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• Understanding addSubview: memoryLeak

  - by Leandros

  I don't really understand, why this code leaks. ParentViewController *parentController = [[ParentViewController alloc] init]; ChildViewController *childController = [[ChildViewController alloc] init]; [parentController containerAddChildViewController:childController]; [[self window] setRootViewController:parentController]; - (void)containerAddChildViewController:(UIViewController *)childViewController { [self addChildViewController:childViewController]; [self.view addSubview:childViewController.view]; // Instruments is telling me, the leak occurs here! [childViewController didMoveToParentViewController:self]; } According to Instruments, this line: [self.view addSubview:childViewController.view]; is leaking. The whole code is called once in application:didFinishLaunchingWithOptions:, but it is shown that this code is responsible for 30 leaks (approx. 1.12 kB).

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• Why does my C++ LinkedList cause a EXC_BAD_ACCESS?

  - by Anthony Glyadchenko

  When I call the cmremoveNode method in my LinkedList from outside code, I get an EXC_BAD_ACCESS. /* * LinkedList.h * Lab 6 * * Created by Anthony Glyadchenko on 3/22/10. * Copyright 2010 __MyCompanyName__. All rights reserved. * */ #include <stdio.h> #include <iostream> #include <fstream> #include <iomanip> using namespace std; class ctNode { friend class ctlinkList ; // friend class allowed to access private data private: string sfileWord ; // used to allocate and store input word int iwordCnt ; // number of word occurrances ctNode* ctpnext ; // point of Type Node, points to next link list element }; class ctlinkList { private: ctNode* ctphead ; // initialized by constructor public: ctlinkList () { ctphead = NULL ; } ctNode* gethead () { return ctphead ; } string cminsertNode (string svalue) { ctNode* ctptmpHead = ctphead ; if ( ctphead == NULL ) { // allocate new and set head ctptmpHead = ctphead = new ctNode ; ctphead -> ctpnext = NULL ; ctphead -> sfileWord = svalue ; } else { //find last ctnode do { if ( ctptmpHead -> ctpnext != NULL ) ctptmpHead = ctptmpHead -> ctpnext ; } while ( ctptmpHead -> ctpnext != NULL ) ; // fall thru found last node ctptmpHead -> ctpnext = new ctNode ; ctptmpHead = ctptmpHead -> ctpnext ; ctptmpHead -> ctpnext = NULL ; ctptmpHead -> sfileWord = svalue ; } return ctptmpHead -> sfileWord ; } string cmreturnNode (string svalue) { return NULL; } string cmremoveNode (string svalue) { if (ctphead == NULL) return NULL; ctNode *tmpHead = ctphead; while (tmpHead->sfileWord != svalue || tmpHead->ctpnext != NULL){ tmpHead = tmpHead->ctpnext; } if (tmpHead == NULL){ return NULL; } else { while (tmpHead != NULL){ tmpHead = tmpHead->ctpnext; } } return tmpHead->sfileWord; } string cmlistList () { string tempList; ctNode *tmpHead = ctphead; if (ctphead == NULL){ return NULL; } else{ while (tmpHead != NULL){ cout << tmpHead->sfileWord << " "; tempList += tmpHead->sfileWord; tmpHead = tmpHead -> ctpnext; } } return tempList; } }; Why is this happening?

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• Best way to figure out why didReceiveMemoryWarning is always getting called on a UIViewController

  - by wgpubs

  I have a UIViewController and I'm noticing that I've done something to where the didReceiveMemoryWarning method is getting called every time I run it on an actual device. I've run the project with Run Run With Performance Tool Object Allocations (and Leaks also). There are no leaks but I have no idea how to read or understand the "Object Allocations" data that is displayed. So ... How do I read this information and what is/are the best ways to figure out (and resolve) why this is happening? Thanks

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• Releasing Xmlparser and NSXMLParser objects

  - by erastusnjuki

  How can I release the variables xmlParser and parser safely in the function below? - (id)callRestService: (NSString *) methodName : (NSDictionary *) params { NSURL *url=[self getRestUrl: methodName : params]; XmlParser *xmlParser = [[XmlParser alloc] init]; NSXMLParser *parser = [[NSXMLParser alloc] initWithContentsOfURL:url]; [parser setDelegate:xmlParser]; [parser setShouldProcessNamespaces:NO]; [parser setShouldReportNamespacePrefixes:NO]; [parser setShouldResolveExternalEntities:NO]; [parser parse]; [parser setDelegate:nil]; return xmlParser.dictionaryArray; }

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• Python halts while iteratively processing my 1GB csv file

  - by Dan

  I have two files: metadata.csv: contains an ID, followed by vendor name, a filename, etc hashes.csv: contains an ID, followed by a hash The ID is essentially a foreign key of sorts, relating file metadata to its hash. I wrote this script to quickly extract out all hashes associated with a particular vendor. It craps out before it finishes processing hashes.csv stored_ids = [] # this file is about 1 MB entries = csv.reader(open(options.entries, "rb")) for row in entries: # row[2] is the vendor if row[2] == options.vendor: # row[0] is the ID stored_ids.append(row[0]) # this file is 1 GB hashes = open(options.hashes, "rb") # I iteratively read the file here, # just in case the csv module doesn't do this. for line in hashes: # not sure if stored_ids contains strings or ints here... # this probably isn't the problem though if line.split(",")[0] in stored_ids: # if its one of the IDs we're looking for, print the file and hash to STDOUT print "%s,%s" % (line.split(",")[2], line.split(",")[4]) hashes.close() This script gets about 2000 entries through hashes.csv before it halts. What am I doing wrong? I thought I was processing it line by line. ps. the csv files are the popular HashKeeper format and the files I am parsing are the NSRL hash sets. http://www.nsrl.nist.gov/Downloads.htm#converter UPDATE: working solution below. Thanks everyone who commented! entries = csv.reader(open(options.entries, "rb")) stored_ids = dict((row[0],1) for row in entries if row[2] == options.vendor) hashes = csv.reader(open(options.hashes, "rb")) matches = dict((row[2], row[4]) for row in hashes if row[0] in stored_ids) for k, v in matches.iteritems(): print "%s,%s" % (k, v)

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• Wrapping allocated output parameters with a scoped_ptr/array

  - by Danra

  So, I have some code which looks like this: byte* ar; foo(ar) // Allocates a new[] byte array for ar ... delete[] ar; To make this safer, I used a scoped_array: byte* arRaw; scoped_array ar; foo(arRaw); ar.reset(arRaw); ... // No delete[] The question is, Is there any existing way to do this using just the scoped_array, without using a temporary raw array? I can probably write an in-place "resetter" class, just wondering if the functionality exists and I'm missing it. Thanks, Dan

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• Is there any reasonable use of a function returning an anonymous struct?

  - by Akanksh

  Here is an (artificial) example of using a function that returns an anonymous struct and does "something" useful: #include <iostream> template<typename T> T* func( T* t, float a, float b ) { if(!t) { t = new T; t->a = a; t->b = b; } else { t->a += a; t->b += b; } return t; } struct { float a, b; }* foo(float a, float b) { if(a==0) return 0; return func(foo(a-1,b), a, b); } int main() { std::cout << foo(5,6)->a << std::endl; std::cout << foo(5,6)->b << std::endl; void* v = (void*)(foo(5,6)); float* f = (float*)(v); //[1] delete f now because I know struct is floats only. std::cout << f[0] << std::endl; std::cout << f[1] << std::endl; delete[] f; return 0; } There are a few points I would like to discuss: As is apparent, this code leaks, is there anyway I can NOT leak without knowing what the underlying struct definition is? see Comment [1]. I have to return a pointer to an anonymous struct so I can create an instance of the object within the templatized function func, can I do something similar without returning a pointer? I guess the most important, is there ANY (real-world) use for this at all? As the example given above leaks and is admittedly contrived. By the way, what the function foo(a,b) does is, to return a struct containing two numbers, the sum of all numbers from 1 to a and the product of a and b. EDIT: Maybe the line new T could use a boost::shared_ptr somehow to avoid leaks, but I haven't tried that. Would that work?

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• What could cause a Labwindows/CVI C program to hate the number 2573?

  - by Adam Bard

  Using Windows So I'm reading from a binary file a list of unsigned int data values. The file contains a number of datasets listed sequentially. Here's the function to read a single dataset from a char* pointing to the start of it: function read_dataset(char* stream, t_dataset *dataset){ //...some init, including setting dataset->size; for(i=0;i<dataset->size;i++){ dataset->samples[i] = *((unsigned int *) stream); stream += sizeof(unsigned int); } //... } Where read_dataset in such a context as this: //... char buff[10000]; t_dataset* dataset = malloc( sizeof( *dataset) ); unsigned long offset = 0; for(i=0;i<number_of_datasets; i++){ fseek(fd_in, offset, SEEK_SET); if( (n = fread(buff, sizeof(char), sizeof(*dataset), fd_in)) != sizeof(*dataset) ){ break; } read_dataset(buff, *dataset); // Do something with dataset here. It's screwed up before this, I checked. offset += profileSize; } //... Everything goes swimmingly until my loop reads the number 2573. All of a sudden it starts spitting out random and huge numbers. For example, what should be ... 1831 2229 2406 2637 2609 2573 2523 2247 ... becomes ... 1831 2229 2406 2637 2609 0xDB00000A 0xC7000009 0xB2000008 ... If you think those hex numbers look suspicious, you're right. Turns out the hex values for the values that were changed are really familiar: 2573 -> 0xA0D 2523 -> 0x9DB 2247 -> 0x8C7 So apparently this number 2573 causes my stream pointer to gain a byte. This remains until the next dataset is loaded and parsed, and god forbid it contain a number 2573. I have checked a number of spots where this happens, and each one I've checked began on 2573. I admit I'm not so talented in the world of C. What could cause this is completely and entirely opaque to me.

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• glibc Heap Consistency Checking

  - by idimba

  According to posts from 2008 (I can't find it right now), glibc heap check doesn't work in multithreaded environment. Is it still situation now in 2010? Does heap check enabled by default? (gcc 4.1.2)? I don't set MALLOC_CHECK_, don't aware of calling mcheck(), but still sometimes receive double free glibc error with backtrace. Maybe it's enabled by some ccompilation flag?

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• Optimizing processing and management of large Java data arrays

  - by mikera

  I'm writing some pretty CPU-intensive, concurrent numerical code that will process large amounts of data stored in Java arrays (e.g. lots of double[100000]s). Some of the algorithms might run millions of times over several days so getting maximum steady-state performance is a high priority. In essence, each algorithm is a Java object that has an method API something like: public double[] runMyAlgorithm(double[] inputData); or alternatively a reference could be passed to the array to store the output data: public runMyAlgorithm(double[] inputData, double[] outputData); Given this requirement, I'm trying to determine the optimal strategy for allocating / managing array space. Frequently the algorithms will need large amounts of temporary storage space. They will also take large arrays as input and create large arrays as output. Among the options I am considering are: Always allocate new arrays as local variables whenever they are needed (e.g. new double[100000]). Probably the simplest approach, but will produce a lot of garbage. Pre-allocate temporary arrays and store them as final fields in the algorithm object - big downside would be that this would mean that only one thread could run the algorithm at any one time. Keep pre-allocated temporary arrays in ThreadLocal storage, so that a thread can use a fixed amount of temporary array space whenever it needs it. ThreadLocal would be required since multiple threads will be running the same algorithm simultaneously. Pass around lots of arrays as parameters (including the temporary arrays for the algorithm to use). Not good since it will make the algorithm API extremely ugly if the caller has to be responsible for providing temporary array space.... Allocate extremely large arrays (e.g. double[10000000]) but also provide the algorithm with offsets into the array so that different threads will use a different area of the array independently. Will obviously require some code to manage the offsets and allocation of the array ranges. Any thoughts on which approach would be best (and why)?

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• Python ValueError: not allowed to raise maximum limit

  - by Ricky Bobby

  I'm using python 2.7.2 on mac os 10.7.3 I'm doing a recursive algorithm in python with more than 50 000 recursion levels. I tried to increase the maximum recursion level to 1 000 000 but my python shell still exit after 18 000 recursion levels. I tried to increase the resources available : import resource resource.setrlimit(resource.RLIMIT_STACK, (2**29,-1)) sys.setrecursionlimit(10**6) and I get this error : Traceback (most recent call last): File "<pyshell#58>", line 1, in <module> resource.setrlimit(resource.RLIMIT_STACK,(2**29,-1)) ValueError: not allowed to raise maximum limit I don't know why I cannot raise the maximum limit ? thanks for your suggestions .

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• What is the difference between these two different lines of Objective-C, and why does one work and n

  - by jrtc27

  If I try and release tempSeedsArray after seedsArray = tempSeedsArray , I get an EXEC_BAD_ACCESS, and Instruments shows that tempSeedsArray has been released twice. Here is my viewWillAppear method: - (void)viewWillAppear:(BOOL)animated { NSString *arrayFilePath = [[NSBundle mainBundle] pathForResource:@"SeedsArray" ofType:@"plist"]; NSLog(@"HIT!"); NSMutableArray *tempSeedsArray = [[NSMutableArray alloc] initWithContentsOfFile:arrayFilePath]; seedsArray = tempSeedsArray; NSLog(@"%u", [seedsArray retainCount]); [seedsArray sortUsingSelector:@selector(localizedCaseInsensitiveCompare:)]; [super viewWillAppear:animated]; } seedsArray is an NSMutableArray set as a nonatomic and a retain property, and is synthesised. However, if I change seedsArray = tempSeedsArray to self.seedsArray = tempSeedsArray (or [self seedsArray] = tempSeedsArray etc.), I can release tempSeedsArray. Could someone please explain simply to me why this is, as I am very confused! Thanks

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• UIImage imageNamed not autoreleasing correctly

  - by MrHen

  For some reason, the retain/release behavior in the following code has me completely baffled. selectedImage = [UIImage imageNamed:@"icon_72.png"]; [selectedImage release]; This should break but does not. Why? I thought imageNamed autoreleased itself which means the release here is redundant and should break when the autorelease occurs. Here are snippets relevant to selectedImage from the .h and .m files: @property (nonatomic, readonly) UIImage *selectedImage; @synthesize delegate, selectedImage, spacerBottom, currentIndex; Other notes, this does break: selectedImage = [UIImage imageNamed:@"icon_72.png"]; [selectedImage release]; [selectedImage release]; //objc[55541]: FREED(id): message release sent to freed object=0x59245b0 //Program received signal: “EXC_BAD_INSTRUCTION”. As does this: selectedImage = [UIImage imageNamed:@"icon_72.png"]; [selectedImage release]; [selectedImage autorelease]; //objc[55403]: FREED(id): message autorelease sent to freed object=0x59b54c0 //Program received signal: “EXC_BAD_INSTRUCTION”. And so does the following: selectedImage = [UIImage imageNamed:@"icon_72.png"]; [selectedImage autorelease]; [selectedImage release]; //objc[55264]: FREED(id): message release sent to freed object=0x592c9a0 //Program received signal: “EXC_BAD_INSTRUCTION”. And so does this: selectedImage = [UIImage imageNamed:@"icon_72.png"]; [selectedImage autorelease]; [selectedImage autorelease]; //objc[55635]: FREED(id): message release sent to freed object=0x5b305d0 //Program received signal: “EXC_BAD_INSTRUCTION”.

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• When modern computers boot, what initial setup of RAM do they execute, and how does it exactly work?

  - by user272840

  I know the title reeks of confusion, and some of you might assume I am just wondering about how the computer boots in general, but I'm not. But I'll sort this out for you people now: 1.Onboard firmware is how mostly all modern computer devices work, whether or not with EFI/UEFI(even without "onboard firmware", older computers still employed bank switching, or similar methods with snap-in firmware, cartridges, etc.) 2.On startup there is no "programs" running in the traditional sense yet, i.e. no kernel, OS, user-applications; all of the instructions, especially the very first instruction, is specified by the Instruction Pointer, I am guessing. How is the IP/PC/etc. set to first point to an address for a BIOS/firmware/etc. instruction, and how do the BIOS instructions map themself out in memory prior to startup? 3.Aside from MMIO, BIOS uses certain RAM addresses to have instructions. The big ? comes in when I ask this ... how does BIOS do this? Conclusion: I am assuming that with the very first instruction there is an initial hardware setup for BIOS prior to complete OS bootup. What I want to know is if it's hardware engineered to always work this way, if there's another step in this bootup method I am missing, a gap of information I am unaware of, or how this all works from the very first instruction, and the RAM data itself.

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• return value (not a reference) from the function, bound to a const reference in the calling function

  - by brainydexter

  "If you return a value (not a reference) from the function, then bind it to a const reference in the calling function, its lifetime would be extended to the scope of the calling function." So: const BoundingBox Player::GetBoundingBox(void) { return BoundingBox( &GetBoundingSphere() ); } Returns a value of type const BoundingBox from function GetBoundingBox() Called function: (From within function Update() the following is called:) variant I: (Bind it to a const reference) const BoundingBox& l_Bbox = l_pPlayer->GetBoundingBox(); variant II: (Bind it to a const copy) const BoundingBox l_Bbox = l_pPlayer->GetBoundingBox(); Both work fine and I don't see the l_Bbox object going out of scope. (Though, I understand in variant one, the copy constructor is not called and thus is slightly better than variant II). Also, for comparison, I made the following changes. BoundingBox Player::GetBoundingBox(void) { return BoundingBox( &GetBoundingSphere() ); } with Variants: I BoundingBox& l_Bbox = l_pPlayer->GetBoundingBox(); and II: BoundingBox l_Bbox = l_pPlayer->GetBoundingBox(); The objet l_Bbox still does not out scope. So, I don't see how "bind it to a const reference in the calling function, its lifetime would be extended to the scope of the calling function", really extends the lifetime of the object to the scope of the calling function ? Am I missing something trivial here..please explain .. Thanks a lot

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• How much space does "variable name" takes ?

  - by Ravi Gupta

  I have 2 variable like below char s='s'; char Kaazoooombaa ='s'; how can I know which variable is consuming how much space ?

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• alignment and granularity of mmap

  - by OwnWaterloo

  I am confused by the specification of mmap. Let pa be the return address of mmap (the same as the specification) pa = mmap(addr, len, prot, flags, fildes, off); In my opinion after the function call succeed the following range is valid [ pa, pa+len ) My question is whether the range of the following is still valid? [ round_down(pa, pagesize) , round_up(pa+len, pagesize) ) [ base, base + size ] for short That is to say: is the base always aligned on the page boundary? is the size always a multiple of pagesize (the granularity is pagesize in other words) Thanks for your help. I think it is implied in this paragraph : The off argument is constrained to be aligned and sized according to the value returned by sysconf() when passed _SC_PAGESIZE or _SC_PAGE_SIZE. When MAP_FIXED is specified, the application shall ensure that the argument addr also meets these constraints. The implementation performs mapping operations over whole pages. Thus, while the argument len need not meet a size or alignment constraint, the implementation shall include, in any mapping operation, any partial page specified by the range [pa,pa+len). But I'm not sure and I do not have much experience on POSIX. Please show me some more explicit and more definitive evidence Or show me at least one system which supports POSIX and has different behavior Thanks agian.

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• Why isn't 'Low Fragmentation Heap' LFH enabled by default on Windows Server 2003?

  - by James Wiseman

  I've been investigating an issue with a production Classic ASP website running on IIS6 which seems indicative of memory fragmentation. One of the suggestions of how to ameliorate this came from Stackoverflow: How can I find why some classic asp pages randomly take a real long time to execute?. It suggested flipping a setting in the site's global.asa file to 'turn on' Low Fragmentation Heap (LFH). The following code (with a registered version of the accompanying DLL) did the trick. Set LFHObj=CreateObject("TURNONLFH.ObjTurnOnLFH") LFHObj.TurnOnLFH() application("TurnOnLFHResult")=CStr(LFHObj.TurnOnLFHResult) (Really the code isn't that important to the question). An author of a linked post reported a seemingly magic resolution to this issue, and, reading around a little more, I discovered that this setting is enabled by default on Windows Server 2008. So, naturally, this left me a little concerned: Why is this setting not enabled by default on 2003, or If it works in 2008 why have Microsoft not issued a patch to enable it by default on 2003? I suspect the answer to the above is the same for both (if there is one). Obviously, we're testing it in a non-production environment, and doing an array of metrics and comparisons to deem if it does help us. But aside from this I'm really just trying to understand if there's any technical reason why we should do this, or if there are any gotchas that we need to be aware of.

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• How to use C to write to flash drive bootsector despite error 'Failed to open file to write.:Permiss

  - by updateraj

  My goal is to manipulate the boot-sector in my flashdrive (volume E:) I am using XP. I am able to read the boot-sector FILE *fp_read = fopen("\\\\.\\E:", "rb"); /* Able to proceed to read boot sector */ however i am not able to open the file to write using fopen in 'wb' mode. FILE *fp_read = fopen("\\\\.\\E:", "wb"); /* Unable to proceed due to Failed to open file to write.:Permission Denied */ The flash-drive is not in use at the moment of execution. Hex-editors are able to manipulated boot sector etc, i believe it possible to do so in c. Any suggestion or insight to overcome the access problem so as to be able to write?

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• OpenGL Video RAM Limits

  - by Tamir

  I have been trying to make a Cross-platform 2D Online Game, and my maps are made of tiles. My tileset, which I render the tiles from, is quite huge. I wanted to know how can I disable hardware rendering, or at least making it more capable. Hence, I wanted to know what are the basic limits of the video ram, as far as I know, Direct3D has a texture size limits (by that I don't mean the power-of-two texture sizes).

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• PC can't detect second RAM installed

  - by kulwinder

  I have PC with 512 MB RAM installed (motherboard manufacture MICRO STAR, chipset P4M800), pc was running very slow so I decided to upgrade the ram. I installed CPU-Z and check the ram installed on the machine, also had a look at the stick installed. 512 MB PC 3200 400 MHz DDR but my mother supports 200 MHz and it was working ok. So I bought 2GB which I checked on manual that it support upto 2 GB Ram. So I installed 2GB PC 3200 400 MHz same as the old one, I plugged in both eventhough motherboard only support upto 2 GB but system spec only shows 512 (deducts 64 MB shared vga memory) I checked on CPU-Z, it detects both, slot 1 512 MB, slot 2 2048 MB, comparing screen for both slots, both the same, volt 2.5, frequency 166 MHz and 200MHz, only difference on those is 2gb ram shows under timings table 133MHz 166 MHz and 200MHz but 512 MB shows only 166MHz and 200MHz. I checked on Google and can't seems to figure out whats wrong with it. If I only plug in 2GB. Pc doesn't boot up like ram not working.With only 512 MB plugged in seems ok. Please help.

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• NSMutableDictionary isn't stick around long enough

  - by Sean Danzeiser

  Sorry, beginner here . . . So I create an NSMutableDictionary in my app delegate when the application launches, and then later pass it on to a view controller, as it contains options for the VC like a background image, a url I want to parse, etc. Anyway, i wrote a custom init method for the VC, initWithOptions, where I pass the dictionary on. I'm trying to use this dictionary later on in other methods - so I created a NSMutableDictionary property for my VC and am trying to store the passed options dictionary there. However, when I go to get the contents of that property in later methods, it returns null. If i access it from the init method, it works. heres some sample code: -(id)initWithOptions:(NSMutableDictionary *)options { self = [super init]; if (self) { // Custom initialization self.optionsDict = [[NSMutableDictionary alloc]initWithDictionary:options]; NSLog(@"dictionary in init method %@",self.optionsDict); that NSLog logs the contents of the dictionary, and it looks like its working. then later when I do this: - (void)viewDidLoad { SDJConnection *connection = [[SDJConnection alloc]init]; self.dataArray = [connection getEventInfoWithURL:[dict objectForKey:@"urlkey"]]; NSLog(@"dictionary in connection contains: %@", [dict objectForKey:@"urlkey"]); [_tableView reloadData]; the dictionary returns null. Ive tried adjusting the property attributes, and it didn't work with either strong or retain. Any ideas?? THANKS!!

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• Delphi Unicode String Type Stored Directly at its Address (or "Unicode ShortString")

  - by Andreas Rejbrand

  I want a string type that is Unicode and that stores the string directly at the adress of the variable, as is the case of the (Ansi-only) ShortString type. I mean, if I declare a S: ShortString and let S := 'My String', then, at @S, I will find the length of the string (as one byte, so the string cannot contain more than 255 characters) followed by the ANSI-encoded string itself. What I would like is a Unicode variant of this. That is, I want a string type such that, at @S, I will find a unsigned 32-bit integer (or a single byte would be enough, actually) containing the length of the string in bytes (or in characters, which is half the number of bytes) followed by the Unicode representation of the string. I have tried WideString, UnicodeString, and RawByteString, but they all appear only to store an adress at @S, and the actual string somewhere else (I guess this has do do with reference counting and such). Update: The most important reason for this is probably that it would be very problematic if sizeof(string) were variable. I suspect that there is no built-in type to use, and that I have to come up with my own way of storing text the way I want (which actually is fun). Am I right? Update I will, among other things, need to use these strings in packed records. I also need manually to read/write these strings to files/the heap. I could live with fixed-size strings, such as <= 128 characters, and I could redesign the problem so it will work with null-terminated strings. But PChar will not work, for sizeof(PChar) = 1 - it's merely an address. The approach I eventually settled for was to use a static array of bytes. I will post my implementation as a solution later today.

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• Should boost library be dependent on structure member alignments?

  - by Sorin Sbarnea

  I found, the hard way, that at least boost::program_options is dependent of the compiler configured structure member alignment. If you build boost using default settings and link it with a project using 4 bytes alignment (/Zp4) it will fail at runtime (made a minimal test with program_options). Boost will generate an assert indicating a possible bad calling convention but the real reason is the structure member alignment. Is there any way to prevent this? If the alignment makes the code incompatible shouldn't this be included in library naming?

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• Disadvantages of enabling 'Low Fragmentation Heap' LFH on Windows Server 2003?

  - by James Wiseman

  I've been investigating an issue with a production Classic ASP website running on IIS6 which seems indicative of memory fragmentation. One of the suggestions of how to ameliorate this came from Stackoverflow: How can I find why some classic asp pages randomly take a real long time to execute?. It suggested flipping a setting in the site's global.asa file to 'turn on' Low Fragmentation Heap (LFH). The following code (with a registered version of the accompanying DLL) did the trick. Set LFHObj=CreateObject("TURNONLFH.ObjTurnOnLFH") LFHObj.TurnOnLFH() application("TurnOnLFHResult")=CStr(LFHObj.TurnOnLFHResult) (Really the code isn't that important to the question). An author of a linked post reported a seemingly magic resolution to this issue, and, reading around a little more, I discovered that this setting is enabled by default on Windows Server 2008. So, naturally, this left me a little concerned: Why is this setting not enabled by default on 2003, or If it works in 2008 why have Microsoft not issued a patch to enable it by default on 2003? I suspect the answer to the above is the same for both (if there is one). Obviously, we're testing it in a non-production environment, and doing an array of metrics and comparisons to deem if it does help us. But aside from this I'm really just trying to understand if there's any technical reason why we should do this, or if there are any gotchas that we need to be aware of.

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