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  • What was that tutorial on pointers?

    - by pecker
    Hello, I once read a tutorial/article on Pointers somewhere. It was not a general tutorial but it explained how to clearly understand the complex & confusing pointers (especially like the ones that are usually asked in interview). It was more like http://www.codeweblog.com/right-left-rule-complex-pointer-analysis/ I'm unable to find it. Could any one post it here. PS: I did tried to google it but couldn't find. I'm asking it here because I thought it was popular.

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  • what is this 'map' mean..in django

    - by zjm1126
    this is the code: def create(request, form_class=MapForm, template_name="maps/create.html"): map_form = form_class(request.POST or None) if map_form.is_valid(): map = map_form.save(commit=False) and the map_form is : class MapForm(forms.ModelForm): slug = forms.SlugField(max_length=20, help_text = _("a short version of the name consisting only of letters, numbers, underscores and hyphens."), #error_message = _("This value must contain only letters, numbers, underscores and hyphens.")) ) def clean_slug(self): if Map.objects.filter(slug__iexact=self.cleaned_data["slug"]).count() > 0: raise forms.ValidationError(_("A Map already exists with that slug.")) return self.cleaned_data["slug"].lower() def clean_name(self): if Map.objects.filter(name__iexact=self.cleaned_data["name"]).count() > 0: raise forms.ValidationError(_("A Map already exists with that name.")) return self.cleaned_data["name"] class Meta: model = Map fields = ('name', 'slug', 'description')

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  • Queue-like data structure with fast search and insertion

    - by Max
    I need a datastructure with the following properties: It contains integer numbers, no duplicates. After it reaches the maximal size the first element is removed. So if the capacity is 3, then this is how it would look when putting in it sequential numbers: {}, {1}, {1, 2}, {1, 2, 3}, {2, 3, 4}, {3, 4, 5} etc. Only two operations are needed: inserting a number into this container (INSERT) and checking if the number is already in the container (EXISTS). The number of EXISTS operations is expected to be approximately 2 * number of INSERT operations. I need these operations to be as fast as possible. What would be the fastest data structure or combination of data structures for this scenario?

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  • Multiplying matrices: error: expected primary-expression before 'struct'

    - by justin
    I am trying to write a program that is supposed to multiply matrices using threads. I am supposed to fill the matrices using random numbers in a thread. I am compiling in g++ and using PTHREADS. I have also created a struct to pass the data from my command line input to the thread so it can generate the matrix of random numbers. The sizes of the two matrices are also passed in the command line as well. I keep getting: main.cpp:7: error: expected primary-expression before 'struct' my code @ line 7 =: struct a{ int Arow; int Acol; int low; int high; }; My inpust are : Sizes of two matrices ( 4 arguments) high and low ranges in which o generate the random numbers between. Complete code: [headers] using namespace std; void *matrixACreate(struct *); void *status; int main(int argc, char * argv[]) { int Arow = atoi(argv[1]); // Matrix A int Acol = atoi(argv[2]); // WxX int Brow = atoi(argv[3]); // Matrix B int Bcol = atoi(argv[4]); // XxZ, int low = atoi(argv[5]); // Range low int high = atoi(argv[6]); struct a{ int Arow; // Matrix A int Acol; // WxX int low; // Range low int high; }; pthread_t matrixAthread; //pthread_t matrixBthread; pthread_t runner; int error, retValue; if (Acol != Brow) { cout << " This matrix cannot be multiplied. FAIL" << endl; return 0; } error = pthread_create(&matrixAthread, NULL, matrixACreate, struct *a); //error = pthread_create(&matrixAthread, NULL, matrixBCreate, sendB); retValue = pthread_join(matrixAthread, &status); //retValue = pthread_join(matrixBthread, &status); return 0; } void matrixACreate(struct * a) { struct a *data = (struct a *) malloc(sizeof(struct a)); data->Arow = Arow; data->Acol = Acol; data->low = low; data->high = high; int range = ((high - low) + 1); cout << Arow << endl<< Acol << endl; }// just trying to print to see if I am in the thread

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  • R: simple and short if clauses for combind statements

    - by jorgusch
    Hello, TRUE/FALSE if clauses are easily and quickly done in R. However, if the argument gets more complex, it also gets ugly very soon. For instance: I might want to execute different operations for a row(foo) dependent on the value in one cell (foo[1]). Let the intervals be 0:39 and 40:59 and 60:100 Something like does not exit: (if foo[1] "in" 40:60){... In fact, I only see ways of at least two if clauses and two else statements and the action for the first interval somewhere at the bottom of the code. With more intervals(or any other condition) it is getting more complex. Is there a best practice (for this purpose or others) with a simple construction and nice design to read? Thanks a lot!

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  • How to Select Multiple Records from Multiple Tables at Once - SQL Server/C#/.NET/T-SQL

    - by peace
    I have two tables Customer and CustomerPhone. Customer usually has multiple phone numbers, so when i run select statement on customer 101, i will get multiple records due to the multiple phone numbers. As you see below all the "Phone" and "Fax" field belongs to CustomerPhone table. These are considered as two records in the CustomerPhone table whereas the rest of fields relate to Customer table which is a single record. What should i do to fill Phone and Fax field in this case? Should i run select statement on CustomerPhone first and then run select statement on Customer?

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  • Math Looping Between Min and Max Using Mod?

    - by TheDarkIn1978
    i'm attempting to build a tiny (or perhaps not so tiny) formula that will contain numbers between a set min and max, but also loop these numbers so they are not clipped if they are outside of the range. so far, this is what i have. min1 = 10 max1 = 90 val1 = 92 //will make 12, which is what i want since it loops formula: min(max(min1,min(val1,max1)),mod(val1,max1)+min1) however, i'd like it to loop the other direction also, so that if val1 is 5, which is -5 outside of min1, it will become 85. another problem i'm running into is that max1 % max1 != max1 as i want it to, since the max is part of the range trying to be clear, here are some examples of desired output based on a range with looping min1 = 10 max1 = 90 ---------------------------------------------- val1 = 30 //within range: stays as 30 val1 = 90 //within range: stays as 90 val1 = -6 //below range: loops to becomes 84 val1 = 98 //above range: loops to becomes 18 i'd like not to resort to using a series of if/else statements, but one would be fine if it's absolutely required. is that even possible?

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  • cutting a text file into multiple parts in emacs

    - by Gaurish Telang
    Hi I am using the GNU-Emacs-23 editor. I have this huge text file containing about 10,000 lines which I want to chop into multiple files. Using the mouse to select the required text to paste in another file is the really painful. Also this is prone to errors too. If I want to divide the text file according to the line numbers into say 4 file where first file:lines 1-2500 second file:lines 2500-5000 third file :lines 5000-7500 fourth file: lines: 7500-10000 how do I do this? At the very least, is there any efficient way to copy large regions of the file just by specifying line numbers

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  • compute mean in python for a generator

    - by nmaxwell
    Hi, I'm doing some statistics work, I have a (large) collection of random numbers to compute the mean of, I'd like to work with generators, because I just need to compute the mean, so I don't need to store the numbers. The problem is that numpy.mean breaks if you pass it a generator. I can write a simple function to do what I want, but I'm wondering if there's a proper, built-in way to do this? It would be nice if I could say "sum(values)/len(values)", but len doesn't work for genetators, and sum already consumed values. here's an example: import numpy def my_mean(values): n = 0 Sum = 0.0 try: while True: Sum += next(values) n += 1 except StopIteration: pass return float(Sum)/n X = [k for k in range(1,7)] Y = (k for k in range(1,7)) print numpy.mean(X) print my_mean(Y) these both give the same, correct, answer, buy my_mean doesn't work for lists, and numpy.mean doesn't work for generators. I really like the idea of working with generators, but details like this seem to spoil things. thanks for any help -nick

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  • Get a list of Android phone contacts only on Eclair and above?

    - by Rob Kent
    I want to show the user a flattened pick list of all their contacts phone numbers and it must work from versions 1.6 up. I have read the related questions on SO and the Android documentation for Eclair (http://developer.android.com/resources/articles/contacts.html#legacy). The problem is, even splitting my code into a factory class and specific implementations does not work for me because using Contacts.CONTENT_URI only shows contacts not individual numbers. What I need is this for version 1.6 Intent intent = new Intent(Intent.ACTION_PICK, Phones.CONTENT_URI); startActivityForResult(intent, REQUEST_PICK_CONTACT); And the equivalent for 2.0 and above. Even if I get their example to work, by building against the 2.1 API am I not stopping my app being visible on the Market to users with earlier versions of the OS? I can't launch it against a 1.6 emulator, for example.

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  • Vehicle Make/Model and Parts Database

    - by Jas Panesar
    I am looking to see if there is a web based service I can either access programmatically to access teh following information, or a database I could purchase or interface with. I am looking to see if there are databases out there for: 1) Vehicle makes and models -- I recall something being out there in the $500/yr range 2) Vehicle Part Numbers - A database of car part numbers that is maintained and updated for a yearly subscription. I had read something similar about databases being purchased for other industries on SO.. so I figure this is fair game. Thanks in advance!

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  • How to persist non-trivial fields in Play Framework

    - by AlexR
    I am trying to persist complex objects using Ebeans in Play Framework (2.03). In particular, I've created a class that contains a field of type weka.classifier.Classifier (Weka is a popular machine learning library - see http://weka.sourceforge.net/doc/weka/classifiers/Classifier.html). Classifier implements Serializeable so I hoped that I can get away with something like @Entity @Table(name = "classifiers") public class ClassifierData extends Model { @Id public Long id; public Classifier classifier; } However, the Evolutions script suggests the following database structure: create table classifiers ( id bigint auto_increment not null, constraint pk_classifiers primary key (id)) ) In other words, it ignores the field of type Classifier. (The database is MySQL if it makes any difference) What should I do to store complex serializeable objects using Ebean/Evolutions/PlayFramework?

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  • Integers in JavaScript

    - by muntoo
    I'm a beginner to Javascript so forgive me if I sound dumb because I learned some Javascript from W3Fools (which are really difficult tutorials - they don't explain anything I want to know, but everything I probably can guess from my experience with C++). I may be switching over to MDN, but if you can recommend any other tutorials, that be great. Anyways, so here's my question: I just read a few lines of this, and apparently: Numbers in JavaScript are "double-precision 64-bit format IEEE 754 values", according to the spec. This has some interesting consequences. There's no such thing as an integer in JavaScript, so you have to be a little careful with your arithmetic if you're used to math in C or Java. I've already seen that there are few of the data types (for variables) I'm used to from C++. But I didn't expect all numbers to automatically be floats. Isn't there any way to use integers, not float? Will a future version of JavaScript support ints?

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  • Unit Testing User Interface. What is an effective way ?

    - by pierocampanelli
    I have an accounting & payroll client/server application where there are several input form with complex data validation rules. I am finding an effective way to perform unit testing of user interface. For complex validation rules I mean: "Disable button X if I Insert a value in textfield Y" "Enable a combobox if I insert a value in a textfield" ...... ...... Most promising pattern i have found is suggested by M. Fowler (http://martinfowler.com/eaaDev/ModelViewPresenter.html). Have you any experience about Unit Testing of User Interface? As technology stack I am using: .NET 3.5 & Windows Forms Widget Library.

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  • How to create updateable panel using AjaxLink of Wicket?

    - by Arne
    I try to realize a link (in fact many links) that update a table in an website using an AjaxLink of Wicket. But I fail, the table is never updated (I have "setOutputMarkupId(true)" and call "addComponent", but there must be something other thats wrong). How can I realize a panel with a number of links and a table that displays dynamic data, dependent on the link clicked? Can someone give an example (Maybe two links, when the first one is clicked the table displays two random numbers from 1-10, when the second is clicked the table displays random numbers from 1-100)? Without reloading the entire page, but only the html for the table?

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  • How to get a Javascript routine to NOT act if it's in a text box?

    - by talkingnews
    I've got a simple page, and in that page runs a simple jquery keypress routine to catch clicks of the numbers 1 to 9 (has to be that to pass RNIB accessibility test). And in that page is a form, which can have numbers entered as part of a postcode. http://find.talking-newspapers.co.uk/result.php?addressInput=kingston Scroll to the bottom, try typing 8 or 9 for example. The text is entered, but it also acts on the keypress. Expected, but not good. I'm aware of various things like document.getElementById, but I can't figure out how to put these together to ensure that while the cursor is in the text input box, it doesn't act out the keypress catcher.

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  • Standard (cross-platform) way for bit manipulation

    - by Kiril Kirov
    As are are different binary representation of the numbers (for example, take big/little endian), is this cross-platform: some_unsigned_type variable = some_number; // set n-th bit, starting from 1, // right-to-left (least significant-to most significant) variable |= ( 1 << ( n - 1 ) ); // clear the same bit: variable &= ~( 1 << ( n - 1 ) ); In other words, does the compiler always take care of the different binary representation of the unsigned numbers, or it's platform-specific? And what if variable is signed integral type (for example, int) and its value is zero positive negative? What does the Standard say about this? P.S. And, yes, I'm interesting in both - C and C++, please don't tell me they are different languages, because I know this :) I can paste real example, if needed, but the post will become too long

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  • TextBoxWatermarkExtender and Custom validator problem

    - by Mac
    i have two textboxes one for phone and one for email for phone textbox i have used textbox watermark extender and a filtered textbox extender provided in ajax extension toolkit as a water mark extender text iam displaying only numbers are allowed. the problem is that on client side validation of two textboxes by custom validator iam checking function ValidatePhoneEmail(source, args) { var txtEmail = $('#<%= txtEmail.ClientID %'); var txtPhone = $('#<%= txtPhone.ClientID %>'); if (txtEmail.focus().val().trim() != '' || txtPhone.focus().val().trim() != '') { args.isValid = true; } else { args.isValid = false; } } and the problem is phone textbox is not empty as it contains text "Only Numbers" so it always return false what to do..?

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  • Programming language for fast calculations with big integers

    - by sub
    I'm doing Project Euler problems at the moment and I can solve most of them using my own programming language which uses direct C++ integers (so they are bound to 2^32 on my machine). However, at times there are problems which require me to work with very high numbers, I can't do that with native integers. So I implemented a BigInt library in my language which unfortunately gets extremely slow at times. Is there a programming language suitable for very efficient handling of big numbers? I mean that I want to do the things I could do in other programming languages with it (variables, loops, etc.), but in a faster way. If you have got tips for workarounds of the 2^32 limit in my language/C++/other languages, please tell me too!

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  • Help with bugs in a C code

    - by Yanki Twizzy
    This C code is giving me some unpredictable results. The program is meant to collect 6 nos and print out the max, position of the max no and the average. It's supposed to have only 3 functions - input, max_avr_pos and output for doing what the code is supposed to do but I am getting unpredictable results. Please what could be the problem #include <stdio.h> #include <stdlib.h> #include <conio.h> void input_vals(int arrnum[]); void max_ave_val(int arrnum1[],double *average,int *maxval,int *position); void print_output(double *average1,int *maxval1,int *position1); int main(void) { int arrnum[6],maxval2,position2; double average2; input_vals(arrnum); max_ave_val(arrnum,&average2,&maxval2,&position2); print_output(&average2,&maxval2,&position2); _getche(); return 0; } void input_vals(int arrnum[]) { int count; printf("\n Please enter six numbers\n"); for(count=0;count<6;count++) { scanf("%d",&arrnum[count]); } } void max_ave_val(int arrnum1[],double *average,int *maxval,int *position) { int total=0; int cnt,cnt1,cnt2,limit,maxval2,post; limit=6; /* finding the max value*/ for(cnt=0;cnt<limit-1;cnt++) for(cnt1=limit-1;cnt1>cnt;--cnt1) { if(arrnum1[cnt1-1]>arrnum1[cnt1]) { maxval2=arrnum1[cnt-1]; post=(cnt-1)+1; } else { maxval2=arrnum1[cnt1]; post=cnt1+1; } } *maxval=maxval2; *position=post; /* solving for total */ for(cnt2=0;cnt2<limit;cnt2++); { total=total+arrnum1[cnt2]; } *average=total/limit; } void print_output(double *average1,int *maxval1,int *position1) { printf("\n value of the highest of the numbers is %d\n",*maxval1); printf("\n the average of all the numbers is %g\n",*average1); printf("\n the postion of the highest number in the list is %d\n",*position1); }

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  • Is there a more correct type for passing in the file path and file name to a method

    - by Rihan Meij
    Hi What I mean by this question is, when you need to store or pass a URL around, using a string is probably a bad practice, and a better approach would be to use a URI type. However it is so easy to make complex things more complex and bloated. So if I am going to be writing to a file on disk, do I pass it a string, as the file name and file path, or is there a better type that will be better suited to the requirement? This code seems to be clunky, and error prone? I would also need to do a whole bit of checking if it is a valid file name, if the string contains data and the list goes on. private void SaveFile(string fileNameAndPath) { //The normal stuff to save the file }

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  • iPhone simple commercial barcode reader via camera

    - by user347635
    Hey all, I've done some iPhone programming (safely midlevel) and now a requirement has come up for us to write a barcode reader that uses the iPhone camera. This is not for shopping or the general public but will be for internal use. My first thought was to simply programatically take a picture, upload it to server, and have a web service or something similar handle the heavy lifting of extracting the numbers out of the bar code. However I recently installed some apps already available on the iPhone that read bar codes, refer you to shopping sites, etc. and they seem to use the video camera to identify barcodes and extract the numbers. Does anyone know how this is being done or could point me to some open source or sample code?

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  • Effective Data Validation

    - by John Conde
    What's an effective way to handle data validation, say, from a form submission? Originally I had a bunch of if statements that checked each value and collected invalid values in an array for later retrieval (and listing). // Store errors here $errors = array(); // Hypothetical check if a string is alphanumeric if (!preg_match('/^[a-z\d]+$/i', $fieldvalue)) { $errors[$fieldname] = 'Please only use letters and numbers for your street address'; } // etc... What I did next was create a class that handles various data validation scenarios and store the results in an internal array. After data validation was complete I would check to see if any errors occurred and handle accordingly: class Validation { private $errorList = array(); public function isAlphaNumeric($string, $field, $msg = '') { if (!preg_match('/^[a-z\d]+$/i', $string)) { $this->errorList[$field] = $msg; } } // more methods here public function creditCard($cardNumber, $field, $msg = '') { // Validate credit card number } // more methods here public function hasErrors() { return count($this->errorList); } } /* Client code */ $validate = new Validation(); $validate->isAlphaNumeric($fieldvalue1, $fieldname1, 'Please only use letters and numbers for your street address'); $validate->creditCard($fieldvalue2, $fieldname2, 'Please enter a valid credit card number'); if ($validate->hasErrors()) { // Handle as appropriate } Naturally it didn't take long before this class became bloated with the virtually unlimited types of data to be validated. What I'm doing now is using decorators to separate the different types of data into their own classes and call them only when needed leaving generic validations (i.e. isAlphaNumeric()) in the base class: class Validation { private $errorList = array(); public function isAlphaNumeric($string, $field, $msg = '') { if (!preg_match('/^[a-z\d]+$/i', $string)) { $this->errorList[$field] = $msg; } } // more generic methods here public function setError($field, $msg = '') { $this->errorList[$field] = $msg; } public function hasErrors() { return count($this->errorList); } } class ValidationCreditCard { protected $validate; public function __construct(Validation $validate) { $this->validate = $validate; } public function creditCard($cardNumber, $field, $msg = '') { // Do validation // ... // if there is an error $this->validate->setError($field, $msg); } // more methods here } /* Client code */ $validate = new Validation(); $validate->isAlphaNumeric($fieldvalue, $fieldname, 'Please only use letters and numbers for your street address'); $validateCC = new ValidationCreditCard($validate); $validateCC->creditCard($fieldvalue2, $fieldname2, 'Please enter a valid credit card number'); if ($validate->hasErrors()) { // Handle as appropriate } Am I on the right track? Or did I just complicate data validation more then I needed to?

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