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  • Use of malloc() and free() in C++

    - by Matt H
    Is there any reason to use malloc and free in C++ over their more modern counterparts? Occasionally I see this, and I can't see why some people do it. Are there any advantages/disadvantage, or is there no real difference, except that it's just better to use C++ constructs in C++?

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  • Assigning unsigned char* buffer to a string

    - by CPPChase
    This question might be asked before but I couldn't find exactly what I need. My problem is, I have a buffer loaded by data downloaded from a webservice. The buffer is in unsigned char* form in which there is no '\0' at the end. Then I have a poco xml parser needs a string. I tried assigning it to string but now I realized it would cause problem such as leaking. here is the code: DOMParser::DOMParser(unsigned char* consatData, int consatDataSize, unsigned char* lagData, int lagDataSize) { Poco::XML::DOMParser parser; std::string consat; consat.assign((const char*) consatData, consatDataSize); pDoc = parser.parseString(consat); ParseConsat(); } Poco xml parser does have a ParseMemory which need a const char* and size of data but for some reason it just gives me segmentation fault. So I think it's safer to turn it to string. Thanks in advance.

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  • Does allocation speed depend on the garbage collector being used?

    - by jkff
    My app is allocating a ton of objects (1mln per second; most objects are byte arrays of size ~80-100 and strings of the same size) and I think it might be the source of its poor performance. The app's working set is only tens of megabytes. Profiling the app shows that GC time is negligibly small. However, I suspect that perhaps the allocation procedure depends on which GC is being used, and some settings might make allocation faster or perhaps make a positive influence on cache hit rate, etc. Is that so? Or is allocation performance independent on GC settings under the assumption that garbage collection itself takes little time?

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  • Iterate attributes and IBOutlets of a UIViewController

    - by Espuz
    I've a generic UIViewController on my app. All the UIViewController on the app inherits from this generic one. I'm trying to automate the deallocation and releasing of attributes and IBOutlets as properties. I'm doing the first (attributes) on dealloc method and the second (IBOutlets as properties) on viewDidUnload. - (void) dealloc { [_att1 release]; _att1 = nil; [_att2 release]; _att2 = nil; // ... } - (void) viewDidUnload { self.att1 = nil; // att1 is an IBOutlet self.att2 = nil; // att2 is an IBOutlet // ... } Is there any way to iterate all my attributes and IBOutlets to simplify this operations? I want to avoid do it for each outlet and attribute and delegate it to the generic UIViewController. Thanks.

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  • Phonegap: Will my mobile app 'feel' faster or slower once ported to phonegap?

    - by user15872
    So I'm designing everything in mobile Safari and I know that phonegap is essentially a stripped webview but... Question: Will my application will run better in phonegap? (revised below) a)I imagine my navigation and core app will load faster as the scripts and images are on the hard drive. Is this True? b)I assume since they've been working on it for 2 years now that they may have made some optimizations to make it quicker than just an average safari window. Is this true? (Assuming both html5/js/css code bases are pretty much the same and app is running on iOS.) Update: Sorry, I meant to compare apples to slightly different apples. Question 1 revised: Will my app see any performance benefits running with in a phonegap environment vs standard mobile safari? (compare mobile - to mobile) 1b) In what ways, other than loading time has phonegap optimized performance over standard mobile safari? Follow ups: 1) Are there any pitfalls, other than large libraries, that may cause phonegap to suffer a serious performance hit vs stand mobile safari? 2) Can I mix native and webview rendering? (i.e the top half of my app is rendered in with html/css/js and the bottom half native)

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  • How to release a string created inside a method in iphone?

    - by Warrior
    I have declared a local string inside the method.I am releasing the string inside the same method.I found my code crashing if release that object.If i dont release the string,code runs successfully.I have called that method in viewdidappear so that method is called while pushing and poping.Nothing gets printed in the console. Here is my code -(void)appendString{ NSString *locStr = [[NSString alloc] initWithString:@""]; for (int i=0;i<[result count]; i++) { locStr=[locStr stringByAppendingFormat:@"%@",[result objectAtIndex:i]]; } [str setString:locStr]; [locStr release]; } I am calling the "appendString" method from "viewDidAppear"."str" is a NSMutable string declared in .h class.How should i release the "locStr" .Please help me out

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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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  • 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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  • 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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  • 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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  • 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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  • C#. Struct design. Why 16 byte is recommended size?

    - by maxima120
    I read Cwalina book (recommendations on development and design of .NET apps). He says that good designed struct has to be less than 16 bytes in size (for performance purpose). My questions is - why exactly is this? And (more important) can I have larger struct with same efficiency if I run my .NET 3.5 (soon to be .NET 4.0) 64-bit application on i7 under Win7 x64 (is this limitation CPU / OS based)? Just to stress again - I need as efficient struct as it is possible. I try to keep it in stack all the time, the application is heavily multi-threaded and runs on sub-millisecond intervals, the current size of the struct is 64 byte.

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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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  • What collection object is appropriate for fixed ordering of values?

    - by makerofthings7
    Scenario: I am tracking several performance counters and have a CounterDescription[] correlate to DataSnapshot[]... where CounterDescription[n] describes the data loaded within DataSnapshot[n]. I want to expose an easy to use API within C# that will allow for the easy and efficient expansion of the arrays. For example CounterDescription[0] = Humidity; DataSnapshot[0] = .9; CounterDescription[1] = Temp; DataSnapshot[1] = 63; My upload object is defined like this: Note how my intent is to correlate many Datasnapshots with a dattime reference, and using the offset of the data to refer to its meaning. This was determined to be the most efficient way to store the data on the back-end, and has now reflected itself into the following structure: public class myDataObject { [DataMember] public SortedDictionary<DateTime, float[]> Pages { get; set; } /// <summary> /// An array that identifies what each position in the array is supposed to be /// </summary> [DataMember] public CounterDescription[] Counters { get; set; } } I will need to expand each of these arrays (float[] and CounterDescription[] ), but whatever data already exists must stay in that relative offset. Which .NET objects support this? I think Array[] , LinkedList<t>, and List<t> Are able to keep the data fixed in the right locations. What do you think?

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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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  • 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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  • 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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  • django image managment

    - by Andrey
    I'am new in django. In my project I'am working with images. I don't know how to organize the management of images. I need to dynamically upload the pictures and resize them. First question - what is the best way to dynamically upload images with progress bar and without flash? I found this and this, but I believe there is a better way. Second question. I have to save one image in different sizes. I won't use these thumbnails on my pages, but another application will. Many clients could upload images at the same time. This means that I can not resize all the images at the same time. How should I organize this process? Is there are a better ready-to-use solution for image management issue?

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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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  • 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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