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  • Could I ever want to access the address zero?

    - by Joel
    The constant 0 is used as the null pointer in C and C++. But as in http://stackoverflow.com/questions/2389251/pointer-to-a-specific-fixed-address there seems to be some possible use of assigning fixed addresses. Is there ever any conceivable need, in any system, for whatever low level task, for accessing the address 0? If there is, how is that solved with 0 being the null pointer and all? If not, what makes it certain that there is not such a need?

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  • Find out when all processes in (void) is done?

    - by Emil
    Hey. I need to know how you can find out when all processes (loaded) from a - (void) are done, if it's possible. Why? I'm loading in data for a UITableView, and I need to know when a Loading... view can be replaced with the UITableView, and when I can start creating the cells. This is my code: - (void) reloadData { NSAutoreleasePool *releasePool = [[NSAutoreleasePool alloc] init]; NSLog(@"Reloading data."); NSURL *urlPosts = [NSURL URLWithString:[NSString stringWithFormat:@"%@", URL]]; NSError *lookupError = nil; NSString *data = [[NSString alloc] initWithContentsOfURL:urlPosts encoding:NSUTF8StringEncoding error:&lookupError]; postsData = [data componentsSeparatedByString:@"~"]; [data release], data = nil; urlPosts = nil; self.numberOfPosts = [[postsData objectAtIndex:0] intValue]; self.postsArrayID = [[postsData objectAtIndex:1] componentsSeparatedByString:@"#"]; self.postsArrayDate = [[postsData objectAtIndex:2] componentsSeparatedByString:@"#"]; self.postsArrayTitle = [[postsData objectAtIndex:3] componentsSeparatedByString:@"#"]; self.postsArrayComments = [[postsData objectAtIndex:4] componentsSeparatedByString:@"#"]; self.postsArrayImgSrc = [[postsData objectAtIndex:5] componentsSeparatedByString:@"#"]; NSMutableArray *writeToPlist = [NSMutableArray array]; NSMutableArray *writeToNoImagePlist = [NSMutableArray array]; NSMutableArray *imagesStored = [NSMutableArray arrayWithContentsOfFile:[rootPath stringByAppendingPathComponent:@"imagesStored.plist"]]; int loop = 0; for (NSString *postID in postsArrayID) { if ([imagesStored containsObject:[NSString stringWithFormat:@"%@.png", postID]]){ NSLog(@"Allready stored, jump to next. ID: %@", postID); continue; } NSLog(@"%@.png", postID); NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:[postsArrayImgSrc objectAtIndex:loop]]]; // If image contains anything, set cellImage to image. If image is empty, try one more time or use noImage.png, set in IB if (imageData == nil){ NSLog(@"imageData is empty before trying .jpeg"); // If image == nil, try to replace .jpg with .jpeg, and if that worked, set cellImage to that image. If that is also nil, use noImage.png, set in IB. imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:[[postsArrayImgSrc objectAtIndex:loop] stringByReplacingOccurrencesOfString:@".jpg" withString:@".jpeg"]]]; } if (imageData != nil){ NSLog(@"imageData is NOT empty when creating file"); [fileManager createFileAtPath:[rootPath stringByAppendingPathComponent:[NSString stringWithFormat:@"images/%@.png", postID]] contents:imageData attributes:nil]; [writeToPlist addObject:[NSString stringWithFormat:@"%@.png", postID]]; } else { [writeToNoImagePlist addObject:[NSString stringWithFormat:@"%@", postID]]; } imageData = nil; loop++; NSLog(@"imagePlist: %@\nnoImagePlist: %@", writeToPlist, writeToNoImagePlist); } NSMutableArray *writeToAllPlist = [NSMutableArray arrayWithArray:writeToPlist]; [writeToPlist addObjectsFromArray:[NSArray arrayWithContentsOfFile:nowPlist]]; [writeToAllPlist addObjectsFromArray:[NSArray arrayWithContentsOfFile:[rootPath stringByAppendingPathComponent:@"imagesStored.plist"]]]; [writeToNoImagePlist addObjectsFromArray:[NSArray arrayWithContentsOfFile:[rootPath stringByAppendingPathComponent:@"noImage.plist"]]]; [writeToPlist writeToFile:nowPlist atomically:YES]; [writeToAllPlist writeToFile:[rootPath stringByAppendingPathComponent:@"imagesStored.plist"] atomically:YES]; [writeToNoImagePlist writeToFile:[rootPath stringByAppendingPathComponent:@"noImage.plist"] atomically:YES]; [releasePool release]; }

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  • Released object crashes app

    - by John Smith
    I am using objective-C++ (+Boost) for iPhone development. I am in a rather tight loop and need to allocate and release a certain object. The code is something like this. for (int i=0;i<100;i++) { opt = [[FObj alloc] init]; //do stuff with opt [opt release]; } The FObj object is something like @interface FObj MyCPPObj * cppobj; @end In the implementation of FObj there is a dealloc method: -(void) dealloc { delete cppobj; //previously allocated with 'new' [super dealloc]; } I am afraid that if i don't release then the 'MyCPPObj's will just pile up. But releasing makes the app crash after the first loop. What am I doing wrong? Or perhaps should I make cppobj and boost::shared_ptr? (do boost shared pointers automatically release their objects when an objective-C++ object is deleted?)

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  • NSString potential leak

    - by VansFannel
    Hello. When I build and analyze my project on XCode, I obtain a 'warning' on the following line: NSString *contactEmail = (NSString *)ABMultiValueCopyValueAtIndex(emailInfo, 0); The message is: Potential leak on object allocated on line ... and stored into contactEmail. Is there any error on that line? UPDATE I get the same 'warning' with this line of code: ABMultiValueRef emailInfo = ABRecordCopyValue(person, kABPersonEmailProperty); But here, I can't do this: [emailInfo release]; I'm developing for iPhone.

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  • allocator with no template

    - by Merni
    Every stl container take an allocator as a second object, template < class T, class Allocator = allocator<T> > class vector; If you write your own class It is possible to use your own allocator. But is it possible to write your own allocator without using templates? For example, writing this function is not easy if you are not allowed to use templates pointer allocate(size_type n, const_pointer = 0) { void* p = std::malloc(n * sizeof(T)); if (!p) throw std::bad_alloc(); return static_cast<pointer>(p); } Because how could you know the size of T?

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  • Implementing Barrier system solution in C or C++

    - by hardikpatel172
    Actually I have been assigned to implement Barrier system solution in either C or C++ programming language... But I have zero knowledge about it ... I know the problem as well as solution theoritically.. But I have no idea how to implement it.... How can it be possible in C++ to stop or run or wait any process.... Plz yaar... Anyone help me... It's urgent...

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  • NSMutableArray accessing issue.

    - by Danegraphics
    I've searched and have no answer. I've created an NSMutableArray and am getting an EXC_BAD_ACCESS error in one place of access. Here. This is declaring in the .h file: NSMutableArray *buttons; ... @property (nonatomic, retain)NSMutableArray *buttons; And this is the synthesizing and implimenting: @synthesize buttons; ... - (id)init { self = [super init]; if(self != nil) { buttons = [[NSMutableArray alloc] init]; } return self; } ... -(void)addButtonWithImage:(Image*)image { Image *button = image; [buttons addObject:button]; [button release]; } ... -(void)replaceButtonAt:(int)num with:(Image*)image { Image *button = image; [buttons replaceObjectAtIndex:num withObject:button]; <<===EXC_BAD_ACCESS [button release]; } But when I use this: -(void)renderButton:(int)num atPoint:(CGPoint)point center:(BOOL)center{ Image *button = [buttons objectAtIndex:num]; [button renderAtPoint:point centerOfImage:center]; } It works

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  • Big time Leaking in Objective-C Category

    - by Daniel Amitay
    I created a custom NSString Category which lets me find all strings between two other strings. I'm now running into the problem of finding that there are a lot of kBs leaking from my script. Please see code below: #import "MyStringBetween.h" @implementation NSString (MyStringBetween) -(NSArray *)mystringBetween:(NSString *)aString and:(NSString *)bString; { NSAutoreleasePool *autoreleasepool = [[NSAutoreleasePool alloc] init]; NSArray *firstlist = [self componentsSeparatedByString:bString]; NSMutableArray *finalArray = [[NSMutableArray alloc] init]; for (int y = 0; y < firstlist.count - 1 ; y++) { NSString *firstObject = [firstlist objectAtIndex:y]; NSMutableArray *secondlist = [firstObject componentsSeparatedByString:aString]; if(secondlist.count > 1){ [finalArray addObject:[secondlist objectAtIndex:secondlist.count - 1]]; } } [autoreleasepool release]; return finalArray; } @end I admit that I'm not super good at releasing objects, but I had believed that the NSAutoreleasePool handled things for me. The line that is leaking: NSMutableArray *secondlist = [firstObject componentsSeparatedByString:aString]; Manually releasing secondlist raises an exception. Thanks in advance!

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  • Can I use MFC objects in STL containers?

    - by Jesse Stimpson
    The following code doesn't compile for me in MSVC2005: std::vector<CMenu> vec(10); CMenu is an MFC menu object (such as a context menu). Through some testing I learned that CMenu does not have a public copy constructor. To do what I wanted to do, I needed to use a dynamic array. CMenu* menus = new CMenu[10]; // ... delete [] menus; Of course, now I've lost all the benefits of using an STL container. Do I have any other options?

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  • Developing Bots__Where can I start?

    - by user947659
    i have a pet programming goal: to develop a bot for a game. Now, this won't be anything malicious, and I just want to do this to further my knowledge in programming. Can anyone help me out by pointing to where i can start learning how to develop a bot? the type of bots i want to make are video game bots (online multiplayer, first person shooters, and offline games(like solitaire and such)). Thanks!

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  • What to throw in a C++ class wrapping a C library ?

    - by ereOn
    I have to create a set of wrapping C++ classes around an existing C library. For many objects of the C library, the construction is done by calling something like britney_spears* create_britney_spears() and the opposite function void free_britney_spears(britney_spears* brit). If the allocation of a britney_spears fails, create_britney_spears() returns NULL. This is, as far as I know, a very common pattern. Now I want to wrap this inside a C++ class. //britney_spears.hpp class BritneySpears { public: BritneySpears(); private: boost::shared_ptr<britney_spears> m_britney_spears; }; And here is the implementation: // britney_spears.cpp BritneySpears::BritneySpears() : m_britney_spears(create_britney_spears(), free_britney_spears) { if (!m_britney_spears) { // Here I should throw something to abort the construction, but what ??! } } So the question is in the code sample: What should I throw to abort the constructor ? I know I can throw almost anything, but I want to know what is usually done. I have no other information about why the allocation failed. Should I create my own exception class ? Is there a std exception for such cases ? Many thanks.

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  • Can I catch bad pointer errors in C++?

    - by Simon
    Hi there, I was wondering if there is a possibility to catch errors like this in C++: object* p = new object; delete p; delete p; //this would cause an error, can I catch this? Can I check if the pointer is valid? Can I catch some exception? I know I could set the pointer p to NULL after the first object deletion. But just imagine you wouldn't do that. I am using VC++ with Visual Studio 2008/2010. Thank you

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  • What does CPU Time consist of? [closed]

    - by Sid
    What does CPU time exactly consist of? For instance, is the time taken to access a page from the RAM (at which point, the CPU is most likely idling) part of the CPU time? I'm not talking about fetching the page from the disk here, just fetching it from the RAM. Thanks

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  • Release resources in .Net C#

    - by zaidwaqi
    Hi, I'm new to C# and .NET, ,and have been reading around about it. I need to know why and when do I need to release resources? Doesn't the garbage collector take care of everything? When do I need to implement IDisposable, and how is it different from destructor in C++? Also, if my program is rather small i.e. a screensaver, do I need to care about releasing resources? Thanks.

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  • Will this be garbage collected in JVM?

    - by stjowa
    I am running the following code every two minutes via a Timer: object = new Object(this); Potentially, this is a lot of objects being created and a lot of objects being overwritten. Do the overwritten objects get garbage collected, even with a reference to itself being used in the newly created object? I am using JDK 1.6.0_13. Thanks for the help.

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  • Iphone release problem

    - by xger86x
    Hi, i have the following code in a .h @property (nonatomic, copy) NSString *username; Then, username is assigned in this way when the user enter text in a TextField: self.username = textField.text; And then, in dealloc method i call release: NSLog(@"%d",[username retainCount]); [username release]; NSLog(@"%d",[username retainCount]); But in the console it prints: 2011-01-11 23:09:52.468 IApp[2527:307] 1 2011-01-11 23:09:52.480 IApp[2527:307] 1 What is the problem? Thanks

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  • Should repeated use of the camera crash an app?

    - by Sam
    I have an app that builds a slideshow from user images. They can grab from their library or take a picture. I have found that repeated use of grabbing an image from the library is fine. But repeated use of taking a picture causes erratic behavior. I have been getting crashes but mostly what happens seems to be a reloading of the view after "didFinishPickingMediaWithInfo", which messes things up. I have no leaks and it seems to be releasing properly after each picture is taken. I am resizing the image and saving it in a data base. Is anyone else running into this situation? Was the camera not designed to be called this often?

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  • Using std::bad_alloc for C pointers

    - by otibom
    I'm using a library written in C in a C++ project. I'd like to use C++ exceptions to handle C errors. In particular, it would be nice to have an exception thrown if an allocation fails. I can do this in constructors of classes which hold C-style pointers to C structs : if (c_object == NULL) throw std::bad_alloc(); But if the class is responsible for several C objects they are no ways of free-ing all already allocated pointers since the destructor isn't called. I have a feeling I could use smart-pointers, but I don't have much experience with them. What's more, I have to have access to the original C pointers to use the C api properly. Is there an elegant solution to this ?

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  • Static variables within functions in C++ - allocated even if function doesn't run?

    - by John C
    I've been reading up on C++ on the Internet, and here's one thing that I haven't been quite able to find an answer to. I know that static variables used within functions are akin to globals, and that subsequent invocations of that function will have the static variable retain its value between calls. However, if the function is never claled, does the static variable get allocated? Thanks

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  • Linking to a Large address aware DLL.

    - by Canopus
    Suppose I have a DLL which is built with LARGEADDRESSAWARE linker flag set. Now I have an application dynamically linking to this DLL. Does this make my application LARGEADDRESSAWARE? If not then, does it make sense to have this flag set for any DLL?

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  • How much RAM used by Python dict or list?

    - by Who8MyLunch
    My problem: I am writing a simple Python tool to help me visualize my data as a function of many parameters. Each change in parameters involves a non-trivial amount of time, so I would like to cache each step's resulting imagery and supporting data in a dictionary. But then I worry that this dictionary could grow too large over time. Most of my data is in the form of Numpy arrays. My question: How would one go about computing the total number of bytes used by a Python dictionary. The dictionary itself may contain lists and other dictionaries, each of which contain data stored in Numpy arrays. Ideas?

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  • How costly performance-wise are these actions in iPhone objective-C?

    - by Alex Gosselin
    This is really a few questions in one, I'm wondering what the performance cost is for these things, as I haven't really been following a best practice of any sort for these. The answers may also be useful to other readers, if somebody knows these. (1) If I need the core data managed object context, is it bad to use #import "myAppDelegate.h" //farther down in the code: NSManagedObjectContext *context = [(myAppDelegate.h*)[[UIApplication sharedApplication] delegate] managedObjectContext]; as opposed to leaving the warning you get if you don't cast the delegate? (2) What is the cheapest way to hard-code a string? I have been using return @"myString"; on occasion in some functions where I need to pass it to a variety of places, is it better to do it this way: static NSString *str = @"myString"; return str; (3) How costly is it to subclass an object i wrote vs. making a new one, in general? (4) When I am using core data and navigating through a hierarchy of some sort, is it necessary to turn things back into faults somehow after I read some info from them? or is this done automatically? Thanks for any help.

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