogEvent(1, "Test Event") Loop While False : next Function EventCount(fout) strData = objFSO.OpenTextFile(strDirectory & strFile,ForReading).ReadAll arrLines = Split(strData,vbCrLf) EventCount = UBound(arrLines) End Function this is the not working part and I don't know what to do anymore so can you please take a look at it tank you very much. btw: this code can be very usefull for a network administrator

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  • Query with UDF works in Access but gives Undefined function in expression (Err 3085) in Excel

    - by ronwest
    I have an Access table with a date/time field. I wanted to make a composite Key field out of the date/time field and 3 other text fields in the same format as the matching Key field in another database. So I concatenated the 3 text fields and wrote a User-Defined-Function in a Module to output the date field as a string in the format "YYYYMMDD". Public Function YYYYMMDD(dteDate As Date) As String YYYYMMDD = Format(dteDate, "YYYYMMDD") End Function I can then successfully run my queries in Access and it all works fine. But when I set up some DAO code in Excel and try to run the query that works fine within Access... db.Execute "qryMake_tblValsDailyAccount" ...Excel gives me the "Undefined function in expression. (Error 3085)" error. To me this is a bug in Excel and/or Access, because the (Excel) client shouldn't need to know anything about the internal calculations that normally take place perfectly in the (Access) server when in isolation. Excel should send the querydef (name with no parameters) to the server, let the server do its work then receive the answers. Why does it need to get involved with a function internal to the server? Does anyone know a way around this?

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  • Set the output of a function equal to a variable

    - by ryno
    How would i set the output of a custom php function to a variable? The function is: function getRandomColor1() { global $cols; $num_cols = count($cols); $rand = array_rand($cols); $rand_col = $cols[$rand]; echo $rand_col; unset($cols[$rand]); } How would i set getRandomColor1 equal to $RandomColor1? I need it to be a variable so I can use it in css like: #boxone1 { height: 150px; width: 150px; background: <?=$RandomColor1?>; float: left; } If its not possible to set it as a variable, how else could i put the output of the function into css?

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  • C++: How do I pass a function(without knowing its parameters) to another function?

    - by Ninja
    Hi all. I'm trying to create a function that will store and repeat another function given as a parameter for a specific amount of time or repeats given. But when you want to pass a function as a parameter you have to know all of its parameters before hand. How would I do if I wanted to pass the function as one parameter, and the parameters as another? void AddTimer(float time, int repeats, void (*func), params); // I know params has no type and that (*func) is missing parameters but it is just to show you what I mean Thanks in advance

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  • function in c language

    - by sandy101
    Hello, I am practice the function in c and come across to the program .... include int main() { float a=15.5; char ch ='C'; printit(a,ch); return 0; } printit(a,ch) { printf("%f\n%c",a,ch); } I want to know that why the above program compile and not give the error as i understood so for is ... 1) The function in c must be declared with the specific prototype (but this program does not contain the prototype ) 2)why the program give the output 'x'for the char variable 3)can the function in c are capable of accepting the value without being declared about type in parameters like what has done in the function declaration .... plz.... help

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  • create a model in create action from a class

    - by Pontek
    As a newbie to rails I can't find how to solve my issue ^^ I want to create a VideoPost from a form with a text field containing a video url (like youtube) I'm getting information on the video thanks to the gem https://github.com/thibaudgg/video_info And I want to save thoses information using a model of mine (VideoInformation). But I don't know how the create process should work. Thanks for any help ! I'm trying to create a VideoPost in VideoPostsController like this : def create video_info = VideoInfo.new(params[:video_url]) video_information = VideoInformation.create(video_info) #undefined method `stringify_keys' for #<Youtube:0x00000006a24120> if video_information.save @video_post = current_user.video_posts.build(video_information) end end My VideoPost model : # Table name: video_posts # # id :integer not null, primary key # user_id :integer # video_information_id :integer # created_at :datetime not null # updated_at :datetime not null My VideoInformation model (which got same attributes name than VideoInfo gem) : # Table name: video_informations # # id :integer not null, primary key # title :string(255) # description :text # keywords :text # duration :integer # video_url :string(255) # thumbnail_small :string(255) # thumbnail_large :string(255) # created_at :datetime not null # updated_at :datetime not null

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  • Start a thread using a method pointer

    - by Michael
    Hi ! I'm trying to develop a thread abstraction (POSIX thread and thread from the Windows API), and I would very much like it to be able to start them with a method pointer, and not a function pointer. What I would like to do is an abstraction of thread being a class with a pure virtual method "runThread", which would be implanted in the future threaded class. I don't know yet about the Windows thread, but to start a POSIX thread, you need a function pointer, and not a method pointer. And I can't manage to find a way to associate a method with an instance so it could work as a function. I probably just can't find the keywords (and I've been searching a lot), I think it's pretty much what Boost::Bind() does, so it must exist. Can you help me ?

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  • Invoking jQuery function without an element

    - by Sandman
    So, I use jQuery quite extensively and I am well aware of the "right" way to do the below, but there are times where I want to solve it in a more generic way. I'll explain. So, I may have a link, like this: <a href='menu' class='popup'>Show menu</a>. Now, I have a jQuery function that fires on click for all a.popup that takes the href-attribute and shows the <div id='menu'></div> item (in this case). It also handles URL's if it can't find a DOM item with that ID. No problem here. But, there are times when I don't have the same control over the coe where I can create a selectable target that way. Either because the code isn't created by me or because it is created through a chain of function that would all need a huge ovrhaul which I won't do. So, from time to time, I would like to have this code: <a href="javascript:popup('menu')">Show menu</a> This would be in a case where I can only submit the label and the HREF for a link. No class, no nothing. Problem here is that the function popup() has no idea about what element invoked it, and in most cases that's not a problem for me, since I only need to know where the mouse cursor was upon invokation. But in some cases, I use someone elses jQuery functions, like qTip or something else. so I still want to fire off qTip(); when clicking a link that runs this JS function, but what do I attach it to to make it show? I can't just runt $().qTip(); because that implies $(this) and "this" is undefined inside the function. So how do I do it? Any ideas?

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  • PHP callback function not being called

    - by Industrial
    Hi everyone, I've got the following code: function _callback_memcache_failure($host, $port) { print "memcache '$host:$port' failed"; } $this->memcache = new Memcache; $this->memcache->addServer('192.168.1.35', '11211', 0, 50, 10, TRUE, _callback_memcache_failure('192.168.1.35','11211')); The server is online and running (verified!), but the Failure callback function is being called at each connection. Why is that? Reference: PHP documentation: Memcache::addServer - failure_callback Allows the user to specify a callback function to run upon encountering an error. The callback is run before failover is attempted. The function takes two parameters, the hostname and port of the failed server .

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  • what is wrong with my create table SQL?

    - by George2
    Hello everyone, I am using SQL Server 2008 management studio to execute the following SQL statements, and here is the related error message from SQL Server management studio. Any ideas what is wrong? SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO Create TABLE [dbo].[BatchStatus]( [BatchID] [uniqueidentifier] NOT NULL CONSTRAINT [PK_BatchStatus_ID], [BatchStatus] [int] NULL, CONSTRAINT [PK_BatchStatus_ID] PRIMARY KEY CLUSTERED ( [BatchID] ASC )WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY] ) ON [PRIMARY] GO Msg 102, Level 15, State 1, Line 3 Incorrect syntax near ','. Msg 319, Level 15, State 1, Line 8 Incorrect syntax near the keyword 'with'. If this statement is a common table expression, an xmlnamespaces clause or a change tracking context clause, the previous statement must be terminated with a semicolon. thanks in advance, George

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  • jquery - using a function id in a different function

    - by andrew
    Hi, I have a function like that: function loadcategory(id) { jQuery("#categoryArea").load("ajax_post_category.php?catid="+id+""); } im getting id via link like that: <a href='javascript:loadcategory(".$row['catid'].");'> i would like to use function loadcategory(id)'s id in a different function. for example: function different() { jQuery("#different").load("ajax_post_category.php?catid="+loadcategory(id)+""); } as you can see i wanted to use +loadcategory(id)+, however i havent gotten any values. well, how can i get that value by jquery? i dont know, can anyone tell me the true way? regards

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  • Periods in Javascript function definition (function window.onload(){}) [closed]

    - by nemec
    Possible Duplicate: JavaScript Function Syntax Explanation: function object.myFunction(){..} I've seen some (legacy) javascript code recently that looks like: function window.onload(){ // some code } This doesn't look like valid javascript to me since you can't have a period in an identifier, but it seems to work in IE8. I assume it's the equivalent of: window.onload = function(){} I've tried the same code in Chrome and IE9 and both of them raise syntax exceptions, so am I correct in thinking that this "feature" of IE8 is some non-standard function definition that should be replaced? The code in question is only sent to IE browsers, so that's probably why I haven't run into this issue before.

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  • Trouble passing a template function as an argument to another function in C++

    - by Darel
    Source of the problem -Accelerated C++, problem 8-5 I've written a small program that examines lines of string input, and tallies the number of times a word appears on a given line. The following code accomplishes this: #include <map> #include <iostream> #include <string> #include <vector> #include <list> #include <cctype> #include <iterator> using std::vector; using std::string; using std::cin; using std::cout; using std::endl; using std::getline; using std::istream; using std::string; using std::list; using std::map; using std::isspace; using std::ostream_iterator; using std::allocator; inline void keep_window_open() { cin.clear(); cout << "Please enter EOF to exit\n"; char ch; cin >> ch; return; } template <class Out> void split(const string& s, Out os) { vector<string> ret; typedef string::size_type string_size; string_size i = 0; // invariant: we have processed characters `['original value of `i', `i)' while (i != s.size()) { // ignore leading blanks // invariant: characters in range `['original `i', current `i)' are all spaces while (i != s.size() && isspace(s[i])) ++i; // find end of next word string_size j = i; // invariant: none of the characters in range `['original `j', current `j)' is a space while (j != s.size() && !isspace(s[j])) ++j; // if we found some nonwhitespace characters if (i != j) { // copy from `s' starting at `i' and taking `j' `\-' `i' chars *os++ = (s.substr(i, j - i)); i = j; } } } // find all the lines that refer to each word in the input map<string, vector<int> > xref(istream& in) // works // now try to pass the template function as an argument to function - what do i put for templated type? //map<string, vector<int> > xref(istream& in, void find_words(vector<string, typedef Out) = split) #LINE 1# { string line; int line_number = 0; map<string, vector<int> > ret; // read the next line while (getline(in, line)) { ++line_number; // break the input line into words vector<string> words; // works // #LINE 2# split(line, back_inserter(words)); // #LINE 3# //find_words(line, back_inserter(words)); // #LINE 4# attempting to use find_words as an argument to function // remember that each word occurs on the current line for (vector<string>::const_iterator it = words.begin(); it != words.end(); ++it) ret[*it].push_back(line_number); } return ret; } int main() { cout << endl << "Enter lines of text, followed by EOF (^Z):" << endl; // call `xref' using `split' by default map<string, vector<int> > ret = xref(cin); // write the results for (map<string, vector<int> >::const_iterator it = ret.begin(); it != ret.end(); ++it) { // write the word cout << it->first << " occurs on line(s): "; // followed by one or more line numbers vector<int>::const_iterator line_it = it->second.begin(); cout << *line_it; // write the first line number ++line_it; // write the rest of the line numbers, if any while (line_it != it->second.end()) { cout << ", " << *line_it; ++line_it; } // write a new line to separate each word from the next cout << endl; } keep_window_open(); return 0; } As you can see, the split function is a template function to handle various types of output iterators as desired. My problem comes when I try to generalize the xref function by passing in the templated split function as an argument. I can't seem to get the type correct. So my question is, can you pass a template function to another function as an argument, and if so, do you have to declare all types before passing it? Or can the compiler infer the types from the way the templated function is used in the body? To demonstrate the errors I get, comment out the existing xref function header, and uncomment the alternate header I'm trying to get working (just below the following commment line.) Also comment the lines tagged LINE 2 and LINE 3 and uncomment LINE 4, which is attempting to use the argument find_words (which defaults to split.) Thanks for any feedback!

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  • SQL SERVER – Introduction to LEAD and LAG – Analytic Functions Introduced in SQL Server 2012

    - by pinaldave
    SQL Server 2012 introduces new analytical function LEAD() and LAG(). This functions accesses data from a subsequent row (for lead) and previous row (for lag) in the same result set without the use of a self-join . It will be very difficult to explain this in words so I will attempt small example to explain you this function. Instead of creating new table, I will be using AdventureWorks sample database as most of the developer uses that for experiment. Let us fun following query. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result. When we look at above resultset it is very clear that LEAD function gives us value which is going to come in next line and LAG function gives us value which was encountered in previous line. If we have to generate the same result without using this function we will have to use self join. In future blog post we will see the same. Let us explore this function a bit more. This function not only provide previous or next line but it can also access any line before or after using offset. Let us fun following query, where LEAD and LAG function accesses the row with offset of 2. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID,2) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID,2) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result. You can see the LEAD and LAG functions  now have interval of  rows when they are returning results. As there is interval of two rows the first two rows in LEAD function and last two rows in LAG function will return NULL value. You can easily replace this NULL Value with any other default value by passing third parameter in LEAD and LAG function. Let us fun following query. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID,2,0) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID,2,0) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result, where NULL are now replaced with value 0. Just like any other analytic function we can easily partition this function as well. Let us see the use of PARTITION BY in this clause. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result, where now the data is partitioned by SalesOrderID and LEAD and LAG functions are returning the appropriate result in that window. As now there are smaller partition in my query, you will see higher presence of NULL. In future blog post we will see how this functions are compared to SELF JOIN. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • 1D Function into 2D Function Interpolation

    - by Drazick
    Hello. I have a 1D function which I want to interpolate into 2D function. I know the function should have "Polar Symmetry". Hence I use the following code (Matlab Syntax): Assuming the 1D function is LSF of the length 15. [x, y] = meshgrid([-7:7]); r = sqrt(x.^2 + y.^2); PSF = interp1([-7:7], LSF, r(:)); % Sometimes using 'spline' option, same results. PSF = reshape(PSF, [7, 7]); I have few problems: 1. Got some overshoot at the edges (As there some Extrapolation). 2. Can't enforce some assumptions (Monotonic, Non Negative). Is there a better Interpolation method for those circumstances? I couldn't find "Lanczos" based interpolation I can use the same way as interp1 (For a certain vector of points, in "imresize" you can only set the length). Is there such function anywhere? Has anyone encountered a function which allows enforcing some assumptions (Monotonically Decreasing, Non Negative, etc..). Thanks.

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  • Function within function in R

    - by frespider
    Can you please explain to me why th code complain saying that Samdat is not found? I am trying to switch between the models as you can see, so i declared a functions that contains these specific models and I just need to call these function as one of the argument in the get.f function where the resampling will change the structure for each design matrix in the model. the code complain the Samdat is not found when it is found. Also, is there a way I can make the condition statement as if(Model == M1()) instead I have to create another argument M to set if(M==1) Can you explain please? dat <- cbind(Y=rnorm(20),rnorm(20),runif(20),rexp(20),rnorm(20),runif(20), rexp(20),rnorm(20),runif(20),rexp(20)) nam <- paste("v",1:9,sep="") colnames(dat) <- c("Y",nam) M1 <- function(){ a1 = cbind(Samdat[,c(2:5,7,9)]) b1 = cbind(Samdat[,c(2:4,6,8,7)]) c1 = b1+a1 list(a1=a1,b1=b1,c1=c1)} M2 <- function(){ a1= cbind(Samdat[,c(2:5,7,9)])+2 b1= cbind(Samdat[,c(2:4,6,8,7)])+2 c1 = a1+b1 list(a1=a1,b1=b1,c1=c1)} M3 <- function(){ a1= cbind(Samdat[,c(2:5,7,9)])+8 b1= cbind(Samdat[,c(2:4,6,8,7)])+8 c1 = a1+b1 list(a1=a1,b1=b1,c1=c1)} ################################################################# get.f <- function(asim,Model,M){ sse <-c() for(i in 1:asim){ set.seed(i) Samdat <- dat[sample(1:nrow(dat),nrow(dat),replace=T),] Y <- Samdat[,1] if(M==1){ a2 <- Model$a1 b2 <- Model$b1 c2 <- Model$c1 s<- a2+b2+c2 fit <- lm(Y~s) cof <- sum(summary(fit)$coef[,1]) coff <-Model$cof sse <-c(sse,coff) } else if(M==2){ a2 <- Model$a1 b2 <- Model$b1 c2 <- Model$c1 s<- c2+12 fit <- lm(Y~s) cof <- sum(summary(fit)$coef[,1]) coff <-Model$cof sse <-c(sse,coff) } else { a2 <- Model$a1 b2 <- Model$b1 c2 <- Model$c1 s<- c2+a2 fit <- lm(Y~s) cof <- sum(summary(fit)$coef[,1]) coff <- Model$cof sse <-c(sse,coff) } } return(sse) } get.f(10,Model=M1(),M=1) get.f(10,Model=M2(),M=2) get.f(10,Model=M3(),M=3)

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  • How to Create Element in XSLT When Copying Using Templates

    - by John Dumont
    Hello, I'm trying to create an element in an XML where the basic content is copied and modified. My XML is something like <root> <node> <child>value</child> <child2>value2</child2> </node> <node2>bla</node2> </root> The number of children of node may change as well as the children of root. The XSLT should copy the whole content, modify some values and add some new. The copying and modifying is no problem: <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0"> <xsl:output method="xml" encoding="UTF-8"/> <xsl:template match="@*|node()"> <xsl:copy> <xsl:apply-templates select="@*|node()"/> </xsl:copy> </xsl:template> </xsl:stylesheet> (+ further templates for modifications). But how do I add a new element in this structure on some path, e.g. I want to add an element as the last element of the "node" node. The "node" element itself always exists.

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  • How to pass a function in a function?

    - by SoulBeaver
    That's an odd title. I would greatly appreciate it if somebody could clarify what exactly I'm asking because I'm not so sure myself. I'm watching the Stanford videos on Programming Paradigms(that teacher is awesome) and I'm up to video five when he started doing this: void *lSearch( void* key, void* base, int elemSize, int n, int (*cmpFn)(void*, void*)) Naturally, I thought to myself, "Oi, I didn't know you could declare a function and define it later!". So I created my own C++ test version. int foo(int (*bar)(void*, void*)); int bar(void* a, void* b); int main(int argc, char** argv) { int *func = 0; foo(bar); cin.get(); return 0; } int foo(int (*bar)(void*, void*)) { int c(10), d(15); int *a = &c; int *b = &d; bar(a, b); return 0; } int bar(void* a, void* b) { cout << "Why hello there." << endl; return 0; } The question about the code is this: it fails if I declare function int *bar as a parameter of foo, but not int (*bar). Why!? Also, the video confuses me in the fact that his lSearch definition void* lSearch( /*params*/ , int (*cmpFn)(void*, void*)) is calling cmpFn in the definition, but when calling the lSearch function lSearch( /*params*/, intCmp ); also calls the defined function int intCmp(void* elem1, void* elem2); and I don't get how that works. Why, in lSearch, is the function called cmpFn, but defined as intCmp, which is of type int, not int* and still works? And why does the function in lSearch not have to have defined parameters?

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  • C when to allocate and free memory - before function call, after function call...etc

    - by Keith P
    I am working with my first straight C project, and it has been a while since I worked on C++ for that matter. So the whole memory management is a bit fuzzy. I have a function that I created that will validate some input. In the simple sample below, it just ignores spaces: int validate_input(const char *input_line, char* out_value){ int ret_val = 0; /*false*/ int length = strlen(input_line); cout << "length = " << length << "\n"; out_value =(char*) malloc(sizeof(char) * length + 1); if (0 != length){ int number_found = 0; for (int x = 0; x < length; x++){ if (input_line[x] != ' '){ /*ignore space*/ /*get the character*/ out_value[number_found] = input_line[x]; number_found++; /*increment counter*/ } } out_value[number_found + 1] = '\0'; ret_val = 1; } return ret_val; } Instead of allocating memory inside the function for out_value, should I do it before I call the function and always expect the caller to allocate memory before passing into the function? As a rule of thumb, should any memory allocated inside of a function be always freed before the function returns?

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  • calling java script function then C# function after clicking ASP.NET button

    - by Eyla
    I have this serious: I have ASP.NET page, This page contents Update panel with ASP.NET control. I have Java script function to do validation so when I click the button I will use onclientclick to call the java function to do the validation and after this one done should call then event click button function from code behind. I tried vew methods but they did not work for me. here is sample of my code that after I click the button onclientclick will call the java script function for validation and if the validation is OK should call onclick event. .................... java script function ........................ <script type="text/javascript" > function add(){ if (tag == trye) { document.getElementById('<%=btnInfor.ClientID%>').click(); alert("DataAdded") } else { alert("Requiered Field Missing.") return false; } } </script> ..................... ASP.NET button ................... <asp:Button ID="btnInfor" runat="server" Text="Add Information" Style="position: absolute; top: 1659px; left: 433px;" onclientclick="JavaScript: return myAdd()" /> .................... code behind in C# ...................... protected void btnInfor_Click(object sender, EventArgs e) { \\mycode }

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  • jQuery broken function after added new function

    - by Kyle Sevenoaks
    What's wrong here? The alert function was working until I added this new function to it. Is there anything I am doing wrong? It just simply doesn't fire the alert anymore. <input value="1" type="checkbox" name="salgsvilkar" id="checkbox2" style="float:left;" /> {literal} <script src="http://code.jquery.com/jquery-latest.js"></script> <script type="text/javascript"> $(function() { //checkbox $("#scrollwrap").click(function(){ $("#scrollwrap").toggleClass('highlight'); });? }); $(function(){ //button $("#fullfor_btn").click(function(e){ if(!$("#checkbox2").is(':checked') == false) { alert("Please accept the terms of sale."); e.preventDefault(); } }); }); </script> {/literal} <button type="submit" class="submit" name="{$method}" id="fullfor_btn" title="Fullfør bestillingen nå" value="">&nbsp;</button>

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  • Using pointers in PHP.

    - by Babiker
    I ask this question because i learned that in programming and designing, you must have a good reason for decisions. I am php learner and i am at a crossroad here, i am using simple incrementation to try to get what im askin across. I am certainly not here to start a debate about the pros/cons of pointers but when it comes to php, which is the better programming practice: function increment(&$param) { $param++; } Or function increment($param){ return $param++; } $param = increment($param);

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