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• how to set and access variable values from another classess

  - by BittenApple

  I am modifying QuartzDemo example app and want to do set and read values of integer type variables in other classes which are already included. For example, in MainViewController.m I want to set a numeric value (simple numbers from 1-100) to a variable which is then going to be called (read) in file QuartzImages.m. Question is how to define variable properly, set and access (read) the value. I am a beginner with Obj C and iPhone SDK in general and have some experience with Delphi and VB but this doesn't help at all :) Thank you, whoever and wherever you are, person who will take me out of this endless googling loop.

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• What is the cost of memory access?

  - by Jurily

  We like to think that a memory access is fast and constant, but on modern architectures/OSes, that's not necessarily true. Consider the following C code: int i = 34; int *p = &i; // do something that may or may not involve i and p {...} // 3 days later: *p = 643; What is the estimated cost of this last assignment in CPU instructions, if i is in L1 cache, i is in L2 cache, i is in L3 cache, i is in RAM proper, i is paged out to an SSD disk, i is paged out to a traditional disk? Where else can i be? Of course the numbers are not absolute, but I'm only interested in orders of magnitude. I tried searching the webs, but Google did not bless me this time.

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• Strange hex formatting in NSString

  - by pseudopeach

  Try this: unsigned long long int N; = 23229877463LL; NSString* s = [NSString stringWithFormat:@"dec:%qi, hex:%qX",N,N]; NSLog(@"output: %@",s); output: dec:23229877460, hex:689BCCD400000005 What's up with the 00000005??? In mySQL, hex(23229877460) = 5689BCCD4. Also, every other language seems to do this correctly. A 16 digit long hex is like 4 gazillion (16^16), right? How can I get objective-c to format hex numbers that other languages can understand?

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• how do I check if a c++ string is an int?

  - by user342231

  when I use getline, I would input a bunch of strings or numbers, but I only want the while loop to output the "word" if it is not a number. so is there any way to check if "word" is a number or not, I know I could use atoi() for c-strings but how about for strings of the string class int main () { stringstream ss (stringstream::in | stringstream::out); string word; string str; getline(cin,str); ss<<str; while(ss>>word) { //if( ) cout<<word<<endl; } }

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• Which database should I use for best performance

  - by _simon_

  Hello, I am working in Visual Studio 2005, .NET 2.0. I need to write an application, which listens on COM port and saves incoming data to a database. Main feature: save incoming data (series of 13-digits numbers), if this number allready exists, then mark it as double. For example, there could be these records in database: 0000000000001 OK 0000000000002 OK 0000000000002 Double 0000000000003 OK 0000000000004 OK I could use SQL database, but I don't know if it is fast enough... Database should be able to store up to 10.000.000 records and write up to 100 records per minute (so it needs to check 100 times per minute if this record allready exists). Which database should I use? Maybe the whole database would need to be in RAM. Where could I learn more about this? Thanks

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• How to insert into std::map.

  - by Knowing me knowing you

  In code below: map<string,vector<int>> create(ifstream& in, const vector<string>& vec) { /*holds string and line numbers into which each string appears*/ typedef map<string,vector<int>> myMap; typedef vector<string>::const_iterator const_iter; myMap result; string tmp; unsigned int lineCounter = 0; while(std::getline(in,tmp)) { const_iter beg = vec.begin(); const_iter end = vec.end(); while (beg < end) { if ( tmp.find(*beg) != string::npos) { result[*beg].push_back(lineCounter);//THIS IS THE LINE I'M ASKING FOR } ++beg; } ++lineCounter; } return result; } How should I do it (check line commented in code) if I want to use insert method of map instead of using operator[]? Thank you.

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• Python - a clean approach to this problem?

  - by Seafoid

  Hi, I am having trouble picking the best data structure for solving a problem. The problem is as below: I have a nested list of identity codes where the sublists are of varying length. li = [['abc', 'ghi', 'lmn'], ['kop'], ['hgi', 'ghy']] I have a file with two entries on each line; an identity code and a number. abc 2.93 ghi 3.87 lmn 5.96 Each sublist represents a cluster. I wish to select the i.d. from each sublist with the highest number associated with it, append that i.d. to a new list and ultimately write it to a new file. What data structure should the file with numbers be read in as? Also, how would you iterate over said data structure to return the i.d. with the highest number that matches the i.d. within a sublist? Thanks, S :-)

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• How to check input text into web form? java script

  - by butteff

  how to check input text before POST operation? it must be numbers only <form method="post" action="credit.php"> ????? ???????: <input type="text" name="sum"> <br /> ?????? ?????: <input type="text" name="pv"> <br /> ????: <input type="text" name="srok"> <br /> ?????????? ??????: <input type="text" name="percent"> <br /> <input type="submit"> </form> sorry for my bad english.

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• Changing floating point behavior in Python to Numpy style.

  - by Tristan

  Is there a way to make Python floating point numbers follow numpy's rules regarding +/- Inf and NaN? For instance, making 1.0/0.0 = Inf. >>> from numpy import * >>> ones(1)/0 array([ Inf]) >>> 1.0/0.0 Traceback (most recent call last): File "<stdin>", line 1, in <module> ZeroDivisionError: float division Numpy's divide function divide(1.0,0.0)=Inf however it is not clear if it can be used similar to from __future__ import division.

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• How to provide an API client with 1,000,000 database results?

  - by Chris Dutrow

  What is a good way to provide an API client with 1,000,000 database results? We are cureently using PostgreSQL. A few suggested methods: Paging using Cursors Paging using random numbers ( Add "GREATER THAN ORDER BY " to each query ) Save information to a file and let the client download it Iterate through results, then POST the data to the client server Return only keys to the client, then let the client request the objects from Cloud files like Amazon S3 (still may require paging just to get the file names ). What haven't I thought of that is stupidly simple and way better than any of these options?

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• Pagination using Ajax in jquery Datatables

  - by kshtjsnghl

  I am using dataTables plugin for a table on a page I am working on. Its basically fetching rows through an ajax call and in this ajax call, I send the search params that the user selects and the page number required. I need the Next, Previous, First and Last buttons to also fire the same ajax call, but with different page numbers, as the back-end interceptor depends on the page number. This api call would return total no. of rows(say 1000) belonging for these search params and the rows with the page size( say 50). Is there any way, I can use data table to do this?

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• SQL Server concurrency and generated sequence

  - by Goyuix

  I need a sequence of numbers for an application, and I am hoping to leverage the abilities of SQL Server to do it. I have created the following table and procedure (in SQL Server 2005): CREATE TABLE sequences ( seq_name varchar(50) NOT NULL, seq_value int NOT NULL ) CREATE PROCEDURE nextval @seq_name varchar(50) AS BEGIN DECLARE @seq_value INT SET @seq_value = -1 UPDATE sequences SET @seq_value = seq_value = seq_value + 1 WHERE seq_name = @seq_name RETURN @seq_value END I am a little concerned that without locking the table/row another request could happen concurrently and end up returning the same number to another thread or client. This would be very bad obviously. Is this design safe in this regard? Is there something I can add that would add the necessary locking to make it safe? Note: I am aware of IDENTITY inserts in SQL Server - and that is not what I am looking for this in particular case. Specifically, I don't want to be inserting/deleting rows. This is basically to have a central table that manages the sequential number generator for a bunch of sequences.

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• What is the best way to make a game timer in Actionscript 3?

  - by Nuthman

  I have built an online game system that depends on a timer that records how long it took a player to complete a challenge. It needs to be accurate to the millisecond. Their time is stored in a SQL database. The problem is that when I use the Timer class, some players are ending up getting scores in the database of less than a second. (which is impossible, as most challenges would take at least 11 seconds to complete even in a perfect situation.) What I have found is that if a player has too many browser windows open, and/or a slow computer, the flash game slows down actually affecting the timer speed itself. The timer is 'spinning' on screen so you can physically see the numbers slowing down. It is frustrating that I cannot just open a second thread or do something to allow flash to keep accurate time regardless of whatever else is going on in the program. Any ideas?

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• Building a financial app with Django

  - by mfalcon

  Hi guys, I'm building an app for a small business so I've to work with currencies, decimal numbers, etc... My goal is to create something like pulseapp.com. I've searched for opensource projects to look and the only thing I had found was django-cashflow. This app uses python-money. I've read some of the code and the ways it's coded seems a bit weird to me and it's not fully complete. Is the app worth to take a deep look? Does anyone know about another similar app? Is the task difficult or a begginer like me could find a way to code it himself?

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• Millionth number in the serie 2 3 4 6 9 13 19 28 42 63 ... ?

  - by HH

  It takes about minute to achieve 3000 in my comp but I need to know the millionth number in the serie. The definition is recursive so I cannot see any shortcuts except to calculate everything before the millionth number. How can you fast calculate millionth number in the serie? Serie Def n_{i+1} = \floor{ 3/2 * n_{i} } and n_{0}=2. Interestingly, only one site list the serie according to Goolge: this one. Too slow Bash code #!/bin/bash function serie { n=$( echo "3/2*$n" | bc -l | tr '\n' ' ' | sed -e 's@\\@@g' -e 's@ @@g' ); # bc gives \ at very large numbers, sed-tr for it n=$( echo $n/1 | bc ) #DUMMY FLOOR func } n=2 nth=1 while [ true ]; #$nth -lt 500 ]; do serie $n # n gets new value in the function throught global value echo $nth $n nth=$( echo $nth + 1 | bc ) #n++ done

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• matlab: putting a circled number onto a graph

  - by Jason S

  I want to put a circled number on a graph as a marker near (but not on) a point. Sounds easy, but I also want to be invariant of zoom/aspect ratio changes. Because of this invariant, I can't draw a circle as a line object (without redrawing it upon rescale); if I use a circle marker, I'd have to adjust its offset upon rescale. The simplest approach I can think of is to use the Unicode or Wingdings characters ① ② ③ etc. in a string for the text() function. But unicode doesn't seem to work right, and the following sample only works with ① and not for the other numbers (which yield rectangle boxes): works: clf; text(0.5,0.5,char(129),'FontName','WingDings') doesn't work (should be a circled 2): clf; text(0.5,0.5,char(130),'FontName','WingDings') What gives, and can anyone suggest a workaround?

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• Multiple repositories or single repository with branches?

  - by Goro

  I have been working on a project for some time, and it has branched off into several different versions. All versions have some common code base, and each version has specific functionality that is unique, and each version will need to be supported individually. What SVN structure would you recommend? Right now I am using a separate repository for each project, but the downside of that is that it is impractical for large number of products. The downside of using a single repository with branches is that it would add revision numbers to every branch whether anything was committed, regardless from which branch. What setup do you/would you use in this situation?

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• Python code to do csv file row entries comparison operations and count the number of times row value

  - by Venomancer

  have an excel based CSV file with two columns (or rows, Pythonically) that I am working on. What I need to do is to perform some operations so that I can compare the two data entries in each 'row'. To be more precise, one column has constant numbers all the way down, whereas the other column has varying values. So I need to count the number of times the varying column data entry values crosses the constant value on the other column. For example, fro the csv file i have two columns: Varying Column; Constant Column 24 25 26 25 crossed 27 25 26 25 25.5 25 23 25 crossed 26 25 crossed Thus, the varying column data entries have crossed 25 three times. I need to generate a code that can count the number of the crosses. Please do help out, Thanks.

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• Unique number identifier generation

  - by xwrs

  I have to create logic for generation unique number identifier for records in database. id, generated in database is a separate column. At this moment, when user calls "create record" action, I save new record, get its database id, generate record number using this id, then put it to the edit form. Using this way means that all entity fields should be nullable to save record to database. I don't like this way. I know that should be better way. Is there a better practice to generate unique number identifier? What is possibility of generating non-unique random numbers? Thank you

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• Generating Fibonacci series in F#

  - by photo_tom

  I'm just starting to learn F# using VS2010 and below is my first attempt at generating the Fibonacci series. What I'm trying to do is to build a list of all numbers less than 400. let fabList = let l = [1;2;] let mutable a = 1 let mutable b = 2 while l.Tail < 400 do let c = a + b l.Add(c) let a = b let b = c My first problem is that on the last statement, I'm getting an error message "Incomplete structured construct at or before this point in expression" on the last line. I don't understand what I'm doing wrong here. While this seems to be an obvious way to build the list in a fairly efficient way (from a c++/C# programmer), from what little I know of f#, this doesn't seem to feel to be the right way to do the program. Am I correct in this feeling?

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• For each element A[i] of array A, find the closest j such that A[j] > A[i]

  - by SamH

  Hi everyone. Given : An array A[1..n] of real numbers. Goal : An array D[1..n] such that D[i] = min{ distance(i,j) : A[j] > A[i] } or some default value (like 0) when there is no higher-valued element. I would really like to use Euclidean distance here. Example : A = [-1.35, 3.03, 0.73, -0.06, 0.71, -0.21, -0.12, 1.49, 1.41, 1.42] D = [1, 0, 1, 1, 2, 1, 1, 6, 1, 2] Is there any way to beat the obvious O(n^2) solution? The only progress I've made so far is that D[i] = 1 whenever A[i] is not a local maxima. I've been thinking a lot and have come up with NOTHING. I hope to eventually extend this to 2D (so A and D are matrices).

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• R - Subsetting XTS via Time and Which

  - by user2844947

  Currently, I have a XTS, called Data, which contains a Date, and two value columns which are numbers. I would like to get a single number as output and which would be the mean of Value1 in the time period from a point where Value2 < mean(Value2) and going forward 14 data points, weeks in this particular data set. In order to get the dates where Value2 < mean(Value2), I wrote the below code Data[which(Data$Value2 < mean(Data$Value2)),"Date"] However, I am not sure how to get the mean of Value1 in the period, going 14 days forward from each of the resultant dates from the above code.

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• Filtering Data in a Text File with Python

  - by YAS

  I'm new to Python (like Zygote new), and it's just to supplement another program but what I need is I have a text file that's a group of items for a game and it is formatted so: [1] Name=Blah Faction=Blahdiddly Cost=1000 [2] Name=Meh Faction=MehMeh Cost=2000 [3] Name=Lollypop Faction=Blahdiddly Cost=100 And I need to be able to find out what groups (the numbers in brackets) have matching values. So if I search Faction=Blahdiddly Group 1 & 3 will come up. I unfortunately have NO idea how to do this. Can anyone help?

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• Moving UITableView row to top of list when selected

  - by Max Kilgore

  I am sure this is an easy thing to do. I am very new to objective C (picked up a job the boss was going to outsource) and could use all the help I can get. Just point me in the right direction here. Basically what I want to set up is this: I have a list of phone numbers that expands to as many rows as needed. I have no problem populating and the list works fine, but I would like for all of the recently selected items in the list to be more easily accessible at the top. So, whenever the user "didSelectRowAtIndexPath", I would like the row to move to the top. I just KNOW this is super simple... but I haven't found the solution yet. No hurry. I am just trying to figure things out on my own. Thanks in advance!

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• Adding Timestamp to Java's GC messages in Tomcat 6

  - by ripper234

  I turned on Java's GC log options -XX:+PrintGC -XX:+PrintGCTimeStamps -XX:+PrintGCDetails Which print out these messages to standard output (catalina.out): 314.884: [CMS-concurrent-mark-start] 315.014: [CMS-concurrent-mark: 0.129/0.129 secs] [Times: user=0.14 sys=0.00, real=0.13 secs] 315.014: [CMS-concurrent-preclean-start] 315.016: [CMS-concurrent-preclean: 0.003/0.003 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] 315.016: [CMS-concurrent-abortable-preclean-start] 332.055: [GC 332.055: [ParNew: 17128K->84K(19136K), 0.0017700 secs] 88000K->70956K(522176K) icms_dc=4 , 0.0018660 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] CMS: abort preclean due to time 352.253: [CMS-concurrent-abortable-preclean: 0.023/37.237 secs] [Times: user=0.78 sys=0.02, real=37.23 secs] How can I make these log lines appear with an actual timestamp (including date) instead of these numbers, which presumably mean "time since JVM started" ?

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