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  • How to define and use a friend function to a temlate class with the same template?

    - by Narek
    I have written the following code: #include <iostream> using namespace std; template <class T> class AA { T a; public: AA() { a = 7; } friend void print(const AA<T> & z); }; template <class T> void print(const AA<T> & z) { cout<<"Print: "<<z.a<<endl; } void main() { AA<int> a; print<int>(a); } And getting the following error: error C2248: 'AA<T>::a' : cannot access private member declared in class 'AA<T>' 1> with 1> [ 1> T=int 1> ] 1> c:\users\narek\documents\visual studio 2008\projects\aaa\aaa\a.cpp(7) : see declaration of 'AA<T>::a' 1> with 1> [ 1> T=int 1> ] 1> c:\users\narek\documents\visual studio 2008\projects\aaa\aaa\a.cpp(30) : see reference to function template instantiation 'void print<int>(const AA<T> &)' being compiled 1> with 1> [ 1> T=int 1> ] What's wrong?

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  • Recursive templates: compilation error under g++

    - by Johannes
    Hi, I am trying to use templates recursively to define (at compile-time) a d-tuple of doubles. The code below compiles fine with Visual Studio 2010, but g++ fails and complains that it "cannot call constructor 'point<1::point' directly". Could anyone please shed some light on what is going on here? Many thanks, Jo #include <iostream> #include <utility> using namespace std; template <const int N> class point { private: pair<double, point<N-1> > coordPointPair; public: point() { coordPointPair.first = 0; coordPointPair.second.point<N-1>::point(); } }; template<> class point<1> { private: double coord; public: point() { coord= 0; } }; int main() { point<5> myPoint; return 0; }

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  • Function pointers to member functions

    - by Jacob
    There are several duplicates of this but nobody explains why I can use a member variable to store the pointer (in FOO) but when I try it with a local variable (in the commented portion of BAR), it's illegal. Could anybody explain this? #include <iostream> using namespace std; class FOO { public: int (FOO::*fptr)(int a, int b); int add_stuff(int a, int b) { return a+b; } void call_adder(int a, int b) { fptr = &FOO::add_stuff; cout<<(this->*fptr)(a,b)<<endl; } }; class BAR { public: int add_stuff(int a, int b) { return a+b; } void call_adder(int a, int b) { //int (BAR::*fptr)(int a, int b); //fptr = &BAR::add_stuff; //cout<<(*fptr)(a,b)<<endl; } }; int main() { FOO test; test.call_adder(10,20); return 0; }

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  • C++ polymorphism and slicing

    - by Draco Ater
    The following code, prints out Derived Base Base But I need every Derived object put into User::items, call its own print function, but not the base class one. Can I achieve that without using pointers? If it is not possible, how should I write the function that deletes User::items one by one and frees memory, so that there should not be any memory leaks? #include <iostream> #include <vector> #include <algorithm> using namespace std; class Base{ public: virtual void print(){ cout << "Base" << endl;} }; class Derived: public Base{ public: void print(){ cout << "Derived" << endl;} }; class User{ public: vector<Base> items; void add_item( Base& item ){ item.print(); items.push_back( item ); items.back().print(); } }; void fill_items( User& u ){ Derived d; u.add_item( d ); } int main(){ User u; fill_items( u ); u.items[0].print(); }

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  • Copying to binary file row of a matrix

    - by Flethuseo
    Hi everyone I want to write each row of a matrix to a binary file. I try writing it like this: vector< vector<uint32_t> > matrix; ... for(size_t i = 0; i < matrix.size(); ++i) ofile->write( reinterpret_cast<char*>(&matrix[i]), sizeof(uint32_t*sizeof(matrix[i])) ); { for(size_t j = 0; j < numcols; ++j) { std::cout << left << setw(10) << matrix[i][j]; } cout << endl; } but it doesn't work, I get garbage numbers. Any help appreciated, Ted.

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  • Why do I get this strange output behavior?

    - by WilliamKF
    I have the following program test.cc: #include <iostream> unsigned char bogus1[] = { // Changing # of periods (0x2e) changes output after periods. 0x2e, 0x2e, 0x2e, 0x2e }; unsigned int bogus2 = 1816; // Changing this value changes output. int main() { std::clog << bogus1; } I build it with: g++ -g -c -o test.o test.cc; g++ -static-libgcc -o test test.o Using g++ version 3.4.6 I run it through valgrind and nothing is reported wrong. However the output has two extra control characters and looks like this: .... Thats a control-X and a control-G at the end. If you change the value of bogus2 you get different control characters. If you change the number of periods in the array the issue goes away or changes. I suspect it is a memory corruption bug in the compiler or iostream package. What is going on here?

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  • How do i return a template class from a template function?

    - by LoudNPossiblyRight
    It looks logical but for some reason when i uncomment the last cout line, this code does not compile. How do i return a template class? What do i have to do to this code to make it work? #include<iostream> using namespace std; template <int x> class someclass{ public: int size; int intarr[x]; someclass():size(x){} }; template<int x, int y> int somefunc(someclass<x> A, someclass<y> B){ return ( A.size > B.size ? A.size : B.size); } template<int x, int y, int z> someclass<x> anotherfunc(someclass<y> A, someclass<z> B){ return ( A.size > B.size ? A : B); } int main(){ someclass<5> A; someclass<10> B; cout << "SIZE = " << somefunc(A,B) << endl; //cout << "SIZE = " << (anotherfunc(A,B)).size << endl; //THIS DOES NOT COMPILE return 0; }

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  • What is the nicest way to parse this in C++ ?

    - by ereOn
    Hi, In my program, I have a list of "server address" in the following format: host[:port] The brackets here, indicate that the port is optional. host can be a hostname, an IPv4 or IPv6 address. port, if present can be a numeric port number or a service string (like: "http" or "ssh"). If port is present and host is an IPv6 address, host must be in "bracket-enclosed" notation (Example: [::1]) Here are some valid examples: localhost localhost:11211 127.0.0.1:http [::1]:11211 ::1 [::1] And an invalid example: ::1:80 // Invalid: Is this the IPv6 address ::1:80 and a default port, or the IPv6 address ::1 and the port 80 ? ::1:http // This is not ambigous, but for simplicity sake, let's consider this is forbidden as well. My goal is to separate such entries in two parts (obviously host and port). I don't care if either the host or port are invalid as long as they don't contain a : (290.234.34.34.5 is ok for host, it will be rejected in the next process); I just want to separate the two parts, or if there is no port part, to know it somehow. I tried to do something with std::stringstream but everything I come up to seems hacky and not really elegant. How would you do this in C++ ? I don't mind answers in C but C++ is prefered. Any boost solution is welcome as well. Thank you.

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  • Are C++ exceptions sufficient to implement thread-local storage?

    - by Potatoswatter
    I was commenting on an answer that thread-local storage is nice and recalled another informative discussion about exceptions where I supposed The only special thing about the execution environment within the throw block is that the exception object is referenced by rethrow. Putting two and two together, wouldn't executing an entire thread inside a function-catch-block of its main function imbue it with thread-local storage? It seems to work fine: #include <iostream> #include <pthread.h> using namespace std; struct thlocal { string name; thlocal( string const &n ) : name(n) {} }; thlocal &get_thread() { try { throw; } catch( thlocal &local ) { return local; } } void print_thread() { cerr << get_thread().name << endl; } void *kid( void *local_v ) try { thlocal &local = * static_cast< thlocal * >( local_v ); throw local; } catch( thlocal & ) { print_thread(); return NULL; } int main() try { thlocal local( "main" ); throw local; } catch( thlocal & ) { print_thread(); pthread_t th; thlocal kid_local( "kid" ); pthread_create( &th, NULL, &kid, &kid_local ); pthread_join( th, NULL ); print_thread(); return 0; } Is this novel or well-characterized? Was my initial premise correct? What kind of overhead does get_thread incur in, say, GCC and VC++? It would require throwing only exceptions derived from struct thlocal, but altogether this doesn't feel like an unproductive insomnia-ridden Sunday morning…

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  • Callback function and function pointer trouble in C++ for a BST

    - by Brendon C.
    I have to create a binary search tree which is templated and can deal with any data types, including abstract data types like objects. Since it is unknown what types of data an object might have and which data is going to be compared, the client side must create a comparison function and also a print function (because also not sure which data has to be printed). I have edited some C code which I was directed to and tried to template, but I cannot figure out how to configure the client display function. I suspect variable 'tree_node' of class BinarySearchTree has to be passed in, but I am not sure how to do this. For this program I'm creating an integer binary search tree and reading data from a file. Any help on the code or the problem would be greatly appreciated :) Main.cpp #include "BinarySearchTreeTemplated.h" #include <iostream> #include <fstream> #include <string> using namespace std; /*Comparison function*/ int cmp_fn(void *data1, void *data2) { if (*((int*)data1) > *((int*)data2)) return 1; else if (*((int*)data1) < *((int*)data2)) return -1; else return 0; } static void displayNode() //<--------NEED HELP HERE { if (node) cout << " " << *((int)node->data) } int main() { ifstream infile("rinput.txt"); BinarySearchTree<int> tree; while (true) { int tmp1; infile >> tmp1; if (infile.eof()) break; tree.insertRoot(tmp1); } return 0; } BinarySearchTree.h (a bit too big to format here) http://pastebin.com/4kSVrPhm

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  • What's the problem with the code below ?

    - by VaioIsBorn
    #include <iostream> #include <vector> using namespace std; int main(void) { int i, s, g; vector<int> a; cin >> s; for(i=1;i<=s;i++) { g = s; if(g<10) a.push_back(g); else { vector<int> temp; while(g > 0) { int k = g % 10; g = g / 10; temp.push_back(g); } for(int j=temp.size();j>0;j--) { a.push_back(temp[j]); } } } cout << a[s-1] << endl; return 0; } What is wrong with the code above ? It doesn't give me the appropriate results. The vector a is supposed to hold the values from 1, 2, 3...up to s such that a = 12345..910111213... and print to output a[s]. Ex if s=15 a=123456789101112131415 and a[15] = 2 . If someone could tell me what's the problem

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  • c++ tables of unions and structures

    - by newbDeveloper
    I was told to write a program, that creates a union and structure, then creates two-element arrays of unions and structures and fills their fields. I have created a union and a structure, but how to fill their fields in arrays ? #include <iostream> #include <stdlib.h> #include <stdio.h> using namespace std; union complex; union complex{ int i1; long double ld1; } u; struct Person { char* name; int age; bool sex; void show(){ printf("name %s, age %2.0d, sex %1d\n", name , age, sex); }; } person; int main(void) { Person *o = new Person[2]; complex *un = new complex[2]; un[0]->i1=i; system("pause"); return 0; } I've tried un[0]-i1=i; but it's not the proper way to do this.

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  • Ping broadcast on Win XP SP3

    - by PaulH
    I'm trying to ping the broadcast address 255.255.255.255 on WinXP SP3. If I use the command line, I get host error: C:\>ping 255.255.255.255 Ping request could not find host 255.255.255.255. Please check the name and try again. If I try a C++ program using the iphlpapi, IcmpSendEcho() fails and GetLastError returns 11010 IP_REQ_TIMED_OUT. HANDLE h = ::IcmpCreateFile(); IPAddr broadcast = inet_addr( "255.255.255.255" ); BYTE payload[ 32 ] = { 0 }; IP_OPTION_INFORMATION option = { 255, 0, 0, 0, 0 }; // a buffer with room for 32 replies each containing the full payload std::vector< BYTE > replies( 32 * ( sizeof( ICMP_ECHO_REPLY ) + 32 ) ); DWORD res = ::IcmpSendEcho( h, broadcast, payload, sizeof( payload ), &option, &replies[ 0 ], replies.size(), 1000 ); ::IcmpCloseHandle( h ); I can ping the local broadcast 192.168.0.255 with no problem. What do I need to do to ping the global broadcast? Thanks, PaulH

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  • Enumeration trouble: redeclared as different kind of symbol

    - by Matt
    Hello all. I am writing a program that is supposed to help me learn about enumeration data types in C++. The current trouble is that the compiler doesn't like my enum usage when trying to use the new data type as I would other data types. I am getting the error "redeclared as different kind of symbol" when compiling my trangleShape function. Take a look at the relevant code. Any insight is appreciated! Thanks! (All functions are their own .cpp files.) header file #ifndef HEADER_H_INCLUDED #define HEADER_H_INCLUDED #include <iostream> #include <iomanip> using namespace std; enum triangleType {noTriangle, scalene, isoceles, equilateral}; //prototypes void extern input(float&, float&, float&); triangleType extern triangleShape(float, float, float); /*void extern output (float, float, float);*/ void extern myLabel(const char *, const char *); #endif // HEADER_H_INCLUDED main function //8.1 main // this progam... #include "header.h" int main() { float sideLength1, sideLength2, sideLength3; char response; do //main loop { input (sideLength1, sideLength2, sideLength3); triangleShape (sideLength1, sideLength2, sideLength3); //output (sideLength1, sideLength2, sideLength3); cout << "\nAny more triangles to analyze? (y,n) "; cin >> response; } while (response == 'Y' || response == 'y'); myLabel ("8.1", "2/11/2011"); return 0; } triangleShape shape # include "header.h" triangleType triangleShape(sideLenght1, sideLength2, sideLength3) { triangleType triangle; return triangle; }

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  • Any Alternate way for writing to a file other than ofstream

    - by Aditya
    Hi All, I am performing file operations (writeToFile) which fetches the data from a xml and writes into a output file(a1.txt). I am using MS Visual C++ 2008 and in windows XP. currently i am using this method of writing to output file.. 01.ofstreamhdr OutputFile; 02./* few other stmts / 03.hdrOutputFile.open(fileName, std::ios::out); 04. 05.hdrOutputFile << "#include \"commondata.h\""<< endl ; 06.hdrOutputFile << "#include \"Commonconfig.h\"" << endl ; 07.hdrOutputFile << "#include \"commontable.h\"" << endl << endl ; 08. hdrOutputFile << "#pragma pack(push,1)" << endl ; 09.hdrOutputFile << "typedef struct \n {" << endl ; 10./ simliar hdrOutputFiles statements... */.. I have around 250 lines to write.. Is any better way to perform this task. I want to reduce this hdrOutputFile and use a buffer to do this. Please guide me how to do that action. I mean, buff = "#include \"commontable.h\"" + "typedef struct \n {" + ....... hdrOutputFile << buff. is this way possible? Thanks Ramm

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  • Can piping of screen to file change the result of a C++ code?

    - by Biga
    I am having this very weird behaviour with a C++ code: It gives me different results when running with and without piping the screen to a file (reproducible in cygwin and linux). I mean, if I get the same executable and run it like './run' or run it like './run out.log', I get different results! I use std::cout to output to screen, all lines ending with endl; I use ifstream for the input file; I use ofstream for output, all lines ending with endl. I am using g++ 4. Any idea what is going on? UPDATE: I have hard-coded the input data, so 'ifstream' is not used, and problem persists. UPDATE 2: That's getting interesting. I have output three variables that are computed initially, and that's what I get with and without piping direct to screen: 0 -0.02 0 piped: 0 -0.02 1.04083e-17 So there's a round-off difference with and without piping the output! Now, why piping would interefere with an internal computation of the code?

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  • Simple average calculation

    - by sasquatch90
    I'm trying to write program calculating average of given numbers stored in an array. Amount of numbers should be not more than 100, and user should input them until a !int variable is given : #include <iostream> #include <conio.h> using namespace std; double average(int tab[], int i){ int sum=0; for(int j=0; j<i; ++j){ sum+=tab[j]; } return (double)sum/i; } int main() { int tab[100]; int n=0; int number=0; do { if(n < 100){ cout << "Give " << n+1 << " number : "; cin >> number; tab[n]=number; number=0; ++n; } else{ break; } } while( !isdigit(number) ); cout << average(tab, n) << endl; getch(); return 0; } Why after giving char, it prints me 'Give n number:' for all empty cells of my array ? It should end and use only given numbers.

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  • Calling Base Class Functions with Inherited Type

    - by Kein Mitleid
    I can't describe exactly what I want to say but I want to use base class functions with an inherited type. Like I want to declare "Coord3D operator + (Coord3D);" in one class, but if I use it with Vector3D operands, I want it to return Vector3D type instead of Coord3D. With this line of code below, I add two Vector3D's and get a Coord3D in return, as told to me by the typeid().name() function. How do I reorganize my classes so that I get a Vector3D on return? #include <iostream> #include <typeinfo> using namespace std; class Coord3D { public: float x, y, z; Coord3D (float = 0.0f, float = 0.0f, float = 0.0f); Coord3D operator + (Coord3D &); }; Coord3D::Coord3D (float a, float b, float c) { x = a; y = b; z = c; } Coord3D Coord3D::operator+ (Coord3D &param) { Coord3D temp; temp.x = x + param.x; temp.y = y + param.y; temp.z = z + param.z; return temp; } class Vector3D: public Coord3D { public: Vector3D (float a = 0.0f, float b = 0.0f, float c = 0.0f) : Coord3D (a, b, c) {}; }; int main () { Vector3D a (3, 4, 5); Vector3D b (6, 7, 8); cout << typeid(a + b).name(); return 0; }

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  • Variable length argument list - How to understand we retrieved the last argument?

    - by hkBattousai
    I have a Polynomial class which holds coefficients of a given polynomial. One of its overloaded constructors is supposed to receive these coefficients via variable argument list. template <class T> Polynomial<T>::Polynomial(T FirstCoefficient, ...) { va_list ArgumentPointer; va_start(ArgumentPointer, FirstCoefficient); T NextCoefficient = FirstCoefficient; std::vector<T> Coefficients; while (true) { Coefficients.push_back(NextCoefficient); NextCoefficient = va_arg(ArgumentPointer, T); if (/* did we retrieve all the arguments */) // How do I implement this? { break; } } m_Coefficients = Coefficients; } I know that we usually pass an extra parameter which tells the recipient method the total number of parameters, or we pass a sentimental ending parameter. But in order to keep thing short and clean, I don't prefer passing an extra parameter. Is there any way of doing this without modifying the method signature in the example?

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  • Template trick to optimize out allocations

    - by anon
    I have: struct DoubleVec { std::vector<double> data; }; DoubleVec operator+(const DoubleVec& lhs, const DoubleVec& rhs) { DoubleVec ans(lhs.size()); for(int i = 0; i < lhs.size(); ++i) { ans[i] = lhs[i]] + rhs[i]; // assume lhs.size() == rhs.size() } return ans; } DoubleVec someFunc(DoubleVec a, DoubleVec b, DoubleVec c, DoubleVec d) { DoubleVec ans = a + b + c + d; } Now, in the above, the "a + b + c + d" will cause the creation of 3 temporary DoubleVec's -- is there a way to optimize this away with some type of template magic ... i.e. to optimize it down to something equivalent to: DoubleVec ans(a.size()); for(int i = 0; i < ans.size(); i++) ans[i] = a[i] + b[i] + c[i] + d[i]; You can assume all DoubleVec's have the same # of elements. The high level idea is to have do some type of templateied magic on "+", which "delays the computation" until the =, at which point it looks into itself, goes hmm ... I'm just adding thes numbers, and syntheizes a[i] + b[i] + c[i] + d[i] ... instead of all the temporaries. Thanks!

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  • creating QT gui using a thread in c++?

    - by rashid
    I am trying to create this QT gui using a thread but no luck. Below is my code. Problem is gui never shows up. /*INCLUDES HERE... .... */ using namespace std; struct mainStruct { int s_argc;<br> char ** s_argv; }; typedef struct mainStruct mas; void *guifunc(void * arg); int main(int argc, char * argv[]) { mas m;<br> m.s_argc = argc;<br> m.s_argv = argv;<br> pthread_t threadGUI; //start a new thread for gui int result = pthread_create(&threadGUI, NULL, guifunc, (void *) &m); if (result) {<br> printf("Error creating gui thread"); exit(0); } return 0; } void *guifunc(void * arg) { mas m = *(mas *)arg; QApplication app(m.s_argc,m.s_argv); //object instantiation<br> guiClass *gui = new guiClass(); //show gui<br> gui->show(); app.exec(); <br> }

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  • creating a QT gui using a thread in c++?

    - by rashid
    I am trying to create this QT gui using a thread but no luck. Below is my code. Problem is gui never shows up. But if i put QApplication app(m.s_argc,m.s_argv); //object instantiation guiClass *gui = new guiClass(); //show gui gui-show(); app.exec(); in main() then it works. /*INCLUDES HERE... .... */ using namespace std; struct mainStruct { int s_argc; char ** s_argv; }; typedef struct mainStruct mas; void *guifunc(void * arg); int main(int argc, char * argv[]) { mas m; m.s_argc = argc; m.s_argv = argv; pthread_t threadGUI; //start a new thread for gui int result = pthread_create(&threadGUI, NULL, guifunc, (void *) &m); if (result) { printf("Error creating gui thread"); exit(0); } return 0; } void *guifunc(void * arg) { mas m = *(mas *)arg; QApplication app(m.s_argc,m.s_argv); //object instantiation guiClass *gui = new guiClass(); //show gui gui-show(); app.exec(); }

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  • How to write a simple Lexer/Parser with antlr 2.7?

    - by Burkhard
    Hello, I have a complex grammar (in antlr 2.7) which I need to extend. Having never used antlr before, I wanted to write a very simple Lexer and Parser first. I found a very good explanation for antlr3 and tried to adapt it: header{ #include <iostream> using namespace std; } options { language="Cpp"; } class P2 extends Parser; /* This will be the entry point of our parser. */ eval : additionExp ; /* Addition and subtraction have the lowest precedence. */ additionExp : multiplyExp ( "+" multiplyExp | "-" multiplyExp )* ; /* Multiplication and addition have a higher precedence. */ multiplyExp : atomExp ( "*" atomExp | "/" atomExp )* ; /* An expression atom is the smallest part of an expression: a number. Or when we encounter parenthesis, we're making a recursive call back to the rule 'additionExp'. As you can see, an 'atomExp' has the highest precedence. */ atomExp : Number | "(" additionExp ")" ; /* A number: can be an integer value, or a decimal value */ number : ("0".."9")+ ("." ("0".."9")+)? ; /* We're going to ignore all white space characters */ protected ws : (" " | "\t" | "\r" | "\n") { newline(); } ; It does generate four files without errors: P2.cpp, P2.hpp, P2TokenTypes.hpp and P2TokenTypes.txt. But now what? How do I create a working programm with that? I tried to add these files to a VS2005-WinConsole-Project but it does not compile: p2.cpp(277) : fatal error C1010: unexpected end of file while looking for precompiled header. Did you forget to add '#include "stdafx.h"' to your source?

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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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  • Boost threading/mutexs, why does this work?

    - by Flamewires
    Code: #include <iostream> #include "stdafx.h" #include <boost/thread.hpp> #include <boost/thread/mutex.hpp> using namespace std; boost::mutex mut; double results[10]; void doubler(int x) { //boost::mutex::scoped_lock lck(mut); results[x] = x*2; } int _tmain(int argc, _TCHAR* argv[]) { boost::thread_group thds; for (int x = 10; x>0; x--) { boost::thread *Thread = new boost::thread(&doubler, x); thds.add_thread(Thread); } thds.join_all(); for (int x = 0; x<10; x++) { cout << results[x] << endl; } return 0; } Output: 0 2 4 6 8 10 12 14 16 18 Press any key to continue . . . So...my question is why does this work(as far as i can tell, i ran it about 20 times), producing the above output, even with the locking commented out? I thought the general idea was: in each thread: calculate 2*x copy results to CPU register(s) store calculation in correct part of array copy results back to main(shared) memory I would think that under all but perfect conditions this would result in some part of the results array having 0 values. Is it only copying the required double of the array to a cpu register? Or is it just too short of a calculation to get preempted before it writes the result back to ram? Thanks.

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