Search Results

Search found 21054 results on 843 pages for 'the void'.

Page 2/843 | < Previous Page | 1 2 3 4 5 6 7 8 9 10 11 12  | Next Page >

  • How do I cast a void pointer to a struct in C?

    - by Rowhawn
    In a project I'm writing code for, I have a void pointer, "implementation", which is a member of a "Hash_map" struct, and points to an "Array_hash_map" struct. The concepts behind this project are not very realistic, but bear with me. The specifications of the project ask that I cast the void pointer "implementation" to an "Array_hash_map" before I can use it in any functions. My question, specifically is, what do I do in the functions to cast the void pointers to the desired struct? Is there one statement at the top of each function that casts them or do I make the cast every time I use "implementation"? Here are the typedefs the structs of a Hash_map and Array_hash_map as well as a couple functions making use of them. typedef struct { Key_compare_fn key_compare_fn; Key_delete_fn key_delete_fn; Data_compare_fn data_compare_fn; Data_delete_fn data_delete_fn; void *implementation; } Hash_map; typedef struct Array_hash_map{ struct Unit *array; int size; int capacity; } Array_hash_map; typedef struct Unit{ Key key; Data data; } Unit; functions: /* Sets the value parameter to the value associated with the key parameter in the Hash_map. */ int get(Hash_map *map, Key key, Data *value){ int i; if (map == NULL || value == NULL) return 0; for (i = 0; i < map->implementation->size; i++){ if (map->key_compare_fn(map->implementation->array[i].key, key) == 0){ *value = map->implementation->array[i].data; return 1; } } return 0; } /* Returns the number of values that can be stored in the Hash_map, since it is represented by an array. */ int current_capacity(Hash_map map){ return map.implementation->capacity; }

    Read the article

  • How to access a structure member in a function that get it as void* type?

    - by Ahmad
    I want to have a function that accepts different type of structures as argument. So, since I don't have a specific type, I have to use void*. Now question is: when I pass a structure to this function, how can I access a known member of this structure inside the function? Specifically, I know that all structures have str1 as a member and I want, for example, print it. Here is a sample code: struct { char* str1; float tt1; } var1 = {"This is me", 12}; struct { char* str1; int tt2; } var2 = {"This is you", 18}; void printStruct(void* str) { printf("\n the structure string is %s", ??); //can I put something in ?? to print the string? } main(....) { printStruct(&var1); printStruct(&var2); }

    Read the article

  • How can i use a variable created in a objective c Void function?

    - by James
    Im trying to get the lat and long values generated in a void function and use them within another function. Any help grateful. (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation { float latDeg = newLocation.coordinate.latitude; NSLog(@"Lat: %g", latDeg); float longDeg = newLocation.coordinate.longitude; NSLog(@"Lat: %g", longDeg); } I want to use the latDeg and longDeg variables.

    Read the article

  • Why not System.Void?

    - by Stewart
    I have no practical reason for knowing this answer, but I'm curious anyway... In C#, trying to use System.Void will produce a compilation error: error CS0673: System.Void cannot be used from C# -- use typeof(void) to get the void type object As I understood it, void is simply an alias of System.Void. So, I don't understand why 'System.Void' can't be used directly as you might with 'string' for 'System.String' for example. I would love to read an explanation for this! Incidentally, System.Void can be successfully used with the Mono compiler, instead of Microsoft's .Net, and there it appears equivalent to using the void keyword. This must therefore be a compiler-enforced restriction rather than a CLR restriction, right?

    Read the article

  • How to void checked exceptions in Java?

    - by deamon
    I consider checked exception for a design mistake in the Java language. They lead to leaky abstractions and a lot of clutter in the code. It seems that they force the programmer to handle exceptions early although they are in most cases better handled lately. So my question is how to avoid checked exception? My idea is to execute the actual code inside an exception translator using lambda expressions. Example: ExceptionConverter.convertToRuntimeException(() => { // do things that could throw checked exceptions here }); If for example a IOException occurs it gets rethrown as an exception with the same name but from a different class hierarchy (based on RuntimeException). This approach would effectivly remove the need to handle or declare checked exceptions. Exceptions could then be handled where and if it makes sense. Another solution would be to declare IOException throws Exception on each method. What do you think which solution is better? Do you know any better approach to avoid (suppress) checked exceptions in Java?

    Read the article

  • Function not returning value at all - not a void [migrated]

    - by user105439
    I have this function that is not returning a function value. I've added some random testers to try and debug but no luck. Thanks! #include <stdio.h> #include <math.h> #include <time.h> #define N 100 float error(int a, int b); int main(){ printf("START\n"); srand(time(NULL)); int a, b, j, m; float plot[N+1]; printf("Lower bound for x: "); scanf("%d", &a); printf("Upper bound for x: "); scanf("%d", &b); printf("okay\n"); for(j = 0; j < N; j++) plot[j] = 0; printf("okay1\n"); m = error(a,b); printf("%f\n",m); return 0; } float error(int a, int b){ float product = a*b; printf("%f\n",product); return product; } so the m = error(a,b) always gives 0 no matter what! Please help. I apologise for not cleaning this up...

    Read the article

  • Another void C# question

    - by Jim Jones
    Have a type in the header files I'm working with called VTVOID it is the type of a struct element and a number of parameters. In the header file defining types is the line #define VTVOID void I read in another discussion the void maps to System.Void however when I plug that into the C# code I get the error "System.Void cannot be used in C# -- use typeof(void) to get the void object." So what type do I plug in? Jim

    Read the article

  • IPHONE SDK, How to put Void function into my BOOL??? PLEASE!

    - by Harry
    I am using the IPhone's Accelerometer to make a object move. I want to be able to make this function work and not work depending on different states. I have my code for my Accelerometer function and i want to put it into a BOOL so i can call on it when i need it, but i am having problems. Can anyone Help me put this code into a BOOL named: -(BOOL) accelerometerWorks -(void) accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration{ valueX = acceleration.x*25.5; int newX = (int)(ball.center.x +valueX); if (newX > 320-BALL_RADIUS) newX = 320-BALL_RADIUS; if (newX < 0+BALL_RADIUS) newX = 0+BALL_RADIUS; int XA = (int)(balloonbit1.center.x +valueX); if (XA > 320-BALL_RADIUS) XA = 320-BALL_RADIUS; if (XA < 0+BALL_RADIUS) XA = 0+BALL_RADIUS; int XB = (int)(balloonbit2.center.x +valueX); if (XB > 320-BALL_RADIUS) XB = 320-BALL_RADIUS; if (XB < 0+BALL_RADIUS) XB = 0+BALL_RADIUS; int XE = (int)(balloonbit5.center.x +valueX); if (XE > 320-BALL_RADIUS) XE = 320-BALL_RADIUS; if (XE < 0+BALL_RADIUS) XE = 0+BALL_RADIUS; int XF = (int)(balloonbit6.center.x +valueX); if (XF > 320-BALL_RADIUS) XF = 320-BALL_RADIUS; if (XF < 0+BALL_RADIUS) XF = 0+BALL_RADIUS; int XH = (int)(balloonbit8.center.x +valueX); if (XH > 320-BALL_RADIUS) XH = 320-BALL_RADIUS; if (XH < 0+BALL_RADIUS) XH = 0+BALL_RADIUS; ball.center = CGPointMake (newX, 415); balloonbit1.center = CGPointMake (XA, 408); balloonbit2.center = CGPointMake (XB, 395); balloonbit5.center = CGPointMake (XE, 388); balloonbit6.center = CGPointMake (XF, 413); balloonbit8.center = CGPointMake (XH, 426); } Please help. i have been trying for ages with no success. Thanks. Harry.

    Read the article

  • Cast from Void* to TYPE* using C++ style cast: static_cast or reinterpret_cast

    - by David Relihan
    So if your converting from Void* to Type* or from Type* to Void* should you use: void func(void *p) { Params *params = static_cast<Params*>(p); } or void func(void *p) { Params *params = reinterpret_cast<Params*>(p); } To me static_cast seems the more correct but I've seen both used for the same purpose. Also, does the direction of the conversion matter. i.e. should I still use static_cast for: _beginthread(func,0,static_cast<void*>(params) I have read the other questions on C++ style casting but I'm still not sure what the correct way is for this scenario (I think it is static_cast)

    Read the article

  • Initialize void pointer to point to an array

    - by idealistikz
    Suppose I have the following: typedef struct { int itemSize; int count; void *list; } Mystruct; Mystruct *InitStruct(int itemSize, int count) { Mystruct *my = malloc(sizeof(Mystruct)); my->itemSize = itemSize; my->count = count; //What is the best way to initialize list? For example: //my->list = malloc(count * sizeof(void *)); OR //my->list = malloc(count * sizeof(itemSize)); } //The following should return a pointer to the element stored at a given index void *Retrieve(const MyStruct *my, int index) { void *item; //What is the best way to return a pointer to the item at the given index from //my->list? } Mystruct is similar to an array and void *list is supposed to store the elements or pointers to the elements. Mystruct *InitStruct is a function that initializes a Mystruct pointer and void *Retrieve is a function that returns a pointer to the element stored at a given index. First, how should I initialize void* list? Should it hold the actual elements or be an array of pointers pointing to the elements? Second, using the void *Retrieve function, how do I return a pointer to the element stored at a given index in my-list?

    Read the article

  • How to convert a void pointer to array of classes

    - by user99545
    I am trying to convert a void pointer to an array of classes in a callback function that only supports a void pointer as a means of passing paramaters to the callback. class person { std::string name, age; }; void callback (void *val) { for (int i = 0; i < 9; i++) { std::cout << (person [])val[i].name; } } int main() { person p[10]; callback((void*)p); } My goal is to be able to pass an array of the class person to the callback which then prints out the data such as their name and age. However, the compile does not like what I am doing and complains that error: request for member 'name' in 'val', which is of non-class type 'void*' How can I go about doing this?

    Read the article

  • pass objective c object and primitive type into a void *

    - by user674669
    I want to pass 2 variables: UIImage * img int i into another method that only takes a (void *) I tried making a C struct containing both img and i struct MyStruct { UIImage *img; int i; } but xcode gives me an error saying "ARC forbids Objective-C objects in structs or unions" The next thing I tried is to write an objective-c class MyStruct2 containing img and i, alloc-initing an instance of it and typecasting it as (__bridge void*) before passing it to the method. Seems little involved for my use case. Seems like there should be a better way. What's the simplest way to achieve this? Thank you. Edit based on comments: I have to use void * as it is required by the UIView API. I created a selector as mentioned by UIVIew API + (void)setAnimationDidStopSelector:(SEL)selector Please see documentation for setAnimationDidStopSelector at http://developer.apple.com/library/ios/#documentation/uikit/reference/UIView_Class/UIView/UIView.html . It says ... The selector should be of the form: - (void)animationDidStop:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context I want to pass both img and i into the (void *)context argument.

    Read the article

  • error: 'void Base::output()' is protected within this context

    - by Bill
    I'm confused about the errors generated by the following code. In Derived::doStuff, I can access Base::output directly by calling it. Why can't I create a pointer to output() in the same context that I can call output()? (I thought protected / private governed whether you could use a name in a specific context, but apparently that is incomplete?) Is my fix of writing callback(this, &Derived::output); instead of callback(this, Base::output) the correct solution? #include <iostream> using std::cout; using std::endl; template <typename T, typename U> void callback(T obj, U func) { ((obj)->*(func))(); } class Base { protected: void output() { cout << "Base::output" << endl; } }; class Derived : public Base { public: void doStuff() { // call it directly: output(); Base::output(); // create a pointer to it: // void (Base::*basePointer)() = &Base::output; // error: 'void Base::output()' is protected within this context void (Derived::*derivedPointer)() = &Derived::output; // call a function passing the pointer: // callback(this, &Base::output); // error: 'void Base::output()' is protected within this context callback(this, &Derived::output); } }; int main() { Derived d; d.doStuff(); }

    Read the article

  • static_cast from Derived* to void* to Base*

    - by Roberto
    I would like to cast a pointer to a member of a derived class to void* and from there to a pointer of the base class, like in the example below: #include <iostream> class Base { public: void function1(){std::cout<<"1"<<std::endl;} virtual void function2()=0; }; class Derived : public Base { public: virtual void function2(){std::cout<<"2"<<std::endl;} }; int main() { Derived d; void ptr* = static_cast<void*>(&d); Base* baseptr=static_cast<Base*>(ptr); baseptr->function1(); baseptr->function2(); } This compiles and gives the desired result (prints 1 and 2 respectively), but is it guaranteed to work? The description of static_cast I found here: http://en.cppreference.com/w/cpp/language/static_cast only mentions conversion to void* and back to a pointer to the same class (point 10).

    Read the article

  • generic programming in C with void pointer.

    - by Nyan
    Hi everyone, even though it is possible to write generic code in C using void pointer(generic pointer), I find that it is quite difficult to debug the code since void pointer can take any pointer type without warning from compiler. (e.g function foo() take void pointer which is supposed to be pointer to struct, but compiler won't complain if char array is passed.) What kind of approach/strategy do you all use when using void pointer in C?

    Read the article

  • Mock a void method which change the input value

    - by Kar
    Hi, How could I mock a void method with parameters and change the value parameters? My void method looks like this: public interface IFoo { void GetValue(int x, object y) // takes x and do something then access another class to get the value of y } I prepared a delegate class: private delegate void GetValueDelegate(int x, object y); private void GetValue(int x, object y) { // process x // prepare a new object obj if (y == null) y = new Object(); if (//some checks) y = obj; } I wrote something like this: Expect.Call(delegate {x.GetValue(5, null);}).Do (new GetValueDelegate(GetValue)).IgnoreArguments().Repeat.Any(); But seems like it's not working. Any clue on what could be wrong?

    Read the article

  • How to Smooth the drawing Stroke?

    - by user1852420
    I am creating drawing.. i can undo, and put colors on it. but when i draw using my fingers the stroke is not that smooth and has edge lines,, here my codes. on which I can Paint on a view, Undo, change color, and the opacity. stroke.h #import <UIKit/UIKit.h> @interface stroke : UIView{ NSMutableArray *strokeArray; UIColor *strokeColor; int strokeSize; float strokeAlpha; int strokeAlpha2; IBOutlet UISlider *slides; float red; float green; float blue; CGPoint mid1; CGPoint mid2; CGPoint endingPoint,previousPoint1,previousPoint2; CGPoint currentTouch; } @property (nonatomic, retain) UIColor *strokeColor; @property (nonatomic) int strokeSize; @property (nonatomic, retain) NSMutableArray *strokeArray; - (IBAction)changeAlphaValue; -(void)loadSLider; -(void)blueColor; -(void)darkvioletColor; -(void)violetColor; -(void)pinkColor; -(void)darkbrownColor; -(void)redColor; -(void)magentaRedColor; -(void)lightBrownColor; -(void)lightOrangeColor; -(void)OrangeColor; -(void)YellowColor; -(void)greenColor; -(void)lightYellowColor; -(void)darkGreenColor; -(void)TurquioseColor; -(void)PaleTurquioseColor; -(void)skyBlueColor; -(void)whiteColor; -(void)DirtyWhiteColor; -(void)SilverColor; -(void)LightGrayColor; -(void)GrayColor; -(void)LightBlackColor; -(void)BlackColor; @end stroke.m #import "stroke.h" @implementation stroke @synthesize strokeColor; @synthesize strokeSize; @synthesize strokeArray; - (void) awakeFromNib{ self.strokeArray = [[NSMutableArray alloc] init]; self.strokeColor = [UIColor colorWithRed:0 green:0 blue:232 alpha:1]; self.strokeSize = 3; } - (void)drawRect:(CGRect)rect{ NSMutableArray *stroke; for (stroke in strokeArray) { CGContextRef contextRef = UIGraphicsGetCurrentContext(); CGContextSetLineWidth(contextRef, [[stroke objectAtIndex:1] intValue]); CGFloat *color = CGColorGetComponents([[stroke objectAtIndex:2] CGColor]); CGContextSetRGBStrokeColor(contextRef, color[0], color[1], color[2], color[3]); CGContextBeginPath(contextRef); CGPoint points[[stroke count]]; for (NSUInteger i = 3; i < [stroke count]; i++) { points[i-3] = [[stroke objectAtIndex:i] CGPointValue]; } CGContextAddLines(contextRef, points, [stroke count]-3); CGContextStrokePath(contextRef); } } -(void)loadSLider{ } - (IBAction)changeAlphaValue{ strokeAlpha2 =((int)slides.value); } -(void)blueColor{ red = 0/255.0; green = 0/255.0; blue = 255/255.0; } -(void)darkvioletColor{ red = 75/255.0; green = 0/255.0; blue = 130/255.0; } -(void)violetColor{ red = 128/255.0; green = 0/255.0; blue = 128/255.0; } -(void)pinkColor{ red = 255/255.0; green = 0/255.0; blue = 255/255.0; } -(void)darkbrownColor{ red = 0.200; green = 0.0; blue = 0.0; } -(void)redColor{ red = 255/255.0; green = 0/255.0; blue = 0/255.0; } -(void)magentaRedColor{ red = 0.350; green = 0.0; blue = 0.0; } -(void)lightBrownColor{ red = 0.480; green = 0.0; blue = 0.0; } -(void)lightOrangeColor{ red = 0.600; green = 0.200; blue = 0.0; } -(void)OrangeColor{ red = 1.0; green = 0.300; blue = 0.0; } -(void)YellowColor{ red = 0.950; green = 0.450; blue = 0.0; } -(void)greenColor{ red = 0.0; green = 1.0; blue = 0.0; } -(void)lightYellowColor{ red = 1.0; green = 1.0; blue = 0.0; } -(void)darkGreenColor{ red = 0.0; green = 0.500; blue = 0.0; } -(void)TurquioseColor{ red = 0.0; green = 0.700; blue = 0.200; } -(void)PaleTurquioseColor{ red = 0.0; green = 0.700; blue = 0.600; } -(void)skyBlueColor{ red = 0.0; green = 0.400; blue = 0.800; } -(void)whiteColor{ red = 1.0; green = 1.0; blue = 1.0; } -(void)DirtyWhiteColor{ red = 0.800; green = 0.800; blue = 0.800; } -(void)SilverColor{ red = 0.600; green = 0.600; blue = 0.600; } -(void)LightGrayColor{ red = 0.500; green = 0.500; blue = 0.500; } -(void)GrayColor{ red = 0.300; green = 0.300; blue = 0.300; } -(void)LightBlackColor{ red = 0.150; green = 0.150; blue = 0.150; } -(void)BlackColor{ red = 0.0; green = 0.0; blue = 0.0; } - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch; NSEnumerator *counter = [touches objectEnumerator]; while ((touch = (UITouch *)[counter nextObject])) { switch (strokeAlpha2) { case 1: strokeAlpha = .1; break; case 2: strokeAlpha = .2; break; case 3: strokeAlpha = .3; break; case 4: strokeAlpha = .4; break; case 5: strokeAlpha = .5; break; case 6: strokeAlpha = .6; break; case 7: strokeAlpha = .7; break; case 8: strokeAlpha = .8; break; case 9: strokeAlpha = .9; break; case 10: strokeAlpha = 1; break; default: strokeAlpha = 1; break; } self.strokeColor = [UIColor colorWithRed:red green:green blue:blue alpha:strokeAlpha]; NSValue *touchPos = [NSValue valueWithCGPoint:[touch locationInView:self]]; UIColor *color = [UIColor colorWithCGColor:strokeColor.CGColor]; NSNumber *size = [NSNumber numberWithInt:strokeSize]; NSMutableArray *stroke = [NSMutableArray arrayWithObjects: touch, size, color, touchPos, nil]; [strokeArray addObject:stroke]; } } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch; NSEnumerator *counter = [touches objectEnumerator]; while ((touch = (UITouch *)[counter nextObject])) { NSMutableArray *stroke; for (stroke in strokeArray) { if ([stroke objectAtIndex:0] == touch) { [stroke addObject:[NSValue valueWithCGPoint:[touch locationInView:self]]]; } [self setNeedsDisplay]; } } } @end

    Read the article

  • Converting C# void* to byte[]

    - by Yurik
    In C#, I need to write T[] to a stream, ideally without any additional buffers. I have a dynamic code that converts T[] (where T is a no-objects struct) to a void* and fixes it in memory, and that works great. When the stream was a file, I could use native Windows API to pass the void * directly, but now I need to write to a generic Stream object that takes byte[]. Can anyone suggest a hack way to create a dummy array object which does not actually have any heap allocations, but rather points to an already existing (and fixed) heap location. This is the pseudo-code that I need: void Write(Stream stream, T[] buffer) { fixed( void* ptr = &buffer ) // done with dynamic code generation { int typeSize = sizeof(T); // done as well byte[] dummy = (byte[]) ptr; // <-- how do I create this fake array? stream.Write( dummy, 0, buffer.Length*typeSize ); } }

    Read the article

  • How to gain Access to member variables of a class using void pointer but Not Object

    - by mahesh
    Hi, I am trying to access member variables of a class without using object. please let me know how to go about. class TestMem { int a; int b; public: TestMem(){} void TestMem1() { a = 10; b = 20; } }; void (TestMem::*pMem)(); int main(int argc, char* argv[]) { TestMem o1; pMem = &(TestMem::TestMem1); void *p = (void*)&pMem; // How to access a & b member variables using variable p getch(); return 0; }

    Read the article

  • Returning a variable in a public void...

    - by James Rattray
    Hello, I'm abit new to programming Android App's, however I have come across a problem, I can't find a way to make global variables -unlike other coding like php or VB.NET, are global variables possible? If not can someone find a way (and if possible implement the way into the code I will provide below) to get a value from the variable 'songtoplay' so I can use in another Public Void... Here is the code: final Spinner hubSpinner = (Spinner) findViewById(R.id.myspinner); ArrayAdapter adapter = ArrayAdapter.createFromResource( this, R.array.colours, android.R.layout.simple_spinner_item); adapter .setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); hubSpinner.setAdapter(adapter); // hubSpinner.setOnItemSelectedListener(new OnItemSelectedListener() { public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) { //code Object ttestt = hubSpinner.getSelectedItem(); final String test2 = ttestt.toString(); Toast message1 = Toast.makeText(Textbox.this, test2, Toast.LENGTH_LONG); message1.show(); String songtoplay = test2; // Need songtoplay to be available in another 'Public Void' } public void onNothingSelected(AdapterView<?> parentView) { //Code } }); Basically, it gets the value from the Spinner 'hubSpinner' and displays it in a Toast. I then want it to return a value for string variable 'songtoplay' -or find a way to make it global or useable in another Public Void, (Which is will a button, -loading the song to be played) Please help me, Thanks alot. James

    Read the article

  • Passing Derived Class Instances as void* to Generic Callbacks in C++

    - by Matthew Iselin
    This is a bit of an involved problem, so I'll do the best I can to explain what's going on. If I miss something, please tell me so I can clarify. We have a callback system where on one side a module or application provides a "Service" and clients can perform actions with this Service (A very rudimentary IPC, basically). For future reference let's say we have some definitions like so: typedef int (*callback)(void*); // This is NOT in our code, but makes explaining easier. installCallback(string serviceName, callback cb); // Really handled by a proper management system sendMessage(string serviceName, void* arg); // arg = value to pass to callback This works fine for basic types such as structs or builtins. We have an MI structure a bit like this: Device <- Disk <- MyDiskProvider class Disk : public virtual Device class MyDiskProvider : public Disk The provider may be anything from a hardware driver to a bit of glue that handles disk images. The point is that classes inherit Disk. We have a "service" which is to be notified of all new Disks in the system, and this is where things unravel: void diskHandler(void *p) { Disk *pDisk = reinterpret_cast<Disk*>(p); // Uh oh! // Remainder is not important } SomeDiskProvider::initialise() { // Probe hardware, whatever... // Tell the disk system we're here! sendMessage("disk-handler", reinterpret_cast<void*>(this)); // Uh oh! } The problem is, SomeDiskProvider inherits Disk, but the callback handler can't receive that type (as the callback function pointer must be generic). Could RTTI and templates help here? Any suggestions would be greatly appreciated.

    Read the article

< Previous Page | 1 2 3 4 5 6 7 8 9 10 11 12  | Next Page >