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  • Trouble move-capturing std::unique_ptr in a lambda using std::bind

    - by user2478832
    I'd like to capture a variable of type std::vector<std::unique_ptr<MyClass>> in a lambda expression (in other words, "capture by move"). I found a solution which uses std::bind to capture unique_ptr (http://stackoverflow.com/a/12744730/2478832) and decided to use it as a starting point. However, the most simplified version of the proposed code I could get doesn't compile (lots of template mistakes, it seems to try to call unique_ptr's copy constructor). #include <functional> #include <memory> std::function<void ()> a(std::unique_ptr<int>&& param) { return std::bind( [] (int* p) {}, std::move(param)); } int main() { a(std::unique_ptr<int>(new int())); } Can anybody point out what is wrong with this code? EDIT: tried changing the lambda to take a reference to unique_ptr, it still doesn't compile. #include <functional> #include <memory> std::function<void ()> a(std::unique_ptr<int>&& param) { return std::bind( [] (std::unique_ptr<int>& p) {}, // also as a const reference std::move(param)); } int main() { a(std::unique_ptr<int>(new int())); }

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  • Macro access to members of object where macro is defined

    - by Marc Grue
    Say I have a trait Foo that I instantiate with an initial value val foo = new Foo(6) // class Foo(i: Int) and I later call a second method that in turn calls myMacro foo.secondMethod(7) // def secondMethod(j: Int) = macro myMacro then, how can myMacro find out what my initial value of i (6) is? I didn't succeed with normal compilation reflection using c.prefix, c.eval(...) etc but instead found a 2-project solution: Project B: object CompilationB { def resultB(x: Int, y: Int) = macro resultB_impl def resultB_impl(c: Context)(x: c.Expr[Int], y: c.Expr[Int]) = c.universe.reify(x.splice * y.splice) } Project A (depends on project B): trait Foo { val i: Int // Pass through `i` to compilation B: def apply(y: Int) = CompilationB.resultB(i, y) } object CompilationA { def makeFoo(x: Int): Foo = macro makeFoo_impl def makeFoo_impl(c: Context)(x: c.Expr[Int]): c.Expr[Foo] = c.universe.reify(new Foo {val i = x.splice}) } We can create a Foo and set the i value either with normal instantiation or with a macro like makeFoo. The second approach allows us to customize a Foo at compile time in the first compilation and then in the second compilation further customize its response to input (i in this case)! In some way we get "meta-meta" capabilities (or "pataphysic"-capabilities ;-) Normally we would need to have foo in scope to introspect i (with for instance c.eval(...)). But by saving the i value inside the Foo object we can access it anytime and we could instantiate Foo anywhere: object Test extends App { import CompilationA._ // Normal instantiation val foo1 = new Foo {val i = 7} val r1 = foo1(6) // Macro instantiation val foo2 = makeFoo(7) val r2 = foo2(6) // "Curried" invocation val r3 = makeFoo(6)(7) println(s"Result 1 2 3: $r1 $r2 $r3") assert((r1, r2, r3) ==(42, 42, 42)) } My question Can I find i inside my example macros without this double compilation hackery?

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  • LINQ and Aggregate function

    - by vik20000in
    LINQ also provides with itself important aggregate function. Aggregate function are function that are applied over a sequence like and return only one value like Average, count, sum, Maximum etc…Below are some of the Aggregate functions provided with LINQ and example of their implementation. Count     int[] primeFactorsOf300 = { 2, 2, 3, 5, 5 };     int uniqueFactors = primeFactorsOf300.Distinct().Count();The below example provided count for only odd number.     int[] primeFactorsOf300 = { 2, 2, 3, 5, 5 };     int uniqueFactors = primeFactorsOf300.Distinct().Count(n => n%2 = 1);  Sum     int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };        double numSum = numbers.Sum();  Minimum      int minNum = numbers.Min(); Maximum      int maxNum = numbers.Max();Average      double averageNum = numbers.Average();  Aggregate      double[] doubles = { 1.7, 2.3, 1.9, 4.1, 2.9 };     double product = doubles.Aggregate((runningProduct, nextFactor) => runningProduct * nextFactor);  Vikram

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  • question about joGL (glTexImage2D)

    - by Nour
    Hi everybody I was trying to load a texture using joGL library but it seems that something is missing when using this method glTexImage2D at : IOStream wdis = new IOStream(fileName); wdis.skipBytes(18); int width = wdis.readIntW(); // dis.skipBytes(2); int height = wdis.readIntW(); // dis.skipBytes(2); wdis.skipBytes(28); byte buf[] = new byte[wdis.available()]; wdis.read(buf); wdis.close(); gl.glBindTexture(GL.GL_TEXTURE_2D, BMPtextures[index]); gl.glTexImage2D(GL.GL_TEXTURE_2D, 0, 3, width, height, 0, GL.GL_BGR, GL.GL_UNSIGNED_BYTE, buf); gl.glTexParameteri(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_MAG_FILTER, GL.GL_LINEAR); gl.glTexParameteri(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_MIN_FILTER, GL.GL_LINEAR); as IOStream is a class that extends DataInputStream it shows a message that glTexImage2D(int,int,int,int,int,int,int,int,byte[]) is not found at javax.media.opengl.GL I couldn't figure the problem her because it's an open source code and it seems to work perfectly with my friends but unfortunately not with me even though we are using the same library and the same JDK version what shall I do ??

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  • custom type face class by dinesh?

    - by dineshpeiris
    package typeface{ import flash.display.*; import flash.events.Event; import flash.filters.BitmapFilter; import flash.filters.BitmapFilterQuality; import flash.filters.BlurFilter; public class Main extends Sprite { private var typeSet:String="SEE > THINK > CREATE"; private var collectionSet:MovieClip; private var w:int = 1; public function Main():void { trace("start typeface application"); collectionSet = new MovieClip(); for (var n:int = 0; n < typeSet.length; n++) { var _x:int = 0 + (40 * n); var _y:int = 0; var Type:TypeCollector = new TypeCollector(_x, _y, stringToCharacter(typeSet, n), collectionSet); Type.addEventListener("action", actionHandler); } collectionSet.x = 100; collectionSet.y = (stage.stageHeight / 2) - 80; addChild(collectionSet); } private function actionHandler(event:Event):void { if (w == 16) { collectionSet.filters = [new BlurFilter(30, 30, BitmapFilterQuality.HIGH)]; removeChild(collectionSet); } w++; } public function stringToCharacter(str:String, n:int):String { if (str.length == 1) { return str; } return str.slice(n, n+1); } } } package typeface { import flash.display.*; import flash.events.Event; import flash.utils.Timer; import flash.events.TimerEvent; import flash.filters.BitmapFilter; import flash.filters.BitmapFilterQuality; import flash.filters.BlurFilter; import flash.events.EventDispatcher; public class TypeCollector extends EventDispatcher { private var TYPE_MC:typeMC; private var typeArray:Array = new Array("A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "1", "2", "3", "4", "5", "6", "7", "8", "9", "0", "<", ">"); private var character:String; private var num:int = 0; private var TypeTimer:Timer; private var _xNum:int; private var _yNum:int; private var movieClip:MovieClip; public function TypeCollector(_x:int, _y:int, char:String, movie:MovieClip) { var totalNum:int = typeArray.length; _xNum = _x; _yNum = _y; movieClip = movie; character = char; TypeTimer = new Timer(100, totalNum); TypeTimer.addEventListener("timer", TypeRoutTimer); TypeTimer.start(); } public function TypeRoutTimer(event:TimerEvent):void { CreateTypeFace(num, _xNum, _yNum, character); num++; } public function CreateTypeFace(num:int, _x:int, _y:int, character:String) { if (character == " ") { } else { if (TYPE_MC != null) { TYPE_MC.filters = [new BlurFilter(30, 30, BitmapFilterQuality.HIGH)]; movieClip.removeChild(TYPE_MC); } if (typeArray[num] == character) { TYPE_MC = new typeMC(); TYPE_MC.x = _x; TYPE_MC.y = _y; TYPE_MC.typeTF.text = typeArray[num]; TYPE_MC.filters = [new BlurFilter(5, 5, BitmapFilterQuality.HIGH)]; movieClip.addChild(TYPE_MC); dispatchEvent(new Event("action")); TypeTimer.stop(); } else { TYPE_MC = new typeMC(); TYPE_MC.x = _x; TYPE_MC.y = _y; TYPE_MC.typeTF.text = typeArray[num]; TYPE_MC.filters = [new BlurFilter(10, 10, BitmapFilterQuality.HIGH)]; movieClip.addChild(TYPE_MC); } } } } }

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  • IBasic Accumulator

    - by Tara
    I am trying to do an accumulator in IBasic for a college assignment and I have the general stuff down but I cannot get it to accumulate. The code is below. My question is how do I get it to accumulate and pass to the different module. I'm trying to calculate how many right answers the user gets. Also, i need to calculate the percentage of right answers. so if the user gets 9 out of 10 right theyed answer 90% right. 'October 15, 2009 ' 'Lab 7.5 Programming Challenge 1 - Average Test Scores ' 'This is a dice game ' declare main() declare inputName(name:string) declare getAnswer(num1:int, num2:int) declare getResult(num1:int, num2:int, answer:int) declare avgRight(getRight:int) declare printInfo(name:string, getRight:int, averege:float) openconsole main() do:until inkey$<>"" closeconsole end sub main() def name:string def num1, num2, answer, total, getRight:int def averege:float inputName (name) getRight = 0 For counter = 1 to 10 getRight = getAnswer(num1, num2) getRight = getRight + 1 next counter average = avgRight (getRight) printInfo(Name, getRight, average) end sub inputName (name) Input "Please enter your name: " ,name return sub getAnswer(num1, num2) def answer, getRight:int num1 = rnd (10) + 1 num2 = rnd (10) + 1 Print num1, "+ " ,num2 Input "What is the answer to the equation? " ,answer getRight = getResult(num1, num2, answer) return getRight sub getResult(num1, num2, answer) def getRight:int if answer = num1 + num2 getRight = 1 else getRight = 0 endif return getRight sub avgRight(getRight) def average:float average = getRight / 10 return average sub printInfo(name, getRight, averege) Print "The students name is: " ,name Print "The number right is: " ,getRight Print Using ("&##.#&", "The average right is " ,averege * 100, "%") return

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  • Pointer to 2D array. Why does this example work?

    - by Louise
    I have this code example, but I don't understand why changing the values in the array inside outputUsingArray() are changing the original array. I would have expected changing the values of the array in outputUsingArray() would only be for a local copy of the array. Why isn't that so? However, this is the behaviour I would like, but I don't understand why it work. #include <stdlib.h> #include <stdio.h> void outputUsingArray(int array[][4], int n_rows, int n_cols) { int i, j; printf("Output Using array\n"); for (i = 0; i < n_rows; i++) { for (j = 0; j < n_cols; j++) { // Either can be used. //printf("%2d ", array[i][j] ); printf("%2d ", *(*(array+i)+j)); } printf("\n"); } printf("\n"); array[0][0] = 100; array[2][3] = 200; } void outputUsingPointer(int (*array)[4], int n_rows, int n_cols) { int i, j; printf("Output Using Pointer to Array i.e. int (*array)[4]\n"); for (i = 0; i < n_rows; i++) { for (j = 0; j < n_cols; j++) { printf("%2d ", *(*(array+i) + j )); } printf("\n"); } printf("\n"); } int main() { int array[3][4] = { { 0, 1, 2, 3 }, { 4, 5, 6, 7 }, { 8, 9, 10, 11 } }; outputUsingPointer((int (*)[4])array, 3, 4); outputUsingArray(array, 3, 4); printf("0,0: %i\n", array[0][0]); printf("2,3: %i\n", array[2][3]); return 0; }

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  • abstract data type list. . .

    - by aldrin
    A LIST is an ordered collection of items where items may be inserted anywhere in the list. Implement a LIST using an array as follows: struct list { int *items; // pointer to the array int size; // actual size of the array int count; // number of items in the array }; typedef struct list *List; // pointer to the structure Implement the following functions: a) List newList(int size); - will create a new List and return its pointer. Allocate space for the structure, allocate space for the array, then initialize size and count, return the pointer. b) void isEmpty(List list); c) void display(List list); d) int contains(List list, int item); e) void remove(List list, int i) ; f) void insertAfter(List list,int item, int i); g) void addEnd(List list,int item) - add item at the end of the list – simply store the data at position count, then increment count. If the array is full, allocate an array twice as big as the original. count = 5 size = 10 0 1 2 3 4 5 6 7 8 9 5 10 15 20 30 addEnd(list,40) will result to count = 6 size = 10 0 1 2 3 4 5 6 7 8 9 5 10 15 20 30 40 h) void addFront(List list,int item) - shift all elements to the right so that the item can be placed at position 0, then increment count. Bonus: if the array is full, allocate an array twice as big as the original. count = 5 size = 10 0 1 2 3 4 5 6 7 8 9 5 10 15 20 30 addFront(list,40) will result to count = 6 size = 10 0 1 2 3 4 5 6 7 8 9 40 5 10 15 20 30 i) void removeFront(List list) - shift all elements to the left and decrement count; count = 6 size = 10 0 1 2 3 4 5 6 7 8 9 40 5 10 15 20 30 removeFront(list) will result to count = 5 size = 10 0 1 2 3 4 5 6 7 8 9 5 10 15 20 30 j) void remove(List list,int item) - get the index of the item in the list and then shift all elements to the count = 6 size = 10 0 1 2 3 4 5 6 7 8 9 40 5 10 15 20 30 remove(list,10) will result to count = 5 size = 10 0 1 2 3 4 5 6 7 8 9 40 5 15 20 30

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  • object_getInstanceVariable works for float, int, bool, but not for double?

    - by Russel West
    I've got object_getInstanceVariable to work as here however it seems to only work for floats, bools and ints not doubles. I do suspect I'm doing something wrong but I've been going in circles with this. float myFloatValue; float someFloat = 2.123f; object_getInstanceVariable(self, "someFloat", (void*)&myFloatValue); works, and myFloatValue = 2.123 but when I try double myDoubleValue; double someDouble = 2.123f; object_getInstanceVariable(self, "someDouble", (void*)&myDoubleValue); i get myDoubleValue = 0. If I try to set myDoubleValue before the function eg. double myDoubleValue = 1.2f, the value is unchanged when I read it after the object_getInstanceVariable call. setting myIntValue to some other value before the getinstancevar function above returns 2 as it should, ie. it has been changed. then I tried Ivar tmpIvar = object_getInstanceVariable(self, "someDouble", (void*)&myDoubleValue); if i do ivar_getName(tmpIvar) i get "someDouble", but myDoubuleValue = 0 still! then i try ivar_getTypeEncoding(tmpIvar) and i get "d" as it should be. So to summarize, if typeEncoding = float, it works, if it is a double, the result is not set but it correctly reads the variable and the return value (Ivar) is also correct. I must be doing something basic wrong that I cant see so I'd appreciate if someone could point it out.

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  • collect2: ld returned 1 exit status error in Xcode

    - by user573949
    Hello, Im getting the error Command /Developer/usr/bin/gcc-4.2 failed with exit code 1 and when the full log is opened, the error is more accurately listed as: collect2: ld returned 1 exit status from this simple Cocoa script: #import "Controller.h" @implementation Controller int skillcheck (int level, int modifer, int difficulty) { if (level + modifer >= difficulty) { return 1; } if (level + modifer <= difficulty) { return 0; } } int main () { skillcheck(10, 2, 10); } @end the .h file is this: // // Controller.h // // Created by Duo Oratar on 15/01/2011. // Copyright 2011 __MyCompanyName__. All rights reserved. // #import <Cocoa/Cocoa.h> @interface Controller : NSObject { int skillcheck; int contestcheck; } @end and no line was specified that the error came from, does anyone know what the source of this error is, and more importantly, how to fix it? EDIT: I removed the class so now I have this: // // Controller.m // // Created by Duo Oratar on 15/01/2011. // Copyright 2011 __MyCompanyName__. All rights reserved. // #import "Controller.h" int skillcheck (int level, int modifer, int difficulty) { if (level + modifer >= difficulty) { return 1; } if (level + modifer <= difficulty) { return 0; } } int main () { skillcheck(10, 2, 10); } and for the .h file: // // Controller.h // // Created by Duo Oratar on 15/01/2011. // Copyright 2011 __MyCompanyName__. All rights reserved. // #import <Cocoa/Cocoa.h> and the log says: (thanks to the guy who said how to open it) Ld build/Debug/Calculator.app/Contents/MacOS/Calculator normal x86_64 cd /Users/kids/Desktop/Calculator setenv MACOSX_DEPLOYMENT_TARGET 10.6 /Developer/usr/bin/gcc-4.2 -arch x86_64 -isysroot /Developer/SDKs/MacOSX10.6.sdk -L/Users/kids/Desktop/Calculator/build/Debug -F/Users/kids/Desktop/Calculator/build/Debug -filelist /Users/kids/Desktop/Calculator/build/Calculator.build/Debug/Calculator.build/Objects-normal/x86_64/Calculator.LinkFileList -mmacosx-version-min=10.6 -framework Cocoa -o /Users/kids/Desktop/Calculator/build/Debug/Calculator.app/Contents/MacOS/Calculator ld: duplicate symbol _main in /Users/kids/Desktop/Calculator/build/Calculator.build/Debug/Calculator.build/Objects-normal/x86_64/Controller.o and /Users/kids/Desktop/Calculator/build/Calculator.build/Debug/Calculator.build/Objects-normal/x86_64/main.o collect2: ld returned 1 exit status Command /Developer/usr/bin/gcc-4.2 failed with exit code 1 ld: duplicate symbol _main in /Users/kids/Desktop/Calculator/build/Calculator.build/Debug/Calculator.build/Objects-normal/x86_64/Controller.o and /Users/kids/Desktop/Calculator/build/Calculator.build/Debug/Calculator.build/Objects-normal/x86_64/main.o Command /Developer/usr/bin/gcc-4.2 failed with exit code 1

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  • unsigned char* buffer (FreeType2 Bitmap) to System::Drawing::Bitmap.

    - by Dennis Roche
    Hi, I'm trying to convert a FreeType2 bitmap to a System::Drawing::Bitmap in C++/CLI. FT_Bitmap has a unsigned char* buffer that contains the data to write. I have got somewhat working save it disk as a *.tga, but when saving as *.bmp it renders incorrectly. I believe that the size of byte[] is incorrect and that my data is truncated. Any hints/tips/ideas on what is going on here would be greatly appreciated. Links to articles explaining byte layout and pixel formats etc. would be helpful. Thanks!! C++/CLI code. FT_Bitmap *bitmap = &face->glyph->bitmap; int width = (face->bitmap->metrics.width / 64); int height = (face->bitmap->metrics.height / 64); // must be aligned on a 32 bit boundary or 4 bytes int depth = 8; int stride = ((width * depth + 31) & ~31) >> 3; int bytes = (int)(stride * height); // as *.tga void *buffer = bytes ? malloc(bytes) : NULL; if (buffer) { memset(buffer, 0, bytes); for (int i = 0; i < glyph->rows; ++i) memcpy((char *)buffer + (i * width), glyph->buffer + (i * glyph->pitch), glyph->pitch); WriteTGA("Test.tga", buffer, width, height); } // as *.bmp array<Byte>^ values = gcnew array<Byte>(bytes); Marshal::Copy((IntPtr)glyph->buffer, values, 0, bytes); Bitmap^ systemBitmap = gcnew Bitmap(width, height, PixelFormat::Format24bppRgb); // create bitmap data, lock pixels to be written. BitmapData^ bitmapData = systemBitmap->LockBits(Rectangle(0, 0, width, height), ImageLockMode::WriteOnly, bitmap->PixelFormat); Marshal::Copy(values, 0, bitmapData->Scan0, bytes); systemBitmap->UnlockBits(bitmapData); systemBitmap->Save("Test.bmp"); Reference, FT_Bitmap typedef struct FT_Bitmap_ { int rows; int width; int pitch; unsigned char* buffer; short num_grays; char pixel_mode; char palette_mode; void* palette; } FT_Bitmap; Reference, WriteTGA bool WriteTGA(const char *filename, void *pxl, uint16 width, uint16 height) { FILE *fp = NULL; fopen_s(&fp, filename, "wb"); if (fp) { TGAHeader header; memset(&header, 0, sizeof(TGAHeader)); header.imageType = 3; header.width = width; header.height = height; header.depth = 8; header.descriptor = 0x20; fwrite(&header, sizeof(header), 1, fp); fwrite(pxl, sizeof(uint8) * width * height, 1, fp); fclose(fp); return true; } return false; } Update FT_Bitmap *bitmap = &face->glyph->bitmap; // stride must be aligned on a 32 bit boundary or 4 bytes int depth = 8; int stride = ((width * depth + 31) & ~31) >> 3; int bytes = (int)(stride * height); target = gcnew Bitmap(width, height, PixelFormat::Format8bppIndexed); // create bitmap data, lock pixels to be written. BitmapData^ bitmapData = target->LockBits(Rectangle(0, 0, width, height), ImageLockMode::WriteOnly, target->PixelFormat); array<Byte>^ values = gcnew array<Byte>(bytes); Marshal::Copy((IntPtr)bitmap->buffer, values, 0, bytes); Marshal::Copy(values, 0, bitmapData->Scan0, bytes); target->UnlockBits(bitmapData);

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  • C++ Beginner - Trouble using classes inside of classes

    - by Francisco P.
    Hello, I am working on a college project, where I have to implement a simple Scrabble game. I have a player class (containing a Score and the player's hand, in the form of a std::string, and a score class (containing a name and numeric (int) score). One of Player's member-functions is Score getScore(), which returns a Score object for that player. However, I get the following error on compile time: player.h(27) : error C2146: syntax error : missing ';' before identifier 'getScore' player.h(27) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int player.h(27) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int player.h(27) : warning C4183: 'getScore': missing return type; assumed to be a member function returning 'int' player.h(35) : error C2146: syntax error : missing ';' before identifier '_score' player.h(35) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int player.h(35) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int Here's lines 27 and 35, respectively: Score getScore(); //defined as public (...) Score _score; //defined as private I get that the compiler is having trouble recognizing Score as a valid type... But why? I have correctly included Score.h at the beginning of player.h: #include "Score.h" #include "Deck.h" #include <string> I have a default constructor for Score defined in Score.h: Score(); //score.h //score.cpp Score::Score() { _name = ""; _points = 0; } Any input would be appreciated! Thanks for your time, Francisco EDIT: As requested, score.h and player.h: http://pastebin.com/3JzXP36i http://pastebin.com/y7sGVZ4A

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  • Multiple constructors in C

    - by meepz
    Hello, I am making a string class in C as a homework and I was wondering how I can make multiple constructors with the same name given the parameter. The commented out area is what I tried to do with results from a few searches but that gives me errors. Pretty much I have some cases where I want to create my new string without any parameter then in other cases create a string with a pointer to character. Here is mystring.h #include <stdio.h> #include <stdlib.h> typedef struct mystring { char * c; int length; int (*sLength)(void * s); char (*charAt)(void * s, int i); int (*compareTo)(void * s1, void * s2); struct mystring * (*concat)(void * s1, void * s2); struct mystring * (*subString)(void * s, int begin, int end); void (*printS)(void * s); } string_t; typedef string_t * String; String newString(char * c); String newString2(); int slength(void * s); char charat(void * S, int i); int compareto(void * s1, void * s2); String concat(void * s1, void * s2); String substring(void * S, int begin, int end); void printstring(void * s); And here is mystring.c #include "mystring.h" String newString(){ } String newString(char * input){ //String newString::newString(char * input) { String s; s = (string_t *) malloc(sizeof(string_t)); s->c = (char *) malloc(sizeof(char) * 20); int i = 0; if (input == NULL){ s->c[0] = '\0'; return s; } while (input[i] != '\0') { s->c[i] = input[i]; i++; } //functions s->sLength = slength; s->charAt = charat; s->compareTo = compareto; s->concat = concat; s->subString = substring; s->printS = printstring; return s; }

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  • Query on simple C++ threadpool implementation

    - by ticketman
    Stackoverflow has been a tremendous help to me and I'd to give something back to the community. I have been implementing a simple threadpool using the tinythread C++ portable thread library, using what I have learnt from Stackoverflow. I am new to thread programming, so not that comfortable with mutexes, etc. I have a question best asked after presenting the code (which runs quite well under Linux): // ThreadPool.h class ThreadPool { public: ThreadPool(); ~ThreadPool(); // Creates a pool of threads and gets them ready to be used void CreateThreads(int numOfThreads); // Assigns a job to a thread in the pool, but doesn't start the job // Each SubmitJob call will use up one thread of the pool. // This operation can only be undone by calling StartJobs and // then waiting for the jobs to complete. On completion, // new jobs may be submitted. void SubmitJob( void (*workFunc)(void *), void *workData ); // Begins execution of all the jobs in the pool. void StartJobs(); // Waits until all jobs have completed. // The wait will block the caller. // On completion, new jobs may be submitted. void WaitForJobsToComplete(); private: enum typeOfWorkEnum { e_work, e_quit }; class ThreadData { public: bool ready; // thread has been created and is ready for work bool haveWorkToDo; typeOfWorkEnum typeOfWork; // Pointer to the work function each thread has to call. void (*workFunc)(void *); // Pointer to work data void *workData; ThreadData() : ready(false), haveWorkToDo(false) { }; }; struct ThreadArgStruct { ThreadPool *threadPoolInstance; int threadId; }; // Data for each thread ThreadData *m_ThreadData; ThreadPool(ThreadPool const&); // copy ctor hidden ThreadPool& operator=(ThreadPool const&); // assign op. hidden // Static function that provides the function pointer that a thread can call // By including the ThreadPool instance in the void * parameter, // we can use it to access other data and methods in the ThreadPool instance. static void ThreadFuncWrapper(void *arg) { ThreadArgStruct *threadArg = static_cast<ThreadArgStruct *>(arg); threadArg->threadPoolInstance->ThreadFunc(threadArg->threadId); } // The function each thread calls void ThreadFunc( int threadId ); // Called by the thread pool destructor void DestroyThreadPool(); // Total number of threads available // (fixed on creation of thread pool) int m_numOfThreads; int m_NumOfThreadsDoingWork; int m_NumOfThreadsGivenJobs; // List of threads std::vector<tthread::thread *> m_ThreadList; // Condition variable to signal each thread has been created and executing tthread::mutex m_ThreadReady_mutex; tthread::condition_variable m_ThreadReady_condvar; // Condition variable to signal each thread to start work tthread::mutex m_WorkToDo_mutex; tthread::condition_variable m_WorkToDo_condvar; // Condition variable to signal the main thread that // all threads in the pool have completed their work tthread::mutex m_WorkCompleted_mutex; tthread::condition_variable m_WorkCompleted_condvar; }; cpp file: // // ThreadPool.cpp // #include "ThreadPool.h" // This is the thread function for each thread. // All threads remain in this function until // they are asked to quit, which only happens // when terminating the thread pool. void ThreadPool::ThreadFunc( int threadId ) { ThreadData *myThreadData = &m_ThreadData[threadId]; std::cout << "Hello world: Thread " << threadId << std::endl; // Signal that this thread is ready m_ThreadReady_mutex.lock(); myThreadData->ready = true; m_ThreadReady_condvar.notify_one(); // notify the main thread m_ThreadReady_mutex.unlock(); while(true) { //tthread::lock_guard<tthread::mutex> guard(m); m_WorkToDo_mutex.lock(); while(!myThreadData->haveWorkToDo) // check for work to do m_WorkToDo_condvar.wait(m_WorkToDo_mutex); // if no work, wait here myThreadData->haveWorkToDo = false; // need to do this before unlocking the mutex m_WorkToDo_mutex.unlock(); // Do the work switch(myThreadData->typeOfWork) { case e_work: std::cout << "Thread " << threadId << ": Woken with work to do\n"; // Do work myThreadData->workFunc(myThreadData->workData); std::cout << "#Thread " << threadId << ": Work is completed\n"; break; case e_quit: std::cout << "Thread " << threadId << ": Asked to quit\n"; return; // ends the thread } // Now to signal the main thread that my work is completed m_WorkCompleted_mutex.lock(); m_NumOfThreadsDoingWork--; // Unsure if this 'if' would make the program more efficient // if(NumOfThreadsDoingWork == 0) m_WorkCompleted_condvar.notify_one(); // notify the main thread m_WorkCompleted_mutex.unlock(); } } ThreadPool::ThreadPool() { m_numOfThreads = 0; m_NumOfThreadsDoingWork = 0; m_NumOfThreadsGivenJobs = 0; } ThreadPool::~ThreadPool() { if(m_numOfThreads) { DestroyThreadPool(); delete [] m_ThreadData; } } void ThreadPool::CreateThreads(int numOfThreads) { // Check a thread pool has already been created if(m_numOfThreads > 0) return; m_NumOfThreadsGivenJobs = 0; m_NumOfThreadsDoingWork = 0; m_numOfThreads = numOfThreads; m_ThreadData = new ThreadData[m_numOfThreads]; ThreadArgStruct threadArg; for(int i=0; i<m_numOfThreads; ++i) { threadArg.threadId = i; threadArg.threadPoolInstance = this; // Creates the thread and save in a list so we can destroy it later m_ThreadList.push_back( new tthread::thread( ThreadFuncWrapper, (void *)&threadArg ) ); // It takes a little time for a thread to get established. // Best wait until it gets established before creating the next thread. m_ThreadReady_mutex.lock(); while(!m_ThreadData[i].ready) // Check if thread is ready m_ThreadReady_condvar.wait(m_ThreadReady_mutex); // If not, wait here m_ThreadReady_mutex.unlock(); } } // Adds a job to the batch, but doesn't start the job void ThreadPool::SubmitJob(void (*workFunc)(void *), void *workData) { // Check that the thread pool has been created if(!m_numOfThreads) return; if(m_NumOfThreadsGivenJobs >= m_numOfThreads) return; m_ThreadData[m_NumOfThreadsGivenJobs].workFunc = workFunc; m_ThreadData[m_NumOfThreadsGivenJobs].workData = workData; std::cout << "Submitted job " << m_NumOfThreadsGivenJobs << std::endl; m_NumOfThreadsGivenJobs++; } void ThreadPool::StartJobs() { // Check that the thread pool has been created // and some jobs have been assigned if(!m_numOfThreads || !m_NumOfThreadsGivenJobs) return; // Set 'haveworkToDo' flag for all threads m_WorkToDo_mutex.lock(); for(int i=0; i<m_NumOfThreadsGivenJobs; ++i) m_ThreadData[i].haveWorkToDo = true; m_NumOfThreadsDoingWork = m_NumOfThreadsGivenJobs; // Reset this counter so we can resubmit jobs later m_NumOfThreadsGivenJobs = 0; // Notify all threads they have work to do m_WorkToDo_condvar.notify_all(); m_WorkToDo_mutex.unlock(); } void ThreadPool::WaitForJobsToComplete() { // Check that a thread pool has been created if(!m_numOfThreads) return; m_WorkCompleted_mutex.lock(); while(m_NumOfThreadsDoingWork > 0) // Check if all threads have completed their work m_WorkCompleted_condvar.wait(m_WorkCompleted_mutex); // If not, wait here m_WorkCompleted_mutex.unlock(); } void ThreadPool::DestroyThreadPool() { std::cout << "Ask threads to quit\n"; m_WorkToDo_mutex.lock(); for(int i=0; i<m_numOfThreads; ++i) { m_ThreadData[i].haveWorkToDo = true; m_ThreadData[i].typeOfWork = e_quit; } m_WorkToDo_condvar.notify_all(); m_WorkToDo_mutex.unlock(); // As each thread terminates, catch them here for(int i=0; i<m_numOfThreads; ++i) { tthread::thread *t = m_ThreadList[i]; // Wait for thread to complete t->join(); } m_numOfThreads = 0; } Example of usage: (this calculates pi-squared/6) struct CalculationDataStruct { int inputVal; double outputVal; }; void LongCalculation( void *theSums ) { CalculationDataStruct *sums = (CalculationDataStruct *)theSums; int terms = sums->inputVal; double sum; for(int i=1; i<terms; i++) sum += 1.0/( double(i)*double(i) ); sums->outputVal = sum; } int main(int argc, char** argv) { int numThreads = 10; // Create pool ThreadPool threadPool; threadPool.CreateThreads(numThreads); // Create thread workspace CalculationDataStruct sums[numThreads]; // Set up jobs for(int i=0; i<numThreads; i++) { sums[i].inputVal = 3000*(i+1); threadPool.SubmitJob(LongCalculation, &sums[i]); } // Run the jobs threadPool.StartJobs(); threadPool.WaitForJobsToComplete(); // Print results for(int i=0; i<numThreads; i++) std::cout << "Sum of " << sums[i].inputVal << " terms is " << sums[i].outputVal << std::endl; return 0; } Question: In the ThreadPool::ThreadFunc method, would better performance be obtained if the following if statement if(NumOfThreadsDoingWork == 0) was included? Also, I'd be grateful of criticisms and ways to improve the code. At the same time, I hope the code is of use to others.

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  • Exporting to XML, including embedded classes

    - by Andy
    I have an object config which has some properties. I can export this ok, however, it also has an ArrayList which relates to embedded classes which I can't get to appear when I export to XML. Any pointers would be helpful. Export Method public String exportXML(config conf, String path) { String success = ""; try { FileOutputStream fstream = new FileOutputStream(path); try { XMLEncoder ostream = new XMLEncoder(fstream); try { ostream.writeObject(conf); ostream.flush(); } finally { ostream.close(); } } finally { fstream.close(); } } catch (Exception ex) { success = ex.getLocalizedMessage(); } return success; } Config Class (some detail stripped to keep size down) public class config { protected String author = ""; protected String website = ""; private ArrayList questions = new ArrayList(); public config(){ } public void addQuestion(String name) { questions.add(new question(questions.size(), name)); } public void removeQuestion(int id) { questions.remove(id); for (int c = 0; c <= questions.size(); c++) { question q = (question) (questions.get(id)); q.setId(c); } questions.trimToSize(); } public config.question getQuestion(int id){ return (question)questions.get(id); } /** * There can be multiple questions per config. * Questions store all the information regarding what questions are * asked of the user, including images, descriptions, and answers. */ public class question { protected int id; protected String title; protected ArrayList answers; public question(int id, String title) { this.id = id; this.title = title; } public int getId() { return id; } public void setId(int id) { this.id = id; } public void addAnswer(String name) { answers.add(new answer(answers.size(), name)); } public void removeAnswer(int id) { answers.remove(id); for (int c = 0; c <= answers.size(); c++) { answer a = (answer) (answers.get(id)); a.setId(c); } answers.trimToSize(); } public config.question.answer getAnswer(int id){ return (answer)answers.get(id); } public class answer { protected int id; protected String title; public answer(int id, String title) { this.id = id; this.title = title; } public int getId() { return id; } public void setId(int id) { this.id = id; } } } } Resultant XML File <?xml version="1.0" encoding="UTF-8"?> <java version="1.6.0_18" class="java.beans.XMLDecoder"> <object class="libConfig.config"> <void property="appName"> <string>xxx</string> </void> <void property="author"> <string>Andy</string> </void> <void property="website"> <string>www.example.com/dsx.xml</string> </void> </object> </java>

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  • Get aspect ratio of a monitor

    - by Alexander Stalt
    I want to get aspect ratio of a monitor as two digits : width and height. For example 4 and 3, 5 and 4, 16 and 9. I wrote some code for that task. Maybe it is any easier way to do that ? For example, some library function =\ /// <summary> /// Aspect ratio. /// </summary> public struct AspectRatio { int _height; /// <summary> /// Height. /// </summary> public int Height { get { return _height; } } int _width; /// <summary> /// Width. /// </summary> public int Width { get { return _width; } } /// <summary> /// Ctor. /// </summary> /// <param name="height">Height of aspect ratio.</param> /// <param name="width">Width of aspect ratio.</param> public AspectRatio(int height, int width) { _height = height; _width = width; } } public sealed class Aux { /// <summary> /// Get aspect ratio. /// </summary> /// <returns>Aspect ratio.</returns> public static AspectRatio GetAspectRatio() { int deskHeight = Screen.PrimaryScreen.Bounds.Height; int deskWidth = Screen.PrimaryScreen.Bounds.Width; int gcd = GCD(deskWidth, deskHeight); return new AspectRatio(deskHeight / gcd, deskWidth / gcd); } /// <summary> /// Greatest Common Denominator (GCD). Euclidean algorithm. /// </summary> /// <param name="a">Width.</param> /// <param name="b">Height.</param> /// <returns>GCD.</returns> static int GCD(int a, int b) { return b == 0 ? a : GCD(b, a % b); } }

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  • get cells odf a JTable

    - by tuxou
    hi how to display a row of a jtable in a from of JTextField when click on the row, ( I need this to edit the data base from the JTable ) My table model static class TableDataModel extends AbstractTableModel { private List nomColonnes; private List tableau; public TableDataModel(List nomColonnes, List tableau){ this.nomColonnes = nomColonnes; majDonnees(tableau); } public void majDonnees(List nouvellesDonnees){ this.tableau = nouvellesDonnees; fireTableDataChanged(); } public int getRowCount(){ return tableau.size(); } public int getColumnCount(){ return nomColonnes.size(); } public Object getValueAt(int row, int col){ return ((ArrayList)( tableau.get(row))).get(col); } public String getColumnName(int col){ return nomColonnes.get(col).toString(); } public Class getColumnClass(int c) { return getValueAt(0,c).getClass(); } public boolean isCellEditable(int row, int col){ return true; } public void setValueAt(Object value, int row, int col) { ((List)tableau.get(row)).set(col,value); fireTableCellUpdated(row, col); //i suppose i should update the database here } }

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  • using cin and cout in textmate [migrated]

    - by That Guy
    I am usually a Java programmer, and have used textmate for that almost exclusively, but lately I started using C++ with it. but when i use even the most basic programs and incorporate the cin keyword, and run the program, I dont get an oppurtunity to put in anything during runtime and sometimes it inserts random values by itself! for example, if i ran this in textmate: #include <iostream> int stonetolb(int); int main() { using namespace std; int stone; cout << "enter the weight in stone"; cin >> stone; int pounds = stonetolb(stone); cout << stone << "stone = "; cout << pounds <<" pounds."; return 0; } int stonetolb(int sts) { return 14 * sts; } I would come out with the output: enter the weight in stone32767stone = 458738 pounds. Why is this happening, and how do I stop it?

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  • VERY simple C program won't compile with VC 64

    - by Paperflyer
    Here is a very simple C program: #include <stdio.h> int main (int argc, char *argv[]) { printf("sizeof(short) = %d\n",(int)sizeof(short)); printf("sizeof(int) = %d\n",(int)sizeof(int)); printf("sizeof(long) = %d\n",(int)sizeof(long)); printf("sizeof(long long) = %d\n",(int)sizeof(long long)); printf("sizeof(float) = %d\n",(int)sizeof(float)); printf("sizeof(double) = %d\n",(int)sizeof(double)); return 0; } While it compiles fine on Win32 (command line: cl main.c), it does not using the Win64 compiler ("c:\Program Files(x86)\Microsoft Visual Studio 9.0\VC\bin\amd64\cl.exe" main.c). Specifically, it sais "error LNK2019: unresolved external symbol printf referenced in function main". As far as I understand this, it can not link to printf, right? Obviously, I have Microsoft Visual C++ Compiler 2008 (Standard enu) x86 and x64 installed and am using the 64-bit flavor of Windows (7). What is the problem here?

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  • Trying to use boost lambda, but my code won't compile

    - by hamishmcn
    Hi, I am trying to use boost lambda to avoid having to write trivial functors. For example, I want to use the lambda to access a member of a struct or call a method of a class, eg: #include <vector> #include <utility> #include <algorithm> #include <boost/lambda/lambda.hpp> using namespace std; using namespace boost::lambda; vector< pair<int,int> > vp; vp.push_back( make_pair<int,int>(1,1) ); vp.push_back( make_pair<int,int>(3,2) ); vp.push_back( make_pair<int,int>(2,3) ); sort(vp.begin(), vp.end(), _1.first > _2.first ); When I try and compile this I get the following errors: error C2039: 'first' : is not a member of 'boost::lambda::lambda_functor<T>' with [ T=boost::lambda::placeholder<1> ] error C2039: 'first' : is not a member of 'boost::lambda::lambda_functor<T>' with [ T=boost::lambda::placeholder<2> ] Since vp contains pair<int,int> I thought that _1.first should work. What I am doing wrong?

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  • An unhandled exception of type 'System.StackOverflowException' occurred in System.Windows.Forms.dll

    - by Tanner
    OK, Im trying to highlight keywords in a richtextbox, the problem is I've got the code to highlight only the visible text on textChanged event,so I tryed putting the code in the richtextbox VScroll, so when I scrolled up it would highlight the text that wasn't visible before, but every time I start to scroll I get this error: "An unhandled exception of type 'System.StackOverflowException' occurred in System.Windows.Forms.dll" Does any one know why? Or maybe a way I could highlight the words while scrolling? Thanks, Tanner. int selectionstart = richTextBox1.Selectionstart; int topIndex = richTextBox1.GetCharIndexFromPosition(new Point(1, 1));//This is where I get the error. int bottomIndex = richTextBox1.GetCharIndexFromPosition(new Point(1, richTextBox1.Height - 1)); int topLine = richTextBox1.GetLineFromCharIndex(topIndex); int bottomLine = richTextBox1.GetLineFromCharIndex(bottomIndex); int start = richTextBox1.GetFirstCharIndexFromLine(topLine); int end = richTextBox1.GetFirstCharIndexFromLine(bottomLine); int numLinesDisplayed = (bottomLine - topLine) + 2; richTextBox1.Focus(); richTextBox1.Select(start, end);

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  • The MYSTERY SPIRAL

    - by CVS26
    Problem statement: Given a integer N, print N*N numbers in a N x N spiral Detailed problem description: http://2600hertz.wordpress.com/2010/03/20/the-mystery-spiral/ Solution: Recently posted the following code. (managed to compress it into as few as 99 lines...) //File : spiral.c // //INPUT : Size of spiral (N) //OUTPUT : Numbers printed in a N x N spiral #include <stdio.h> #include <conio.h> #include <stdlib.h> void main() { int N; clrscr(); //get input no. N printf("\nEnter size of Matrix: "); scanf("%d",&N); //Allocate reqd. memory int* matrix_ptr= (int*)malloc(N*N); //Filling the Matrix spirally int curr_val=N*N; int* curr_ptr=matrix_ptr; int curr_level=N; while(curr_level>1) { //curr_level-1 elements horizontally //from left to right for(int x=0;x<curr_level-1;x++) { *curr_ptr=curr_val; curr_val--; curr_ptr++; } //curr_level-1 elements vertically //from top to bottom for(int y=0;y<curr_level-1;y++) { *curr_ptr=curr_val; curr_val--; curr_ptr+=N; } //curr_level-1 elements horizontally //from right to left for(int z=0;z<curr_level-1;z++) { *curr_ptr=curr_val; curr_val--; curr_ptr--; } //curr_level-1 element vertically //from bottom to top for(int w=0;w<curr_level-1;w++) { *curr_ptr=curr_val; curr_val--; curr_ptr-=N; } //Next curr_ptr+=N+1; curr_level-=2; } *curr_ptr=curr_val; //routine to print the matrix printf("\n\n\n\n\n"); for( int i=0;i<N;i++) { for( int j=0;j<N;j++) { printf("%d\t",*(matrix_ptr+(i*N+j))); } printf("\n"); } getch(); } Please comment on further optimisations (if any)...

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  • Can I pass a querystring that translates to a List<int> on the server?

    - by Denis Hoctor
    Hi all, I'm writing a Google Maps app that requests data from the server using jQuery's $.ajax() to send the request to my MVC Contoller. This control expects a List for the category types. What should the querystring look like for this? I've tried http://localhost:9090/mapamenities?amenityTypes=1,5 http://localhost:9090/mapamenities?amenityTypes=[1,5] with no luck. The SearchRquest attribute I'm trying to bind to is public List AmenityTypes { get; set; } Thanks Denis

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  • How can I convert this C Calendaer Code into a Objective-C syntax and have it work with matrixes

    - by Alec Niemy
    #define TRUE 1 #define FALSE 0 int days_in_month[]={0,31,28,31,30,31,30,31,31,30,31,30,31}; char *months[]= { " ", "\n\n\nJanuary", "\n\n\nFebruary", "\n\n\nMarch", "\n\n\nApril", "\n\n\nMay", "\n\n\nJune", "\n\n\nJuly", "\n\n\nAugust", "\n\n\nSeptember", "\n\n\nOctober", "\n\n\nNovember", "\n\n\nDecember" }; int inputyear(void) { int year; printf("Please enter a year (example: 1999) : "); scanf("%d", &year); return year; } int determinedaycode(int year) { int daycode; int d1, d2, d3; d1 = (year - 1.)/ 4.0; d2 = (year - 1.)/ 100.; d3 = (year - 1.)/ 400.; daycode = (year + d1 - d2 + d3) %7; return daycode; } int determineleapyear(int year) { if(year% 4 == FALSE && year%100 != FALSE || year%400 == FALSE) { days_in_month[2] = 29; return TRUE; } else { days_in_month[2] = 28; return FALSE; } } void calendar(int year, int daycode) { int month, day; for ( month = 1; month <= 12; month++ ) { printf("%s", months[month]); printf("\n\nSun Mon Tue Wed Thu Fri Sat\n" ); // Correct the position for the first date for ( day = 1; day <= 1 + daycode * 5; day++ ) { printf(" "); } // Print all the dates for one month for ( day = 1; day <= days_in_month[month]; day++ ) { printf("%2d", day ); // Is day before Sat? Else start next line Sun. if ( ( day + daycode ) % 7 > 0 ) printf(" " ); else printf("\n " ); } // Set position for next month daycode = ( daycode + days_in_month[month] ) % 7; } } int main(void) { int year, daycode, leapyear; year = inputyear(); daycode = determinedaycode(year); determineleapyear(year); calendar(year, daycode); printf("\n"); } This code generates a calendar of the inputed year in the terminal. my question is how can i convert this into a Objective-C syntax instead of this C syntax. im sure this is simple process but im quite of a novice to objective - c and i need it for a cocoa project. this code outputs the calendar as a continuously series of strings until the last month hits. soo instead of creating the calendar in the terminal how can i input the calendar a series of NSMatrixes depend on the inputed year. hope somone can help me with this thanks or every helps (you be in the credits of the finished program) :) (the calendar is just a small part of the program i making and it is one of the important parts!!)

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  • Project Euler (P14): recursion problems

    - by sean mcdaid
    Hi I'm doing the Collatz sequence problem in project Euler (problem 14). My code works with numbers below 100000 but with numbers bigger I get stack over-flow error. Is there a way I can re-factor the code to use tail recursion, or prevent the stack overflow. The code is below: import java.util.*; public class v4 { // use a HashMap to store computed number, and chain size static HashMap<Integer, Integer> hm = new HashMap<Integer, Integer>(); public static void main(String[] args) { hm.put(1, 1); final int CEILING_MAX=Integer.parseInt(args[0]); int len=1; int max_count=1; int max_seed=1; for(int i=2; i<CEILING_MAX; i++) { len = seqCount(i); if(len > max_count) { max_count = len; max_seed = i; } } System.out.println(max_seed+"\t"+max_count); } // find the size of the hailstone sequence for N public static int seqCount(int n) { if(hm.get(n) != null) { return hm.get(n); } if(n ==1) { return 1; } else { int length = 1 + seqCount(nextSeq(n)); hm.put(n, length); return length; } } // Find the next element in the sequence public static int nextSeq(int n) { if(n%2 == 0) { return n/2; } else { return n*3+1; } } }

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