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  • Predefining C Array

    - by Johannes Jensen
    In C, when defining an array I can do the following: int arr[] = {5, 2, 9, 8}; And thus I defined it and filled it up, but how do I define it in my .h file, and then fill it in my .c? Like do something like int arr[]; arr = {5, 2, 9, 8}; I'm pretty new to C, not sure how it would look any suggestions?

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  • Why wont numpy matrix let me print its rows?

    - by uberjumper
    Okay this is probably a really dumb question, however its really starting to hurt. I have a numpy matrix, and basically i print it out row by row. However i want to make each row be formatted and separated properly. >>> arr = numpy.matrix([[x for x in range(5)] for y in range(5)]) >>> arr matrix([[0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4]]) Lets say i want to print the first row, and add a '|' between each element: >>> '|'.join(map(str, arr[0,])) '[[0 1 2 3 4]]' Err... >>> '|'.join(map(lambda x: str(x[0]), arr[0])) '[[0 1 2 3 4]]' I am really confused by this behavior why does it do this?

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  • Reading a triangle of numbers into a 2d array of ints in Python

    - by Gabriel Silk
    I want to read a triangle of integer values from a file into a 2D array of ints using Python. The numbers would look like this: 75 95 64 17 47 82 18 35 87 10 20 04 82 47 65 ... The code I have so far is as follows: f = open('problem18.input', 'r') arr = [] for i in range(0, 15): arr.append([]) str = f.readline() a = str.split(' ') for tok in a: arr[i].append(int(tok[:2])) print arr I have a feeling this could be done in a tighter, more Pythonesque way. How would you do it?

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  • WriteableBitmap failing badly, pixel array very inaccurate

    - by dawmail333
    I have tried, literally for hours, and I have not been able to budge this problem. I have a UserControl, that is 800x369, and it contains, simply, a path that forms a worldmap. I put this on a landscape page, then I render it into a WriteableBitmap. I then run a conversion to turn the 1d Pixels array into a 2d array of integers. Then, to check the conversion, I wire up the custom control's click command to use the Point.X and Point.Y relative to the custom control in the newly created array. My logic is thus: wb = new WriteableBitmap(worldMap, new TranslateTransform()); wb.Invalidate(); intTest = wb.Pixels.To2DArray(wb.PixelWidth); My conversion logic is as such: public static int[,] To2DArray(this int[] arr,int rowLength) { int[,] output = new int[rowLength, arr.Length / rowLength]; if (arr.Length % rowLength != 0) throw new IndexOutOfRangeException(); for (int i = 0; i < arr.Length; i++) { output[i % rowLength, i / rowLength] = arr[i]; } return output; } Now, when I do the checking, I get completely and utterly strange results: apparently all pixels are either at values of -1 or 0, and these values are completely independent of the original colours. Just for posterity: here's my checking code: private void Check(object sender, MouseButtonEventArgs e) { Point click = e.GetPosition(worldMap); ChangeNotification(intTest[(int)click.X,(int)click.Y].ToString()); } The result show absolutely no correlation to the path that the WriteableBitmap has rendered into it. The path has a fill of solid white. What the heck is going on? I've tried for hours with no luck. Please, this is the major problem stopping me from submitting my first WP7 app. Any guidance?

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  • [PHP] using the magic __set() method with 2D arrays

    - by Spoonface
    If I have the following registry class: Class registry { private $_vars; public function __construct() { $this->_vars = array(); } public function __set($key, $val) { $this->_vars[$key] = $val; } public function __get($key) { if (isset($this->_vars[$key])) return $this->_vars[$key]; } public function printAll() { print "<pre>".print_r($this->_vars,true)."</pre>"; } } $reg = new registry(); $reg->arr = array(1,2,3); $reg->arr = array_merge($reg->arr,array(4)); $reg->printAll(); Would there be an easier way to push a new item onto the 'arr' array? This code: 'array[] = item' doesn't work with the magic set method, and I couldn't find any useful info with google. Thanks for your time!

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  • optimize 2D array in C++

    - by Hristo
    I'm dealing with a 2D array with the following characteristics: const int cols = 500; const int rows = 100; int arr[rows][cols]; I access array arr in the following manner to do some work: for(int k = 0; k < T; ++k) { // for each trainee myscore[k] = 0; for(int i = 0; i < N; ++i) { // for each sample for(int j = 0; j < E[i]; ++j) { // for each expert myscore[k] += delta(i, anotherArray[k][i], arr[j][i]); } } } So I am worried about the array 'arr' and not the other one. I need to make this more cache-friendly and also boost the speed. I was thinking perhaps transposing the array but I wasn't sure how to do that. My implementation turns out to only work for square matrices. How would I make it work for non-square matrices? Also, would mapping the 2D array into a 1D array boost the performance? If so, how would I do that? Finally, any other advice on how else I can optimize this... I've run out of ideas, but I know that arr[j][i] is the place where I need to make changes because I'm accessing columns by columns instead of rows by rows so that is not cache friendly at all. Thanks, Hristo

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  • Thread-safty of boost RNG

    - by Maciej Piechotka
    I have a loop which should be nicely pararellized by insering one openmp pragma: boost::normal_distribution<double> ddist(0, pow(retention, i - 1)); boost::variate_generator<gen &, BOOST_TYPEOF(ddist)> dgen(rng, ddist); // Diamond const std::uint_fast32_t dno = 1 << i - 1; // #pragma omp parallel for for (std::uint_fast32_t x = 0; x < dno; x++) for (std::uint_fast32_t y = 0; y < dno; y++) { const std::uint_fast32_t diff = size/dno; const std::uint_fast32_t x1 = x*diff, x2 = (x + 1)*diff; const std::uint_fast32_t y1 = y*diff, y2 = (y + 1)*diff; double avg = (arr[x1][y1] + arr[x1][y2] + arr[x2][y1] + arr[x2][y2])/4; arr[(x1 + x2)/2][(y1 + y2)/2] = avg + dgen(); } (unless I make an error each execution does not depend on others at all. Sorry that not all of code is inserted). However my question is - are boost RNG thread-safe? They seems to refer to gcc code for gcc so even if gcc code is thread-safe it may not be the case for other platforms.

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  • Sorting an array of objects in ActionScript 3

    - by vitto
    Hi, I'm trying to sort an array of objects with ActionScript 3. The array is like this: var arr:Array = new Array (); arr.push ({name:"John", date:"20080324", message:"Hi"}); arr.push ({name:"Susan", date:"20090528", message:"hello"}); can I do something with Array.sort(...) method?

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  • Array not returned correct

    - by hp1
    Hello, I am trying to return a simple array, but I am not getting the correct result. I am getting the following arr1[0] = 1 arr1[1] = 32767 result while the result should have been arr1[0] = 1 arr1[1] = 15 Please suggest. int *sum(int a, int b){ int arr[2]; int *a1; int result = a+b; arr[0]= 1; arr[1]= result; a1 = arr; return a1; } int main(){ int *arr1 = sum(5,10); cout<<"arr1[0] = "<<arr1[0]<<endl; cout<<"arr1[1] = "<<arr1[1]<<endl; return 0; }

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  • For-Each and Pointers in Java

    - by John
    Ok, so I'm tyring to iterate through an ArrayList and remove a specefic element. However, I am having some trouble using the For-Each like structure. When I run the following code: ArrayList<String> arr = new ArrayList<String>(); //... fill with some values (doesn't really matter) for(String t : arr) { t = " some other value "; //hoping this would change the actual array } for(String t : arr) { System.out.println(t); //however, I still get the same array here } My question in, how can I make 't' a pointer to 'arr' so that I am able to change the values in a for-each loop? I know I could loop through the ArrayList using a different structure, but this one looks so clean and readable, it would just be nice to be able to make 't' a pointer. All comments are appreciated! Even if you say I should just suck it up and use a different construct.

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  • collection_check_boxes get value

    - by 24sharon
    this is my view code <%=collection_check_boxes(nil, :admin_ids, Admin.all, :id, :name )%> but when i try get the value in the controller i get always an empty value if the user doesnt check any item and the length is always more than zero when i write this code arr = params[:admin_ids] ||= [] puts arr.length ther arr.length is 1 even if the user doesnt select any of the items how can i get an array of selected items only with no empty values

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  • retrive file line one by one using C#?

    - by riad
    Dear all, I have a file name abc.txt.On that file have some lines like this: jani 50,south carolina,USA karim 16,roam,Italy fara 52,sydny,Australia first line is name and second line is address.Now i need the info name on a string let say nameString and address is let say addressString.How can i do it using C#? I write a code in PHP its working smoothly.I need the same thing in C#.For yours clarification here is the php code: $file=file_get_contents('abc.txt'); $arr=explode("\n",$file); for ($i=0;$i<count($arr);$i=$i+2) { $name=$arr[$i]; $address=$arr[$i+1]; echo $name ."<br/>"; echo $address. "<br/>"; } How can i do the same thing in C#???? Another question: IS their any function in C# as like as explode in php? thanks in advance riad

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  • MACRO compilation PROBLEM

    - by wildfly
    i was given a primitive task to find out (and to put in cl) how many nums in an array are bigger than the following ones, (meaning if (arr[i] arr[i+1]) count++;) but i've problems as it has to be a macro. i am getting errors from TASM. can someone give me a pointer? SortA macro a, l LOCAL noes irp reg, <si,di,bx> push reg endm xor bx,bx xor si,si rept l-1 ;;also tried rept 3 : wont' compile mov bl,a[si] inc si cmp bl,arr[si] jb noes inc di noes: add di,0 endm mov cx,di irp reg2, <bx,di,si> pop reg2 endm endm dseg segment arr db 10,9,8,7 len = 4 dseg ends sseg segment stack dw 100 dup (?) sseg ends cseg segment assume ds:dseg, ss:sseg, cs:cseg start: mov ax, dseg mov ds,ax sortA arr,len cseg ends end start errors: Assembling file: sorta.asm **Error** sorta.asm(51) REPT(4) Expecting pointer type **Error** sorta.asm(51) REPT(6) Symbol already different kind: NOES **Error** sorta.asm(51) REPT(10) Expecting pointer type **Error** sorta.asm(51) REPT(12) Symbol already different kind: NOES **Error** sorta.asm(51) REPT(16) Expecting pointer type **Error** sorta.asm(51) REPT(18) Symbol already different kind: NOES Error messages: 6

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  • How do I get a slice from an array reference?

    - by Sachin
    Let us say that we have following array: my @arr=('Jan','Feb','Mar','Apr'); my @arr2=@arr[0..2]; How can we do the same thing if we have array reference like below: my $arr_ref=['Jan','Feb','Mar','Apr']; my $arr_ref2; # How can we do something similar to @arr[0..2]; using $arr_ref ?

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  • creating an array of objects in c++

    - by tim22
    I'm trying to create an array of objects in c++. I'm creating a employee object, from my constructor in my company class here: employee obj(int tempIdNum, double tempBase, double tempSales, double tempRate); emp[tempcount]=obj; (this doesn't work?) Emp is the name of the array which is defined here, located in my company h file. Employee emp[4]; more code: Company::Company(string name, string fileName){ string str; int tempcount; int tempIdnum; double tempBase; double tempSales; double tempRate; double num; double arr[16]; this->name=name; //Commission temp; ifstream readFile; readFile.open("fileName"); int inc=0; while(tempcount<4){ for(int i=0+inc; i<4+inc; i++){ readFile>>num; arr[i-inc]=num; } tempIdnum=(int)(arr[0]); tempBase=arr[1]; tempSales=arr[2]; tempRate=arr[3]; Employee obj(int tempIdNum, double tempBase, double tempSales, double tempRate); emp[tempcount]=obj; inc+=4; tempcount++; } readFile.close(); } Here is some more from my h file #include <string> include "Commission.h" using namespace std; ifndef Company_H define Company_H class Company{ private: string name; //name of company Employee emp[4]; //array of payrool info about 4 commission employees int numEmp; //number of employees public: Company(); Company(string name, string fileName); ~Company(); string getName(); Commission getEmployee(int element); int getNumEmp(); }; endif enter code here Does not compile: 46 E:\exercise2\Company.cpp no match for 'operator=' in '((Company*)this)-Company::emp[tempcount] = obj'

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  • Can I use "map" as a substitute for "for each"/"for in"?

    - by John Mee
    For a little while now javascript has the "map" function to loop over arrays. It appears possible to use it as a 'foreach' operator for example: var arr = ['a','b','c'] var doubles = arr.map(function(val){ return val + val }) Is this better or worse than saying for(var i in arr){ ... 50/50: saves having to use the index but adds a callback; it doesn't seem very common so I hesitate to use it but still want to.

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  • Apply function to one element of a list in Python

    - by user189637
    I'm looking for a concise and functional style way to apply a function to one element of a tuple and return the new tuple, in Python. For example, for the following input: inp = ("hello", "my", "friend") I would like to be able to get the following output: out = ("hello", "MY", "friend") I came up with two solutions which I'm not satisfied with. One uses a higher-order function. def apply_at(arr, func, i): return arr[0:i] + [func(arr[i])] + arr[i+1:] apply_at(inp, lambda x: x.upper(), 1) One uses list comprehensions (this one assumes the length of the tuple is known). [(a,b.upper(),c) for a,b,c in [inp]][0] Is there a better way? Thanks!

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  • sum of square of each elements in the vector using for_each

    - by pierr
    Hi, As the function accepted by for_each take only one parameter (the element of the vector), I have to define a static int sum = 0 somewhere so that It can be accessed after calling the for_each . I think this is awkward. Any better way to do this (still use for_each) ? #include <algorithm> #include <vector> #include <iostream> using namespace std; static int sum = 0; void add_f(int i ) { sum += i * i; } void test_using_for_each() { int arr[] = {1,2,3,4}; vector<int> a (arr ,arr + sizeof(arr)/sizeof(arr[0])); for_each( a.begin(),a.end(), add_f); cout << "sum of the square of the element is " << sum << endl; } In Ruby, We can do it this way: sum = 0 [1,2,3,4].each { |i| sum += i*i} #local variable can be used in the callback function puts sum #=> 30 Would you please show more examples how for_each is typically used in practical programming (not just print out each element)? Is it possible use for_each simulate 'programming pattern' like map and inject in Ruby (or map /fold in Haskell). #map in ruby >> [1,2,3,4].map {|i| i*i} => [1, 4, 9, 16] #inject in ruby [1, 4, 9, 16].inject(0) {|aac ,i| aac +=i} #=> 30 EDIT: Thank you all. I have learned so much from your replies. We have so many ways to do the same single thing in C++ , which makes it a little bit difficult to learn. But it's interesting :)

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  • Optimizing simple search script in PowerShell

    - by cc0
    I need to create a script to search through just below a million files of text, code, etc. to find matches and then output all hits on a particular string pattern to a CSV file. So far I made this; $location = 'C:\Work*' $arr = "foo", "bar" #Where "foo" and "bar" are string patterns I want to search for (separately) for($i=0;$i -lt $arr.length; $i++) { Get-ChildItem $location -recurse | select-string -pattern $($arr[$i]) | select-object Path | Export-Csv "C:\Work\Results\$($arr[$i]).txt" } This returns to me a CSV file named "foo.txt" with a list of all files with the word "foo" in it, and a file named "bar.txt" with a list of all files containing the word "bar". Is there any way anyone can think of to optimize this script to make it work faster? Or ideas on how to make an entirely different, but equivalent script that just works faster? All input appreciated!

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  • Delphi SetLength Custom Indexing

    - by Andreas Rejbrand
    In Delphi, it is possible to create an array of the type var Arr: array[2..N] of MyType; which is an array of N - 1 elements indexed from 2 to N. If we instead declare a dynamic array var Arr: array of MyType and later allocate N - 1 elements by means of SetLength(Arr, N - 1) then the elements will be indexed from 0 to N - 2. Is it possible to make them indexed from 2 to N (say) instead?

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  • How much memory is reserved when i declare a string?

    - by Bhagya
    What exactly happens, in terms of memory, when i declare something like: char arr[4]; How many bytes are reserved for arr? How is null string accommodated when I 'strcpy' a string of length 4 in arr? I was writing a socket program, and when I tried to suffix NULL at arr[4] (i.e. the 5th memory location), I ended up replacing the values of some other variables of the program (overflow) and got into a big time mess. Any descriptions of how compilers (gcc is what I used) manage memory?

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  • Android / Java rare and seemingly impossible exception causing force close

    - by Guzba
    Hello all, I have an interesting problem being reported to me from an android application I have published. I have a two-dimensional array that I am iterating through using two for loops like so: for (int i = 0; i < arr.length; ++i) { for (int j = 0; j < arr[i].length; ++j) { if (arr[i][j] != 0) // does stuff } } The problem is, somehow arr[i][j] != 0 is throwing an ArrayIndexOutOfBoundsException. But very rarely. I have thousands of people use the app on a daily basis and get maybe twenty force close reports. Is this something I can't avoid, maybe a problem with the phones memory, etc. or is there something I can do that I haven't thought of yet? Thanks.

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  • How to implement iterator as an attribute of a class in Java

    - by de3
    Hi, let's say I have this simple MyArray class, with two simple methods: add, delete and an iterator. In the main method we can see how it is supposed to be used: public class MyArray { int start; int end; int[] arr; myIterator it; public MyArray(){ this.start=0; this.end=0; this.arr=new int[500]; it=new myIterator(); } public void add(int el){ this.arr[this.end]=el; this.end++; } public void delete(){ this.arr[this.start]=0; this.start++; } public static void main(String[] args){ MyArray m=new MyArray(); m.add(3); m.add(299); m.add(19); m.add(27); while(m.it.hasNext()){ System.out.println(m.it.next()); } } And then MyIterator should be implemented somehow: import java.util.Iterator; public class myIterator implements Iterator{ @Override public boolean hasNext() { // TODO Auto-generated method stub return false; } @Override public Object next() { // TODO Auto-generated method stub return null; } @Override public void remove() { // TODO Auto-generated method stub } } MyIterator should iterate arr from MyArray class, from start to end values; both are also attributes of MyArray. So, as MyIterator should use MyArray attributes, how should MyIterator be implemented? Perhaps I can send the current object in the initialization: it=new myIterator(this); But I guess it's not the best soultion. Or maybe MyArray itself should implement Iterator interface? How is this solved?

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  • Textarea into an array or implode?

    - by Kyle R
    Say I have a text area, user enters information exactly like styled below: Ice cream Chocolate then submits this information, I want to retrieve the information EXACTLY like so: Ice cream, Chocolate Is this the best way to do it: $arr = explode("\n", $var); $arr = implode(",", $arr); When doing it like this, it puts the information out like so: Ice cream , Chocolate Note the space after cream, will a simple trim() fix this?

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