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  • C++: Cannot convert from foo& to foo*

    - by Rosarch
    I have a method: odp(foo& bar); I'm trying to call it: foo baz; odp(&baz); I get a compiler error: error C2664: "odp" cannot convert parameter 1 from 'foo *' to 'foo &' What am I doing wrong? Aren't I passing in a reference to baz? UPDATE: Perhaps I have a misconception about the relationship between pointers and references. I thought that they were the same, except references couldn't be null. Is that incorrect?

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  • jQuery: Need to "refresh" a widget.

    - by Legend
    I am adapting the Coverflow technique to work with a div. The coverflow function (included as a js file in the head section) is here. When I dynamically add a DIV, it doesn't show up in the coverflow. I am wondering if there is a way to add a destroy function to this js file so that whenever a new div add is added, I can call the destroy method and then reinstantiate. Any suggestions on how I should go about doing this?

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  • When setting a form's opacity should I use a decimal or double?

    - by Eggs McLaren
    I'm new to C#, and I want to use a track-bar to change a form's opacity. This is my code: decimal trans = trackBar1.Value / 5000 this.Opacity = trans When I try to build it, I get this error: Cannot implicitly convert type 'decimal' to 'double' I tried making trans a double, but then the control doesn't work. This code worked fine for me in VB.NET. What do I need to do differently?

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  • What are good resources for computer graphics basics?

    - by Hanno Fietz
    During Flex programming, I recently ran into several questions (about box models, ways to join lines and misaligning pixels [on doctype]) regarding computer graphics and layout, where I felt that I lacked some basic background on things like concepts like the box model approaches mapping real numbers to a pixel raster (like font anti-aliasing) conventions found across drawing engines, like do you count y coordinates from top or bottom, and why I feel that reading some basic Wikipedia articles, books or tutorials on these subjects might help in phrasing my questions more specifically and debugging my code more systematically. I have repeatedly found myself writing tiny test apps in Flex, just to find out how the APIs do very basic stuff. My assumption would be that if I knew the right vocabulary and some general concepts, I could solve these questions much faster.

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  • Model in sub-directory via app_label?

    - by prometheus
    In order to place my models in sub-folders I tried to use the app_label Meta field as described here. My directory structure looks like this: project apps foo models _init_.py bar_model.py In bar_model.py I define my Model like this: from django.db import models class SomeModel(models.Model): field = models.TextField() class Meta: app_label = "foo" I can successfully import the model like so: from apps.foo.models.bar_model import SomeModel However, running: ./manage.py syncdb does not create the table for the model. In verbose mode I do see, however, that the app "foo" is properly recognized (it's in INSTALLED_APPS in settings.py). Moving the model to models.py under foo does work. Is there some specific convention not documented with app_label or with the whole mechanism that prevents this model structure from being recognized by syncdb?

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  • returning reference to a vector from a method and using its public members

    - by memC
    dear experts, I have a vector t_vec that stores references to instances of class Too. The code is shown below. In the main , I have a vector t_vec_2 which has the same memory address as B::t_vec. But when I try to access t_vec_2[0].val1 it gives error val1 not declared. Could you please point out what is wrong? Also, if you know of a better way to return a vector from a method, please let me know! Thanks in advance. class Too { public: Too(); ~Too(){}; int val1; }; Too::Too(){ val1 = 10; }; class B { public: vector<Too*> t_vec; Too* t1; vector<Too*>& get_tvec(); B(){t1 = new Too();}; ~B(){delete t1;}; }; vector<Too*>& B::get_tvec(){ t_vec.push_back(t1); return t_vec; } int main(){ B b; b = B(); vector<Too*>& t_vec_2 = b.get_tvec(); // Getting error std::cout << "\n val1 = " << t_vec_2[0].val1; return 0; }

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  • Definition of variables/fields type within a constructor, how is it done?

    - by elementz
    I just had a look at Suns Java tutorial, and found something that totally confused me: Given the following example: public Bicycle(int startCadence, int startSpeed, int startGear) { gear = startGear; cadence = startCadence; speed = startSpeed; } Why is it, that the types of the variables (fields?) gear, cadence and speed do not need to be defined? I would have written it as follows: public Bicycle(int startCadence, int startSpeed, int startGear) { int gear = startGear; int cadence = startCadence; int speed = startSpeed; } What would be the actual differnce?

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  • array, I/O file and standard deviation (c++)

    - by JohnWong
    double s_deviation(double data[],int cnt, double mean) { int i; double sum= 0; double sdeviation; double x; //x = mean(billy,a_size); for(i=0; i<cnt; i++) { sum += ((data[i]) - (mean)); } sdeviation = sqrt(sum/((double)cnt)); return sdeviation; } When I cout the result from this function, it gave me NaN. I tested the value of (mean) and data[i] using return data[i] and return mean they are valid. when i replaced mean with an actual number, the operation returned a finite number. but with mean as a variable, it produced NaH. I can't see anything wrong with my code at the moment. Again, I am sure mean, data are getting the right number based on those tests. Thank you

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  • JavaScript: How is "function x() {}" different from "x = function() {}" ?

    - by jleedev
    In the answers to this question, we read that function f() {} defines the name locally, while [var] f = function() {} defines it globally. That makes perfect sense to me, but there's some strange behavior that's different between the two declarations. I made an HTML page with the script onload = function() { alert("hello"); } and it worked as expected. When I changed it to function onload() { alert("hello"); } nothing happened. (Firefox still fired the event, but WebKit, Opera, and Internet Explorer didn't, although frankly I've no idea which is correct.) In both cases (in all browsers), I could verify that both window.onload and onload were set to the function. In both cases, the global object this is set to the window, and I no matter how I write the declaration, the window object is receiving the property just fine. What's going on here? Why does one declaration work differently from the other? Is this a quirk of the JavaScript language, the DOM, or the interaction between the two?

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  • How do Arrays work in C#?

    - by Slateboard
    I know that they are used to store data, but I have a difficult time understanding exactly how to use them in a program. In addition, I found this site with a tetris clone tutorial (the actual tutorial is missing). It uses arrays, but I can't really make sense of how it works. Here's an example of the code - public int[, ,] TShape = new int[4, 4, 2] { {{1, 0}, {0, 1}, {1, 1}, {2, 1}}, {{1, 0}, {0, 1}, {1, 1}, {1, 2}}, {{0, 0}, {1, 0}, {2, 0}, {1, 1}}, {{0, 0}, {0, 1}, {1, 1}, {0, 2}}}; Could it be that I'm looking too hard into this, or perhaps there's something I'm not grasping about it?

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  • convert string to dict using list comprehension in python

    - by Pavel
    I have came across this problem a few times and can't seem to figure out a simple solution. Say I have a string string = "a=0 b=1 c=3" I want to convert that into a dictionary with a, b and c being the key and 0, 1, and 3 being their respective values (converted to int). Obviously I can do this: list = string.split() dic = {} for entry in list: key, val = entry.split('=') dic[key] = int(val) But I don't really like that for loop, It seems so simple that you should be able to convert it to some sort of list comprehension expression. And that works for slightly simpler cases where the val can be a string. dic = dict([entry.split('=') for entry in list]) However, I need to convert val to an int on the fly and doing something like this is syntactically incorrect. dic = dict([[entry[0], int(entry[1])] for entry.split('=') in list]) So my question is: is there a way to eliminate the for loop using list comprehension? If not, is there some built in python method that will do that for me?

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  • How to convert list into a string?

    - by PARIJAT
    I have extracted some data from the file and want to write it in the file 2 but the program says 'sequence item 1: expected string, list found', I want to know how I can convert buffer[] i.e. string into sequence, so that it could be saved in file 2. file = open('/ddfs/user/data/k/ktrip_01/hmm.txt','r') file2 = open('/ddfs/user/data/k/ktrip_01/hmm_write.txt','w') buffer = [] rec = file.readlines() for line in rec : field = line.split() print '>',field[0] term = field[0] buffer.append(term) print field[1], field[2], field[6], field[12] term1 = field [1] buffer.append(term1) term2 = field[2] buffer.append[term2] term3 = field[6] buffer.append[term3] term4 = field[12] buffer.append[term4] file2.write(buffer) file.close() file2.close()

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  • TB3.0.10: Messages being sent back to me

    - by punkinette64
    Hello, I don't know if this will make any sense to you; but here goes. When I send an email and I get a response, more often than not, in the 'to:' is my email address. However, my email address also ends up in the 'from' column.The 'reply-from' address is nowhere to be found;so I don't have any address with which I can send my reply, as both of them have just my email address. What am I doing wrong here? Is there some set-up in my TOOLOPTIONS set-up incorrectly? The set-up in OPTIONS is pretty difficult to understand and it doesn't offer any 'to' or 'reply-from' choices. This is critical because I just cannot answer my emails because there is no one I can send a reply to. Please, please try to help me. If you have the answer, please email me at: [email protected] Thank you. Blessings. Shiloh

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  • Returning currently displayed index of an array Javascript...

    - by Jeff Kindred
    I have a simple array with x number of items. I am displaying them individually via a link click... I want to update a number that say 1 of 10. when the next one is displayed i want it to display 2 of 10 etc... I have looked all around and my brain is fried right now... I know its simple I just cant get it out. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title>Page Title</title> <link rel="stylesheet" href="style.css" type="text/css" media="screen" charset="utf-8"/> <script type="text/javascript"> var quotations = new Array() quotations[0]= "1" quotations[1]= "2" quotations[2]= "3" quotations[3]= "4" quotations[4]= "5" quotations[5]= "6" quotations[6]= "7" numQuotes = quotations.length; curQuote = 1; function move( xflip ) { curQuote = curQuote + xflip; if (curQuote > numQuotes) { curQuote = 1 ; } if (curQuote == 0) { curQuote = numQuotes ; } document.getElementById('quotation').innerHTML=quotations[curQuote - 1]; } var curPage = //this is where the current index should go </script> </head> <body> <div id="quotation"> <script type="text/javascript">document.write(quotations[0]);</script> </div> <div> <p><a href="javascript();" onclick="move(-1)">GO back</a> <script type="text/javascript">document.write(curPage + " of " + numQuotes)</script> <a href="javascript();" onclick="move(1)">GO FORTH</a></p> </div> </body> </html>

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  • A general question about compilation and interpretation.

    - by wucnuc
    Hi stackoverflow, I apologize in advance for the possible stupidity of this question. However, the following has been the source of some confusion for me and I know the people here will be able to handily clear up the confusion for me. Basically, I would like to finally understand the relationship between any and all of the following terms. Some of the terms I do actually understand pretty well, but some of them are similar in my mind and I would like to once and for all to see their relationships/distinctions laid out all at once. They are: compiler interpreter bytecode machine code assembler assembly language binary object code executable Ideally, an answer would use examples from Java and C++ and other well-known programming languages that a young-ish student like me would be familiar with. Also, if you want to throw in any other useful terms that would be fine too :)

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  • do the Python libraries have a natural dependence on the global namespace?

    - by msw
    I first ran into this when trying to determine the relative performance of two generators: t = timeit.repeat('g.get()', setup='g = my_generator()') So I dug into the timeit module and found that the setup and statement are evaluated with their own private, initially empty namespaces so naturally the binding of g never becomes accessible to the g.get() statement. The obvious solution is to wrap them into a class, thus adding to the global namespace. I bumped into this again when attempting, in another project, to use the multiprocessing module to divide a task among workers. I even bundled everything nicely into a class but unfortunately the call pool.apply_async(runmc, arg) fails with a PicklingError because buried inside the work object that runmc instantiates is (effectively) an assignment: self.predicate = lambda x, y: x > y so the whole object can't be (understandably) pickled and whereas: def foo(x, y): return x > y pickle.dumps(foo) is fine, the sequence bar = lambda x, y: x > y yields True from callable(bar) and from type(bar), but it Can't pickle <function <lambda> at 0xb759b764>: it's not found as __main__.<lambda>. I've given only code fragments because I can easily fix these cases by merely pulling them out into module or object level defs. The bug here appears to be in my understanding of the semantics of namespace use in general. If the nature of the language requires that I create more def statements I'll happily do so; I fear that I'm missing an essential concept though. Why is there such a strong reliance on the global namespace? Or, what am I failing to understand? Namespaces are one honking great idea -- let's do more of those!

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  • Java: calculate linenumber from charwise position according to the number of "\n"

    - by HH
    I know charwise positions of matches like 1 3 7 8. I need to know their corresponding line number. Example: file.txt Match: X Mathes: 1 3 7 8. Want: 1 2 4 4 $ cat file.txt X2 X 4 56XX [Added: does not notice many linewise matches, there is probably easier way to do it with stacks] $ java testt 1 2 4 $ cat testt.java import java.io.*; import java.util.*; public class testt { public static String data ="X2\nX\n4\n56XX"; public static String[] ar = data.split("\n"); public static void main(String[] args){ HashSet<Integer> hs = new HashSet<Integer>(); Integer numb = 1; for(String s : ar){ if(s.contains("X")){ hs.add(numb); numb++; }else{ numb++; } } for (Integer i : hs){ System.out.println(i); } } }

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  • passing a class method as opposed to a function in std::sort

    - by memC
    hi, Within a class, I am trying to sort a vector, by passing a method of the same class. But it gives errors at the time of compilation. Can anyone tell what the problem is? Thank you! it gives the following error: argument of type bool (Sorter::)(D&, D&)' does not matchbool (Sorter::*)(D&, D&)' I have also tried using sortBynumber(D const& d1, D const& d2) #include<vector> #include<stdio.h> #include<iostream> #include<algorithm> class D { public: int getNumber(); D(int val); ~D(){}; private: int num; }; D::D(int val){ num = val; }; int D::getNumber(){ return num; }; class Sorter { public: void doSorting(); bool sortByNumber(D& d1, D& d2); std::vector<D> vec_D; Sorter(); ~Sorter(){}; private: int num; }; Sorter::Sorter(){ int i; for ( i = 0; i < 10; i++){ vec_D.push_back(D(i)); } }; bool Sorter::sortByNumber(D& d1, D& d2){ return d1.getNumber() < d2.getNumber(); }; void Sorter::doSorting(){ std::sort(vec_D.begin(), vec_D.end(), this->sortByNumber); }; int main(){ Sorter s; s.doSorting(); std::cout << "\nPress RETURN to continue..."; std::cin.get(); return 0; }

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  • Using mercurial for web-design version control (dealing with images)

    - by Acorn
    I'm very new to Version Control, and I was wondering if I could get some advice on how it can fit into website design. At the moment I'm working on a typical, simple website that includes images: A few .html files and a .css file One folder full of photographs Another folder with the corresponding thumbnails Can I just put the whole lot in a repository? Or is there a better way I could apply Version Control to it? How should I deal with the images? edit: How well will it work with changes to the images? What if I decide to try and optimise my photographs or resize them. I wont be able to see what exactly changed about the images, should comments be enough to keep track of that?

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  • How do I splice a python string programmatically?

    - by Robin Welch
    Very simple question, hopefully. So, in Python you can split up strings using indices as follows: >>> a="abcdefg" >>> print a[2:4] cd but how do you do this if the indices are based on variables? E.g. >>> j=2 >>> h=4 >>> print a[j,h] Traceback (most recent call last): File "<stdin>", line 1, in ? TypeError: string indices must be integers

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  • Regular Expression Sanitize (PHP)

    - by atif089
    Hello, I would like to sanitize a string in to a URL so this is what I basically need. Everything must be removed except alphanumeric characters and spaces and dashed. Spaces should be converter into dashes. Eg. This, is the URL! must return this-is-the-url Thanks

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