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  • Why do Core Data sqlite table columns start with 'Z'?

    - by Dia
    I was looking at the sqlite table that Core Data generates and noticed that all table columns start with 'Z'. I realize this is an implementation detail, but I was curious as to why that's the case and if there was a design decision involved in this. Anyone happen to know or guess why? Here's a sample schema output of Core Data sqlite database: sqlite .schema CREATE TABLE ZPOST ( Z_PK INTEGER PRIMARY KEY, Z_ENT INTEGER, Z_OPT INTEGER, ZPOSTID INTEGER, ZUSER INTEGER, ZCREATEDAT TIMESTAMP, ZTEXT VARCHAR ); CREATE TABLE ZUSER ( Z_PK INTEGER PRIMARY KEY, Z_ENT INTEGER, Z_OPT INTEGER, ZUSERID INTEGER, ZAVATARIMAGEURLSTRING VARCHAR, ZUSERNAME VARCHAR ); CREATE TABLE Z_METADATA (Z_VERSION INTEGER PRIMARY KEY, Z_UUID VARCHAR(255), Z_PLIST BLOB); CREATE TABLE Z_PRIMARYKEY (Z_ENT INTEGER PRIMARY KEY, Z_NAME VARCHAR, Z_SUPER INTEGER, Z_MAX INTEGER);

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  • C: 8x8 -> 16 bit multiply precision guaranteed by integer promotions?

    - by craig-blome
    I'm trying to figure out if the C Standard (C90, though I'm working off Derek Jones' annotated C99 book) guarantees that I will not lose precision multiplying two unsigned 8-bit values and storing to a 16-bit result. An example statement is as follows: unsigned char foo; unsigned int foo_u16 = foo * 10; Our Keil 8051 compiler (v7.50 at present) will generate a MUL AB instruction which stores the MSB in the B register and the LSB in the accumulator. If I cast foo to a unsigned int first: unsigned int foo_u16 = (unsigned int)foo * 10; then the compiler correctly decides I want a unsigned int there and generates an expensive call to a 16x16 bit integer multiply routine. I would like to argue beyond reasonable doubt that this defensive measure is not necessary. As I read the integer promotions described in 6.3.1.1, the effect of the first line shall be as if foo and 10 were promoted to unsigned int, the multiplication performed, and the result stored as unsigned int in foo_u16. If the compiler knows an instruction that does 8x8-16 bit multiplications without loss of precision, so much the better; but the precision is guaranteed. Am I reading this correctly? Best regards, Craig Blome

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  • Using "from __future__ import division" in my program, but it isn't loaded with my program

    - by Sara Fauzia
    I wrote the following program in Python 2 to do Newton's method computations for my math problem set, and while it works perfectly, for reasons unbeknownst to me, when I initially load it in ipython with %run -i NewtonsMethodMultivariate.py, the Python 3 division is not imported. I know this because after I load my Python program, entering x**(3/4) gives "1". After manually importing the new division, then x**(3/4) remains x**(3/4), as expected. Why is this? # coding: utf-8 from __future__ import division from sympy import symbols, Matrix, zeros x, y = symbols('x y') X = Matrix([[x],[y]]) tol = 1e-3 def roots(h,a): def F(s): return h.subs({x: s[0,0], y: s[1,0]}) def D(s): return h.jacobian(X).subs({x: s[0,0], y: s[1,0]}) if F(a) == zeros(2)[:,0]: return a else: while (F(a)).norm() > tol: a = a - ((D(a))**(-1))*F(a) print a.evalf(10) I would use Python 3 to avoid this issue, but my Linux distribution only ships SymPy for Python 2. Thanks to the help anyone can provide. Also, in case anyone was wondering, I haven't yet generalized this script for nxn Jacobians, and only had to deal with 2x2 in my problem set. Additionally, I'm slicing the 2x2 zero matrix instead of using the command zeros(2,1) because SymPy 0.7.1, installed on my machine, complains that "zeros() takes exactly one argument", though the wiki suggests otherwise. Maybe this command is only for the git version.

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  • CVE-2010-1634 Integer Overflow vulnerability in Python

    - by chandan
    CVE DescriptionCVSSv2 Base ScoreComponentProduct and Resolution CVE-2010-1634 Integer Overflow vulnerability 5.0 Python Solaris 10 SPARC: 143506-03 X86: 143507-03 Solaris 11 Contact Support This notification describes vulnerabilities fixed in third-party components that are included in Sun's product distribution.Information about vulnerabilities affecting Oracle Sun products can be found on Oracle Critical Patch Updates and Security Alerts page.

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  • How to deal with 2 almost identical tables

    - by jgritty
    I have a table of baseball stats, something like this: CREATE TABLE batting_stats( ab INTEGER, pa INTEGER, r INTEGER, h INTEGER, hr INTEGER, rbi INTEGER, playerID INTEGER, FOREIGN KEY(playerID) REFERENCES player(playerID) ); But then I have a table of stats that are basically exactly the same, but for a team: CREATE TABLE team_batting_stats( ab INTEGER, pa INTEGER, r INTEGER, h INTEGER, hr INTEGER, rbi INTEGER, teamID INTEGER, FOREIGN KEY(teamID) REFERENCES team(teamID) ); My first instinct is to scrap the Foreign key and generalize the ID, but I still have a problem, I have these 2 tables, and they can't have overlapping IDs: CREATE TABLE player( playerID INTEGER PRIMARY KEY, firstname TEXT, lastname TEXT, number INTEGER, teamID INTEGER, FOREIGN KEY(teamID) REFERENCES team(teamID) ); CREATE TABLE team( teamID INTEGER PRIMARY KEY, name TEXT, city TEXT, ); I feel like I'm overlooking something obvious that could solve this problem and reduce stats to a single table.

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  • How to store a reference to an integer in C#?

    - by Jonathon Reinhart
    Hello everyone - tell me how to make this work? Basically, I need an integer reference type (int* would work in C++) class Bar { private ref int m_ref; // This doesn't exist public A(ref int val) { m_ref = val; } public void AddOne() { m_ref++; } } class Program { static void main() { int foo = 7; Bar b = new Bar(ref foo); b.AddOne(); Console.WriteLine(foo); // This should print '8' } } Do I have to use boxing?

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  • php encrypting an integer to get only alphanumeric characters?

    - by Matthew Steiner
    When I use some of php's encryption functions, I end up getting a few characters I don't want (+, /, =). The problem is that my application doesn't allow these in the url. I'm wondering if there's a good way of encrypting an integer and having only alphanumeric characters in the result? I'm trying to pass some data through the url. I know it's possible to do some workarounds (put data in database and pass the id to the row or something), but I really want to try it this way. Ideas?

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  • How to find multiples of the same integer in an arraylist?

    - by Dan
    Hi My problem is as follows. I have an arraylist of integers. The arraylist contains 5 ints e.g[5,5,3,3,9] or perhaps [2,2,2,2,7]. Many of the arraylists have duplicate values and i'm unsure how to count how many of each of the values exist. The problem is how to find the duplicate values in the arraylist and count how many of that particular duplicate there are. In the first example [5,5,3,3,9] there are 2 5's and 2 3's. The second example of [2,2,2,2,7] would be only 4 2's. The resulting information i wish to find is if there are any duplicates how many of them there are and what specific integer has been duplicated. I'm not too sure how to do this in java. Any help would be much appreciated. Thanks.

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  • Is it possible to cast the Elapsed Time function to Integer?

    - by nuvio
    I have the following function: (def elapsedtime (with-out-str (time (run-my-function)))) and I was wondering if is possible to store only the integer value of the time, as I can only store a String at the moment.... Any suggestion? Thanks a lot UPDATE So I did use this: (defmacro nsecs [expr] `(let [start# (. System (nanoTime))] ~expr (- (. System (nanoTime)) start#))) And then modified this: (def elapsedtime (nsecs (run-my-function argument1 argument2))) but doesn't work, what am I doing wrong? "Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: Wrong number of args (1) passed to: main$fn--105$nsecs"

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  • How to parse a string to an integer without library functions?

    - by dack
    Hi, I was recently asked this question in an interview: "How could you parse a string of the form '12345' into its integer representation 12345 without using any library functions, and regardless of language?" I thought of two answers, but the interviewer said there was a third. Here are my two solutions: Solution 1: Keep a dictionary which maps '1' = 1, '2' = 2, etc. Then parse the string one character at a time, look up the character in your dictionary, and multiply by place value. Sum the results. Solution 2: Parse the string one character at a time and subtract '0' from each character. This will give you '1' - '0' = 0x1, '2' - '0' = 0x2, etc. Again, multiply by place value and sum the results. Can anyone think of what a third solution might be? Thanks.

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  • Java ternary operator and boxing Integer/int?

    - by Markus
    I tripped across a really strange NullPointerException the other day caused by an unexpected type-cast in the ternary operator. Given this (useless exemplary) function: Integer getNumber() { return null; } I was expecting the following two code segments to be exactly identical after compilation: Integer number; if (condition) { number = getNumber(); } else { number = 0; } vs. Integer number = (condition) ? getNumber() : 0; . Turns out, if condition is true, the if-statement works fine, while the ternary opration in the second code segment throws a NullPointerException. It seems as though the ternary operation has decided to type-cast both choices to int before auto-boxing the result back into an Integer!?! In fact, if I explicitly cast the 0 to Integer, the exception goes away. In other words: Integer number = (condition) ? getNumber() : 0; is not the same as: Integer number = (condition) ? getNumber() : (Integer) 0; . So, it seems that there is a byte-code difference between the ternary operator and an equivalent if-else-statement (something I didn't expect). Which raises three questions: Why is there a difference? Is this a bug in the ternary implementation or is there a reason for the type cast? Given there is a difference, is the ternary operation more or less performant than an equivalent if-statement (I know, the difference can't be huge, but still)?

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  • Given an integer, determine if it is a Palindrome in less than O(n) [on hold]

    - by user134235
    There is an O(n) solution to the problem of determining if an integer is a palindrome below. Is it possible to solve this problem in O(log n) or better? static void IsPalindrome(int Number) { int OrignalNum = Number; int Reverse = 0; int Remainder = 0; if (Number > 0) { while (Number > 0) { Remainder = Number % 10; Reverse = Reverse * 10 + Remainder; Number = Number / 10; } if (OrignalNum == Reverse) Console.WriteLine("It is a Palindrome"); else Console.WriteLine("It is not a Palindrome"); } else Console.WriteLine("Enter Number Again"); }

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  • Using a texture as an integer array (OpenGL 3.3, shader version 3.3)

    - by Cubic
    I'm trying to have something like an integer array uniform for my fragment shader (I only need read access). Since it's a fairly large chunk of data (not so large that uploading it in every frame would be impossible, but enough to make me want to rather not do it). Essentially I want to just pass it a uniform telling the shader where this "array" is. I believe I can use a 1D texture for this, but I don't know how (actually, I don't know how to do many things because I just can't seem to find a reference for GLSL 3.3, I only ever find references for the C API). This sounds like a rather basic question and I'm sure it's been answered already somewhere, but I keep searching and can't quite find what I'm looking for.

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  • Searching integer sequences

    - by David Gibson
    I have a fairly complex search problem that I've managed to reduce to the following description. I've been googling but haven't been able to find an algorithm that seems to fit my problem cleanly. In particular the need to skip arbitrary integers. Maybe someone here can point me to something? Take a sequence of integers A, for example (1 2 3 4) Take various sequences of integers and test if any of them match A such that. A contains all of the integers in the tested sequence The ordering of the integers in the tested sequence are the same in A We don't care about any integers in A that are not in the test sequence We want all matching test sequences, not just the first. An example A = (1 2 3 4) B = (1 3) C = (1 3 4) D = (3 1) E = (1 2 5) B matches A C matches A D does not match A as the ordering is different E does not match A as it contains an integer not in A I hope that this explanation is clear enough. The best I've managed to do is to contruct a tree of the test sequences and iterate over A. The need to be able to skip integers leads to a lot of unsuccessful search paths. Thanks Reading some suggestions I feel that I have to clarify a couple of points that I left too vague. Repeated numbers are allowed, in fact this is quite important as it allows a single test sequence to match A is multiple ways A = (1234356), B = (236), matches could be either -23---6 or -2--3-6 I expect there to be a very large number of test sequences, in the thousands at least and sequence A will tend to have a max length of maybe 20. Thus simply trying to match each test sequence one by one by iterating becomes extremely inefficient. Sorry if this wasn't clear.

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  • How to define an Integer bean in Struts 1.x

    - by ian_scho_es
    Hi. How do you instantiate an Integer bean, assigning a value, in the Struts 1.x framework? <bean:define id="index" type="java.lang.Integer" value="0"/> or <bean:define id="index" type="java.lang.Integer" value="${0}"/> Results in a: java.lang.ClassCastException: java.lang.String <bean:define id="index" type="java.lang.Integer" value="<%=0%>"/> Results in: The method setValue(String) in the type DefineTag is not applicable for the arguments (int) <% java.lang.Integer index = new java.lang.Integer(0); %> Works, but makes my eyes bleed. Note that I had to refactor iterating over a list but am now applying a filter within the iteration. This was the cleanest solution of all! <logic:equal name="aplicacion" property="generico" value="false" indexId="index"> Maybe I need to go about this completely differently. Many thanks.

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  • How to obtain a random sub-datatable from another data table

    - by developerit
    Introduction In this article, I’ll show how to get a random subset of data from a DataTable. This is useful when you already have queries that are filtered correctly but returns all the rows. Analysis I came across this situation when I wanted to display a random tag cloud. I already had the query to get the keywords ordered by number of clicks and I wanted to created a tag cloud. Tags that are the most popular should have more chance to get picked and should be displayed larger than less popular ones. Implementation In this code snippet, there is everything you need. ' Min size, in pixel for the tag Private Const MIN_FONT_SIZE As Integer = 9 ' Max size, in pixel for the tag Private Const MAX_FONT_SIZE As Integer = 14 ' Basic function that retreives Tags from a DataBase Public Shared Function GetTags() As MediasTagsDataTable ' Simple call to the TableAdapter, to get the Tags ordered by number of clicks Dim dt As MediasTagsDataTable = taMediasTags.GetDataValide ' If the query returned no result, return an empty DataTable If dt Is Nothing OrElse dt.Rows.Count < 1 Then Return New MediasTagsDataTable End If ' Set the font-size of the group of data ' We are dividing our results into sub set, according to their number of clicks ' Example: 10 results -> [0,2] will get font size 9, [3,5] will get font size 10, [6,8] wil get 11, ... ' This is the number of elements in one group Dim groupLenth As Integer = CType(Math.Floor(dt.Rows.Count / (MAX_FONT_SIZE - MIN_FONT_SIZE)), Integer) ' Counter of elements in the same group Dim counter As Integer = 0 ' Counter of groups Dim groupCounter As Integer = 0 ' Loop througt the list For Each row As MediasTagsRow In dt ' Set the font-size in a custom column row.c_FontSize = MIN_FONT_SIZE + groupCounter ' Increment the counter counter += 1 ' If the group counter is less than the counter If groupLenth <= counter Then ' Start a new group counter = 0 groupCounter += 1 End If Next ' Return the new DataTable with font-size Return dt End Function ' Function that generate the random sub set Public Shared Function GetRandomSampleTags(ByVal KeyCount As Integer) As MediasTagsDataTable ' Get the data Dim dt As MediasTagsDataTable = GetTags() ' Create a new DataTable that will contains the random set Dim rep As MediasTagsDataTable = New MediasTagsDataTable ' Count the number of row in the new DataTable Dim count As Integer = 0 ' Random number generator Dim rand As New Random() While count < KeyCount Randomize() ' Pick a random row Dim r As Integer = rand.Next(0, dt.Rows.Count - 1) Dim tmpRow As MediasTagsRow = dt(r) ' Import it into the new DataTable rep.ImportRow(tmpRow) ' Remove it from the old one, to be sure not to pick it again dt.Rows.RemoveAt(r) ' Increment the counter count += 1 End While ' Return the new sub set Return rep End Function Pro’s This method is good because it doesn’t require much work to get it work fast. It is a good concept when you are working with small tables, let says less than 100 records. Con’s If you have more than 100 records, out of memory exception may occur since we are coping and duplicating rows. I would consider using a stored procedure instead.

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