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• Modify passed, nested dict/list

  - by Gerenuk

  I was thinking of writing a function to normalize some data. A simple approach is def normalize(l, aggregate=sum, norm_by=operator.truediv): aggregated=aggregate(l) for i in range(len(l)): l[i]=norm_by(l[i], aggregated) l=[1,2,3,4] normalize(l) l -> [0.1, 0.2, 0.3, 0.4] However for nested lists and dicts where I want to normalize over an inner index this doesnt work. I mean I'd like to get l=[[1,100],[2,100],[3,100],[4,100]] normalize(l, ?? ) l -> [[0.1,100],[0.2,100],[0.3,100],[0.4,100]] Any ideas how I could implement such a normalize function? Maybe it would be crazy cool to write normalize(l[...][0]) Is it possible to make this work?? Or any other ideas? Also not only lists but also dict could be nested. Hmm... EDIT: I just found out that numpy offers such a syntax (for lists however). Anyone know how I would implement the ellipsis trick myself?

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• XPath: limit scope of result set

  - by Laramie

  Given the XML <a> <c> <b id="1" value="noob"/> </c> <b id="2" value="tube"/> <a> <c> <b id="3" value="foo"/> </c> <b id="4" value="goo"/> <b id="5" value="noob"/> <a> <b id="6" value="near"/> <b id="7" value="bar"/> </a> </a> </a> and the Xpath 1.0 query //b[@id=2]/ancestor::a[1]//b[@value="noob"] is there some way to limit the result set to the <b> elements that are ONLY the children of the immediate <a> element of the start node (//b[@id=2])? For example the Xpath above returns both node ids 1 and 5. The goal is to limit the result to just node id=1 since it is the only @value="noob" element in the same <c> group as our start node (//b[@id=2]). In English, "Starting at a node whose id is equal to 2, find all the elements whose value is "noob" that are descendants of the immediate parent c element without passing through another c element".

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• C#: Using one Data Table in order to fill 2 different comboboxes?

  - by odiseh

  Hi all. I have 2 comboboxes on a form (form1) called combobox1 and combobox2. Each comboboxes should be filled with data stored in 2 different tables in Sql server 2005: table1 and table2 I mean: combobox1 -- table1 combobox2 -- table2 I fill data table with proper data and then bind the comboboxes to it separately. My problem is: after filling 2 combos, both of them have equal data got from table2. This is my code: DataTable tb1 = new DataTable(); //Filling tb1 with data got from table1 combobox1.Items.Clear(); combobox1.DataSource = tb1; combobox1.DisplayMember = "Name"; combobox1.ValueMember = "ID"; combobox1.SelectedIndex = -1; //filling tb1 with data got from table2 combobox2.Items.Clear(); combobox2.DataSource = tb1; combobox2.DisplayMember = "Name"; combobox2.ValueMember = "ID"; combobox2.SelectedIndex = -1; What's wrong? It seems that if I get 2 different data tables (tb1 and tb2) , every thing will be all right. Any suggestions please. Thank you

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• How to achieve interaction between GUI class with logic class

  - by volting

  Im new to GUI programming, and haven't done much OOP. Im working on a basic calculator app to help me learn GUI design and to brush up on OOP. I understand that anything GUI related should be kept seperate from the logic, but Im unsure how to implement interaction between logic an GUI classes when needed i.e. basically passing variables back and forth... Im using TKinter and when I pass a tkinter variable to my logic it only seems to hold the string PY_VAR0. def on_equal_btn_click(self): self.entryVariable.set(self.entryVariable.get() + "=") calculator = Calc(self.entryVariable) self.entryVariable.set(calculator.calculate()) Im sure that im probably doing something fundamentally wrong and probabaly really stupid, I spent a considerable amount of time experimenting (and searching for answers online) but Im getting no where. Any help would be appreciated. Thanks, V The Full Program (well just enough to show the structure..) import Tkinter class Gui(Tkinter.Tk): def __init__(self,parent): Tkinter.Tk.__init__(self,parent) self.parent = parent self.initialize() def initialize(self): self.grid() self.create_widgets() """ grid config """ #self.grid_columnconfigure(0,weight=1,pad=0) self.resizable(False, False) def create_widgets(self): """row 0 of grid""" """Create Text Entry Box""" self.entryVariable = Tkinter.StringVar() self.entry = Tkinter.Entry(self,width=30,textvariable=self.entryVariable) self.entry.grid(column=0,row=0, columnspan = 3 ) self.entry.bind("<Return>", self.on_press_enter) """create equal button""" equal_btn = Tkinter.Button(self,text="=",width=4,command=self.on_equal_btn_click) equal_btn.grid(column=3, row=0) """row 1 of grid""" """create number 1 button""" number1_btn = Tkinter.Button(self,text="1",width=8,command=self.on_number1_btn_click) number1_btn.grid(column=0, row=1) . . . def on_equal_btn_click(self): self.entryVariable.set(self.entryVariable.get() + "=") calculator = Calc(self.entryVariable) self.entryVariable.set(calculator.calculate()) class Calc(): def __init__(self, equation): self.equation = equation def calculate(self): #TODO: parse string and calculate... return self.equation if __name__ == "__main__": app = Gui(None) app.title('Calculator') app.mainloop()

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• Selections and radioing - JavaScript

  - by Wayne

  I have a list like this: <ul> <li id="adm-thumb" onclick="javascript:addBanner('bowling.jpg');"> <div class="adm-tick"></div> <img src="img/banners/bowling.jpg" /></li> <li id="adm-thumb" onclick="javascript:addBanner('kcc.jpg');"> <div class="adm-tick"></div> <img src="img/banners/kcc.jpg" /></li> <li id="adm-thumb" onclick="javascript:addBanner('paintballing.png');"> <div class="adm-tick"></div> <img src="img/banners/paintballing.png" /></li> </ul> <input id="bannername" type="text" /> When one item is clicked, the value inside the addBanner() will be added to the input field, however, I want one list to be selected (which is done by css to make it look like it has) when it is equal to the value of the input value. If the value is equals to the value in the addBanner value then the clicked item should have a red background. e.g. function addBanner(label) { var Field = document.getElementById('bannername'); Field.value = label; if(Field.value != label) { // I have no idea what to put here } } Something like a div button that acts like a radio button.

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• How do I debug JavaScript .onlick event?

  - by user3700824

  I'm learning JavaScript but seem to be having a problem. I have a piece of code that is executed when the page is fully loaded. The function then gathers all the button elements on my HTML page. From here I loop through getting each button's title attribute and then assign an onclick event to the button that is equal to a function that writes to the console.log with the title. I have tried various ways of doing this but it is not working. Here is the JavaScript code that I'm working with. Currently all it does is loop through calling the function and logging the tile to the console.log, but this is not supposed to happen. Each time I click the button it should call the function with its title and log that. window.onload = myPageIsReady; function myPageIsReady(){ var myList = document.getElementsByTagName("button"); var myTitle = []; for(var i = 0; i < myList.length; i++){ myTitle[i] = myList[i].getAttribute("title"); myList[i].onclick = getMyTitle(myTitle[i]); }; function getMyTitle(myTitle){ console.log(myTitle); }; };

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• Toggle table row siblings

  - by kuswantin

  I have a table structured like this: <table> <tr id="id1" class="parent"></tr> <tr class="id1"></tr> <tr class="id1"></tr> <tr class="id1"></tr> <tr class="id1"></tr> <tr id="id2" class="parent"></tr> <tr class="id2"></tr> <tr class="id2"></tr> <tr class="id2"></tr> <tr class="id2"></tr> .....etc </table> As you can see child classes are coresponding to their parent id. Now I want to toggle all the rows which have class names equal to their parent row id whenever parent row is clicked. I have tried this, perhaps stupid try:) and can't seem to get this working: $('tr.parent').click(function() { //alert('yay'); var tog = $(this).attr('id'); $(this).siblings().hasClass(tog).slideToggle(); return false; }); Thanks.

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• Circumvent c++ null-terminated string frustration

  - by ypnos

  I'm using boost::program_options and it suffers from the same as many other c++ libs, even std itself: It still uses C-style null-terminated strings, because nobody really likes the weak std::string. The method in question is: options_description_easy_init& operator()(const char* name, const value_semantic* s, const char* description); The typical use case is just fine: options.add_options() ("graphical", bool_switch(&isGraphical)->default_value(false), "Show any graphical output during runtime") However, I need the name of the option to be set dynamically. The reason is that in some cases I nead a custom prefix, which is added to the string by my function std::string key(const std::string& k): options.add_options() (key("graphical"), bool_switch(&isGraphical)->default_value(false), "Show any graphical output during runtime") This fails. I could now use c_str() on the std::string but that's evil -- I don't know how long program_options keeps the variable around and if my string is still alive when needed. I could also reserve memory in a buffer etc. and hand in that. The buffer is never freed and it sucks/is evil. Is there anything else I can do to circumvent the C-style string mess in this situation?

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• C# Type conversion between two similar Datatable objects

  - by Ali

  I have .NET project with sync framework and two separate Datasets for MS SQL and Compact SQL. in my base class I have a generic DataTable object. in my derived classed I assign Typed DataTable to the generic object based on whether the application is operating online or offline: example: if (online) _dataTable = new MSSQLDataSet.Customer; else _dataTable = new CompactSQLDataSet.Customer; Now every where in my code i have to check and do a cast based on the current network mode like this: public void changeCustomerID(int ID) { if (online) (MSSQLDataSet.CustomerDataTable)_dataTable)[i].CustomerID = value; else (CompactMSSQLDataSet.CustomerDataTable)_dataTable)[i].CustomerID = value; } but I don't think this is very efficient and I believe it can be done in a smarter way to only use one line of code by dynamically getting the Type of _dataTable on the run time. my problem is at the design time, in order to acess datatable porperties such as "CustomerID" it has to be casted to either MSSQLDataSet.CustomerDataTable or CompactMSSQLDataSet.CustomerDataTable. Is there a way to have a function or a operator to convert the _datatable to its runtime type but still be able to use it's design time properties which are the same between the two types? something like: ((aType)_dataTable)[i].CustomerID = value; //or GetRuntimeType(_dataTable)[i].CustomerID = value;

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• How to write a custom predicate for multi_index_containder with composite_key?

  - by Titan

  I googled and searched in the boost's man, but didn't find any examples. May be it's a stupid question...anyway. So we have the famous phonebook from the man: typedef multi_index_container< phonebook_entry, indexed_by< ordered_non_unique< composite_key< phonebook_entry, member<phonebook_entry,std::string,&phonebook_entry::family_name>, member<phonebook_entry,std::string,&phonebook_entry::given_name> >, composite_key_compare< std::less<std::string>, // family names sorted as by default std::greater<std::string> // given names reversed > >, ordered_unique< member<phonebook_entry,std::string,&phonebook_entry::phone_number> > > > phonebook; phonebook pb; ... // look for all Whites std::pair<phonebook::iterator,phonebook::iterator> p= pb.equal_range(boost::make_tuple("White"), my_custom_comp()); How should my_custom_comp() look like? I mean it's clear for me then it takes boost::multi_index::composite_key_result<CompositeKey> as an argumen (due to compilation errors :) ), but what is CompositeKey in that particular case? struct my_custom_comp { bool operator()( ?? boost::multi_index::composite_key_result<CompositeKey> ?? ) const { return blah_blah_blah; } }; Thanks in advance.

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• How can variadic char template arguments from user defined literals be converted back into numeric types?

  - by Pubby

  This question is being asked because of this one. C++11 allows you to define literals like this for numeric literals: template<char...> OutputType operator "" _suffix(); Which means that 503_suffix would become <'5','0','3'> This is nice, although it isn't very useful in the form it's in. How can I transform this back into a numeric type? This would turn <'5','0','3'> into a constexpr 503. Additionally, it must also work on floating point literals. <'5','.','3> would turn into int 5 or float 5.3 A partial solution was found in the previous question, but it doesn't work on non-integers: template <typename t> constexpr t pow(t base, int exp) { return (exp > 0) ? base * pow(base, exp-1) : 1; }; template <char...> struct literal; template <> struct literal<> { static const unsigned int to_int = 0; }; template <char c, char ...cv> struct literal<c, cv...> { static const unsigned int to_int = (c - '0') * pow(10, sizeof...(cv)) + literal<cv...>::to_int; }; // use: literal<...>::to_int // literal<'1','.','5'>::to_int doesn't work // literal<'1','.','5'>::to_float not implemented

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• Matching on search attributes selected by customer on front end

  - by CodeNinja1974

  I have a method in a class that allows me to return results based on a certain set of Customer specified criteria. The method matches what the Customer specifies on the front end with each item in a collection that comes from the database. In cases where the customer does not specify any of the attributes, the ID of the attibute is passed into the method being equal to 0 (The database has an identity on all tables that is seeded at 1 and is incremental). In this case that attribute should be ignored, for example if the Customer does not specify the Location then customerSearchCriteria.LocationID = 0 coming into the method. The matching would then match on the other attributes and return all Locations matching the other attibutes, example below: public IEnumerable<Pet> FindPetsMatchingCustomerCriteria(CustomerPetSearchCriteria customerSearchCriteria) { if(customerSearchCriteria.LocationID == 0) { return repository.GetAllPetsLinkedCriteria() .Where(x => x.TypeID == customerSearchCriteria.TypeID && x.FeedingMethodID == customerSearchCriteria.FeedingMethodID && x.FlyAblityID == customerSearchCriteria.FlyAblityID ) .Select(y => y.Pet); } } The code for when all criteria is specified is shown below: private PetsRepository repository = new PetsRepository(); public IEnumerable<Pet> FindPetsMatchingCustomerCriteria(CustomerPetSearchCriteria customerSearchCriteria) { return repository.GetAllPetsLinkedCriteria() .Where(x => x.TypeID == customerSearchCriteria.TypeID && x.FeedingMethodID == customerSearchCriteria.FeedingMethodID && x.FlyAblityID == customerSearchCriteria.FlyAblityID && x.LocationID == customerSearchCriteria.LocationID ) .Select(y => y.Pet); } I want to avoid having a whole set of if and else statements to cater for each time the Customer does not explicitly select an attribute of the results they are looking for. What is the most succint and efficient way in which I could achieve this?

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• Instrumenting a string

  - by George Polevoy

  Somewhere in C++ era i have crafted a library, which enabled string representation of the computation history. Having a math expression like: TScalar Compute(TScalar a, TScalar b, TScalar c) { return ( a + b ) * c; } I could render it's string representation: r = Compute(VerbalScalar("a", 1), VerbalScalar("b", 2), VerbalScalar("c", 3)); Assert.AreEqual(9, r.Value); Assert.AreEqual("(a+b)*c==(1+2)*3", r.History ); C++ operator overloading allowed for substitution of a simple type with a complex self-tracking entity with an internal tree representation of everything happening with the objects. Now i would like to have the same possibility for NET strings, only instead of variable names i would like to see a stack traces of all the places in code which affected a string. And i want it to work with existing code, and existing compiled assemblies. Also i want all this to hook into visual studio debugger, so i could set a breakpoint, and see everything that happened with a string. Which technology would allow this kind of things? I know it sound like an utopia, but I think visual studio code coverage tools actually do the same kind of job while instrumenting the assemblies.

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• JPA - Real primary key generated ID for references

  - by Val

  I have ~10 classes, each of them, have composite key, consist of 2-4 values. 1 of the classes is a main one (let's call it "Center") and related to other as one-to-one or one-to-many. Thinking about correct way of describing this in JPA I think I need to describe all the primary keys using @Embedded / @PrimaryKey annotations. Question #1: My concern is - does it mean that on the database level I will have # of additional columns in each table referring to the "Center" equal to number of column in "Center" PK? If yes, is it possible to avoid it by using some artificial unique key for references? Could you please give an idea how real PK and the artificial one needs to be described in this case? Note: The reason why I would like to keep the real PK and not just use the unique id as PK is - my application have some data loading functionality from external data sources and sometimes they may return records which I already have in local database. If unique ID will be used as PK - for new records I won't be able to do data update, since the unique ID will not be available for just downloaded ones. At the same time it is normal case scenario for application and it just need to update of insert new records depends on if the real composite primary key matches. Question #2: All of the 10 classes have common field "date" which I described in an abstract class which each of them extends. The "date" itself is never a key, but it always a part of composite key for each class. Composite key is different for each class. To be able to use this field as a part of PK should I describe it in each class or is there any way to use it as is? I experimented with @Embedded and @PrimaryKey annotations and always got an error that eclipselink can't find field described in an abstract class. Thank you in advance! PS. I'm using latest version of eclipselink & H2 database.

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• Help with this compile error

  - by Scott

  I just picked up an old project and I'm not sure what the following error could mean. g++ -o BufferedReader.o -c -g -Wall -std=c++0x -I/usr/include/xmms2 -Ijsoncpp/include/json/ -fopenmp -I/usr/include/ImageMagick -I/usr/include/xmms2 -I/usr/include/libvisual-0.4 -D_GNU_SOURCE=1 -D_REENTRANT -I/usr/include/SDL -DQT_CORE_LIB -DQT_GUI_LIB -DQT_SCRIPT_LIB -DQT_SHARED -I/usr/include/QtCore -I/usr/include/QtGui -I/usr/include/QtScript BufferedReader.cpp In file included from BufferedReader.cpp:23: /usr/include/string.h:36:42: error: missing binary operator before token "(" In file included from /usr/lib/gcc/i686-redhat-linux/4.4.3/../../../../include/c++/4.4.3/cwchar:47, from /usr/lib/gcc/i686-redhat-linux/4.4.3/../../../../include/c++/4.4.3/bits/postypes.h:42, from /usr/lib/gcc/i686-redhat-linux/4.4.3/../../../../include/c++/4.4.3/iosfwd:42, from /usr/lib/gcc/i686-redhat-linux/4.4.3/../../../../include/c++/4.4.3/ios:39, from /usr/lib/gcc/i686-redhat-linux/4.4.3/../../../../include/c++/4.4.3/istream:40, from /usr/lib/gcc/i686-redhat-linux/4.4.3/../../../../include/c++/4.4.3/sstream:39, from BufferedReader.cpp:24: At line 24 of BufferedReader.cpp is #include <string.h>. I've tried it with just <string> but get the same thing. Any clue? Here's the snippet of code from string.h /* Tell the caller that we provide correct C++ prototypes. */ #if defined __cplusplus && __GNUC_PREREQ (4, 4) //line 36 # define __CORRECT_ISO_CPP_STRING_H_PROTO #endif Does that mean __GNUC_PREREQ isn't defined?

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• Creating PHP strings using other variables...works manually, can't figure out how automatically

  - by Matt

  Hello, I'm trying to get a variable to be formed automatically using data pulled from a mysql database. I know the data is being pulled from the database in some form resembling its original form, but that data does not act the same as data that is manually typed and assigned to a string. For example, if a cell in a mysql table says... I said "goodbye" before I left. She also said "goodbye." ...and I manually copy/paste it and add the necessary escapes... $string1 = " I said \"goodbye\" before I left. She also said \"goodbye.\" "; ...that does not equal... $string1 = $mysqlResultArray['specificCellWithQuoteShownAbove'] Interestingly, if I echo both versions of $string1 and view the output, they appear to be exactly the same. But they do not function the same when put through various functions I've created. The functions only work if I do the manual copy/paste method--which is not what I want, obviously. I'm not sure if it has to do with the line breaks or the escapes--or some combination of the two. But while both strings are superficially the same, they are apparently functionally different and I don't know why. So how can I create $string1 without manually copy/pasting the contents from the mysql entry and instead querying for the data and assigning it to $string1 in such a way that it's exactly functionally equivalent as the manual copy/pasted string?

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• "Invalid use of Null" when using Str() with a Null Recordset field, but Str(Null) works fine

  - by Mike Spross

  I'm banging my head against the wall on this one. I was looking at some old database reporting code written in VB6 and case across this line (the code is moving data from a "source" database into a reporting database): rsTarget!VehYear = Trim(Str(rsSource!VehYear)) When rsSource!VehYear is Null, the above line generates an "Invalid use of Null" run-time error. If I break on the above line and type the following in the Immediate pane: ?rsSource!VehYear It outputs Null. Fine, that makes sense. Next, I try to reproduce the error: ?Str(rsSource!VehYear) I get an "Invalid use of Null" error. However, if I type the following into the Immediate window: ?Str(Null) I don't get an error. It simply outputs Null. If I repeat the same experiment with Trim() instead of Str(), everything works fine. ?Trim(rsSource!VehYear) returns Null, as does ?Trim(Null). No run-time errors. So, my question is, how can Str(rsSource!VehYear) possibly throw an "Invalid use of Null" error when Str(Null) does not, when I know that rsSource!VehYear is equal to Null?

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• Iphone xcode simulator crashes when I move up and down on a table row

  - by Frames84

  I can't get my head round this. When the page loads, everything works fine - I can drill up and down, however 'stream' (in the position I have highlighted below) becomes not equal to anything when I pull up and down on the tableview. But the error is only sometimes. Normally it returns key/pairs. If know one can understand above how to you test for // (int)[$VAR count]} key/value pairs in a NSMutableDictionary object - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *FirstLevelCell = @"FirstLevelCell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:FirstLevelCell]; if(cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:FirstLevelCell] autorelease]; } NSInteger row = [indexPath row]; //NSDictionary *stream = (NSDictionary *) [dataList objectAtIndex:row]; NSString *level = self.atLevel; if([level isEqualToString:@"level2"]) { NSMutableDictionary *stream = [[NSMutableArray alloc] init]; stream = (NSMutableDictionary *) [dataList objectAtIndex:row]; // stream value is (int)[$VAR count]} key/value pairs if ([stream valueForKey:@"title"] ) { cell.textLabel.text = [stream valueForKey:@"title"]; cell.textLabel.numberOfLines = 2; cell.textLabel.font =[UIFont systemFontOfSize:10]; NSString *detailText = [stream valueForKey:@"created"]; cell.detailTextLabel.numberOfLines = 2; cell.detailTextLabel.font= [UIFont systemFontOfSize:9]; cell.detailTextLabel.text = detailText; NSString *str = @"http://www.mywebsite.co.uk/images/stories/Cimex.jpg"; NSData *imageURL = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:str]]; UIImage *newsImage = [[UIImage alloc] initWithData:imageURL]; cell.imageView.image = newsImage; [stream release]; } } else { cell.textLabel.text = [dataList objectAtIndex:row]; } return cell; } Thanks for your time

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• C++ STL Map vs Vector speed

  - by sub

  In the interpreter for my experimental programming language I have a symbol table. Each symbol consists of a name and a value (the value can be e.g.: of type string, int, function, etc.). At first I represented the table with a vector and iterated through the symbols checking if the given symbol name fitted. Then I though using a map, in my case map<string,symbol>, would be better than iterating through the vector all the time but: It's a bit hard to explain this part but I'll try. If a variable is retrieved the first time in a program in my language, of course its position in the symbol table has to be found (using vector now). If I would iterate through the vector every time the line gets executed (think of a loop), it would be terribly slow (as it currently is, nearly as slow as microsoft's batch). So I could use a map to retrieve the variable: SymbolTable[ myVar.Name ] But think of the following: If the variable, still using vector, is found the first time, I can store its exact integer position in the vector with it. That means: The next time it is needed, my interpreter knows that it has been "cached" and doesn't search the symbol table for it but does something like SymbolTable.at( myVar.CachedPosition ). Now my (rather hard?) question: Should I use a vector for the symbol table together with caching the position of the variable in the vector? Should I rather use a map? Why? How fast is the [] operator? Should I use something completely different?

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• How to take a collection of bytes and pull typed values out of it?

  - by Pat

  Say I have a collection of bytes var bytes = new byte[] {0, 1, 2, 3, 4, 5, 6, 7}; and I want to pull out a defined value from the bytes as a managed type, e.g. a ushort. What is a simple way to define what types reside at what location in the collection and pull out those values? One (ugly) way is to use System.BitConverter and a Queue or byte[] with an index and simply iterate through, e.g.: int index = 0; ushort first = System.BitConverter.ToUint16(bytes, index); index += 2; // size of a ushort int second = System.BitConverter.ToInt32(bytes, index); index += 4; ... This method gets very, very tedious when you deal with a lot of these structures! I know that there is the System.Runtime.InteropServices.StructLayoutAttribute which allows me to define the locations of types inside a struct or class, but there doesn't seem to be a way to import the collection of bytes into that struct. If I could somehow overlay the struct on the collection of bytes and pull out the values, that would be ideal. E.g. Foo foo = (Foo)bytes; // doesn't work because I'd need to implement the implicit operator ushort first = foo.first; int second = foo.second; ... [StructLayout(LayoutKind.Explicit, Size=FOO_SIZE)] public struct Foo { [FieldOffset(0)] public ushort first; [FieldOffset(2)] public int second; } Any thoughts on how to achieve this?

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• Is there a more efficient way to do this?

  - by garethdn

  I'm hoping there is a better way to the following. I'm creating a jigsaw-type application and this is the current code i'm using: -(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; //location of current touch CGPoint location = [touch locationInView:self.view]; if ([touch view] == img1) { [self animateFirstTouch:img1 withLocation:location]; } else if ([touch view] == img2) { [self animateFirstTouch:img2 withLocation:location]; } else if ([touch view] == img3) { [self animateFirstTouch:img3 withLocation:location]; } else if ([touch view] == img4) { [self animateFirstTouch:img4 withLocation:location]; } else if { ...... ...... } else if ([touch view] == img40) { [self animateFirstTouch:img40 withLocation:location]; return; } } I'm hoping that there is a better, more efficieny way to do this, rather than naming every image. I'm thinking something like, if touch view is equal to a UIImageView, then perform some task. The same for touchesEnded: -(void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; //location of current touch CGPoint location = [touch locationInView:self.view]; if ([touch view] == image1) { [self animateReleaseTouch:image1 withLocation:location]; } else if ([touch view] == image2) { [self animateReleaseTouch:image2 withLocation:location]; } else if ([touch view] == image3) { [self animateReleaseTouch:image3 withLocation:location]; } else if ([touch view] == image4) { [self animateReleaseTouch:image4 withLocation:location]; } else if{ ...... ...... } else if ([touch view] == image40) { [self animateReleaseTouch:image40 withLocation:location]; } return; } Any help please?

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• which is better: a lying copy constructor or a non-standard one?

  - by PaulH

  I have a C++ class that contains a non-copyable handle. The class, however, must have a copy constructor. So, I've implemented one that transfers ownership of the handle to the new object (as below) class Foo { public: Foo() : h_( INVALID_HANDLE_VALUE ) { }; // transfer the handle to the new instance Foo( const Foo& other ) : h_( other.Detach() ) { }; ~Foo() { if( INVALID_HANDLE_VALUE != h_ ) CloseHandle( h_ ); }; // other interesting functions... private: /// disallow assignment const Foo& operator=( const Foo& ); HANDLE Detach() const { HANDLE h = h_; h_ = INVALID_HANDLE_VALUE; return h; }; /// a non-copyable handle mutable HANDLE h_; }; // class Foo My problem is that the standard copy constructor takes a const-reference and I'm modifying that reference. So, I'd like to know which is better (and why): a non-standard copy constructor: Foo( Foo& other ); a copy-constructor that 'lies': Foo( const Foo& other ); Thanks, PaulH

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• optimize output value using a class and public member

  - by wiso

  Suppose you have a function, and you call it a lot of times, every time the function return a big object. I've optimized the problem using a functor that return void, and store the returning value in a public member: #include <vector> const int N = 100; std::vector<double> fun(const std::vector<double> & v, const int n) { std::vector<double> output = v; output[n] *= output[n]; return output; } class F { public: F() : output(N) {}; std::vector<double> output; void operator()(const std::vector<double> & v, const int n) { output = v; output[n] *= n; } }; int main() { std::vector<double> start(N,10.); std::vector<double> end(N); double a; // first solution for (unsigned long int i = 0; i != 10000000; ++i) a = fun(start, 2)[3]; // second solution F f; for (unsigned long int i = 0; i != 10000000; ++i) { f(start, 2); a = f.output[3]; } } Yes, I can use inline or optimize in an other way this problem, but here I want to stress on this problem: with the functor I declare and construct the output variable output only one time, using the function I do that every time it is called. The second solution is two time faster than the first with g++ -O1 or g++ -O2. What do you think about it, is it an ugly optimization?

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• Android 2.1 How to get Phone Numbers of contacts.

  - by Brandon Delany

  Hi, I am new to Android and have been working on an app that needs to get all of the user's contact's phone numbers. Apparently the code I have does not work with the 2.1 SDK. So far here is the code I am using: String[] projection = new String[] { Phone.NUMBER }; Cursor c = managedQuery( Phone.CONTENT_URI, projection, null, null, null ); int colIndex = -1; try { colIndex = c.getColumnIndexOrThrow( Phone.NUMBER ); } catch( Exception e ) { print( e.getMessage() ); } print( "Column Index = " + colIndex ); //count is equal to 3 for( int i = 0; i < count; i++ ){ try { print( c.getString( 2 ) ); //the 2 used to be colIndex } catch ( Exception e ) { print( e.getMessage() ); } } It seems that no matter what I pass into c.getString() it keeps telling me that I passed in -1. But I even hardcoded the 2, and it says the same thing. Any help would be much appreciated.

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• How do you calculate div and mod of floating point numbers?

  - by boost

  In Perl, the % operator seems to assume integers. For instance: sub foo { my $n1 = shift; my $n2 = shift; print "perl's mod=" . $n1 % $n2, "\n"; my $res = $n1 / $n2; my $t = int($res); print "my div=$t", "\n"; $res = $res - $t; $res = $res * $n2; print "my mod=" . $res . "\n\n"; } foo( 3044.952963, 7.1 ); foo( 3044.952963, -7.1 ); foo( -3044.952963, 7.1 ); foo( -3044.952963, -7.1 ); gives perl's mod=6 my div=428 my mod=6.15296300000033 perl's mod=-1 my div=-428 my mod=6.15296300000033 perl's mod=1 my div=-428 my mod=-6.15296300000033 perl's mod=-6 my div=428 my mod=-6.15296300000033 Now as you can see, I've come up with a "solution" already for calculating div and mod. However, what I don't understand is what effect the sign of each argument should have on the result. Wouldn't the div always be positive, being the number of times n2 fits into n1? How's the arithmetic supposed to work in this situation?

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