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• Why is DivMod Limited to Words (<=65535)?

  - by Andreas Rejbrand

  In Delphi, the declaration of the DivMod function is procedure DivMod(Dividend: Cardinal; Divisor: Word; var Result, Remainder: Word); Thus, the divisor, result, and remainder cannot be grater than 65535, a rather severe limitation. Why is this? Why couldn't the delcaration be procedure DivMod(Dividend: Cardinal; Divisor: Cardinal; var Result, Remainder: Cardinal); The procedure is implemented using assembly, and is therefore probably extremely fast. Would it not be possible for the code PUSH EBX MOV EBX,EDX MOV EDX,EAX SHR EDX,16 DIV BX MOV EBX,Remainder MOV [ECX],AX MOV [EBX],DX POP EBX to be adapted to cardinals? How much slower is the naïve attempt procedure DivModInt(const Dividend: integer; const Divisor: integer; out result: integer; out remainder: integer); begin result := Dividend div Divisor; remainder := Dividend mod Divisor; end; that is not (?) limited to 16-bit integers?

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• Does operator precedence in C++ differ for pointers and iterators?

  - by oraz

  The code below demonstrates this difference: #include <iostream> #include <string> int main() { char s[] = "ABCD"; std::string str(s); char *p = s; while(*p) { *p++ = tolower(*p); // <-- incr after assignment } std::cout << s << std::endl; std::string::iterator it = str.begin(), end = str.end(); while(it != end) { *it++ = tolower(*it); // <-- incr before assignment ? } std::cout << str << std::endl; return 0; } the code above outputs: abcd bcd if we separate assignment operation and increment operator: while(it != end) { *it = tolower(*it); // <-- incr before assignment ? it++; } the output will be as expected. What's wrong with the original code? $ g++ --version g++ (GCC) 3.4.4 (cygming special, gdc 0.12, using dmd 0.125) Copyright (C) 2004 Free Software Foundation, Inc.

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• Unsure how to come up with a good design

  - by Mewzer

  Hello there, I am having trouble coming up with a good design for a group of classes and was hoping that someone could give me some guidance on best practices. I have kept the classes and member functions generic to make the problem simpler. Essentially, I have three classes (lets call them A, B, and C) as follows: class A { ... int GetX( void ) const { return x; }; int GetY( void ) const { return y; }; private: B b; // NOTE: A "has-a" B int x; int y; }; class B { ... void SetZ( int value ) { z = value }; private: int z; C c; // NOTE: B "has-a" C }; class C { private: ... void DoSomething(int x, int y){ ... }; void DoSomethingElse( int z ){ ... }; }; My problem is as follows: Class A uses its member variables "x" and "y" a lot internally. Class B uses its member variable "z" a lot internally. Class B needs to call C::DoSomething(), but C::DoSomething() needs the values of X and Y in class A passed in as arguments. C::DoSomethingElse() is called from say another class (e.g. D), but it needs to invoke SetZ() in class B!. As you can see, it is a bit of a mess as all the classes need information from one another!. Are there any design patterns I can use?. Any ideas would be much appreciated ....

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• Objective-C Result from a Static Method saved to class instance variable giving "EXC_BAD_ACCESS" when used.

  - by KinGBin

  I am trying to store the md5 string as a class instance variable instead of the actual password. I have a static function that will return a md5 string which I'm trying to store in an instance variable instead of the actual password. I have the following setter for my class instance variable: -(void)setPassword:(NSString *)newpass{ if(newpass != password){ password = [utils md5HexDigest:newpass]; } } This will pass back the correct md5 string and save it to the password variable in my init function: [self setPassword:pword];. If I call another instance method and try to access self.password" I will get "EXC_BAD_ACCESS". I understand that the memory is getting released, but I have no clue to make sure it stays. I have tried alloc init with autorelease with no luck. This is the md5HexDigest function getting called during the init (graciously found in another stackoverflow question): + (NSString*)md5HexDigest:(NSString*)input { const char* str = [input UTF8String]; unsigned char result[CC_MD5_DIGEST_LENGTH]; CC_MD5(str, strlen(str), result); NSMutableString *ret = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH*2]; for(int i = 0; i<CC_MD5_DIGEST_LENGTH; i++) { [ret appendFormat:@"%02x",result[i]]; } return ret; } Any help/pointers would be greatly appreciated. I would rather have the md5 string saved in memory than the actual password calling the md5 every time I needed to use the password. Thanks in advance.

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• How to copy_if from map to vector?

  - by VJo

  I'd like to copy values that match a predicate (equal ints) from a map<string,int> to a vector<int>. This is what I tried: #include <map> #include <vector> #include <algorithm> int main() { std::vector< int > v; std::map< std::string, int > m; m[ "1" ] = 1; m[ "2" ] = 2; m[ "3" ] = 3; m[ "4" ] = 4; m[ "5" ] = 5; std::copy_if( m.begin(), m.end(), v.begin(), [] ( const std::pair< std::string,int > &it ) { return ( 0 == ( it.second % 2 ) ); } ); } The error message from g++ 4.6.1 is : error: cannot convert 'std::pair<const std::basic_string<char>, int>' to 'int' in assignment Is there a way to adjust the example to do the above copy?

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• "Address of" (&) an array / address of being ignored be gcc?

  - by dbarbosa

  Hi, I am a teaching assistant of a introductory programming course, and some students made this type of error: char name[20]; scanf("%s",&name); which is not surprising as they are learning... What is surprising is that, besides gcc warning, the code works (at least this part). I have been trying to understand and I wrote the following code: void foo(int *str1, int *str2) { if (str1 == str2) printf("Both pointers are the same\n"); else printf("They are not the same\n"); } int main() { int test[50]; foo(&test, test); if (&test == test) printf("Both pointers are the same\n"); else printf("They are not the same\n"); } Compiling and executing: $ gcc test.c -g test.c: In function ‘main’: test.c:12: warning: passing argument 1 of ‘foo’ from incompatible pointer type test.c:13: warning: comparison of distinct pointer types lacks a cast $ ./a.out Both pointers are the same Both pointers are the same Can anyone explain why they are not different? I suspect it is because I cannot get the address of an array (as I cannot have & &x), but in this case the code should not compile.

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• C#, How to download file into string with progress callback?

  - by Kaminari

  I would like to use the WebClient (or there is another better option?) but there is a problem. I understand that opening up the stream takes some time and this can not be avoided. However, reading it takes a strangely much more amount of time compared to read it entirely immediately. Of course it's not working good because i'm not so familiar with streams. Is there a best way to do this? I mean two ways, to string and to file. Progress is my own delegate and it's working good. FIRST UPDATE: Ok, now i got something like this and it seems to work but still slow: System.Net.WebClient client = new System.Net.WebClient(); System.IO.Stream streamRemote = client.OpenRead(new Uri(URL)); if (savePath == null) { StreamReader reader = new StreamReader(streamRemote); int iByteSize = 0; byte[] byteBuffer = new byte[iSize]; char[] charBuffer = new char[iSize]; StringBuilder sb = new StringBuilder(); while ((iByteSize = reader.Read(charBuffer, 0, iSize)) > 0) { sb.Append(charBuffer, 0, iByteSize); iRunningByteTotal += iByteSize; float dIndex = (float)(iRunningByteTotal); float dTotal = (float)byteBuffer.Length; float dProgressPercentage = (dIndex / dTotal); float iProgressPercentage = (dProgressPercentage * 100); if (Progress != null) Progress(iProgressPercentage); } result = sb.ToString(); } Im wondering about DownloadStringAsync method?

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• C++, overloading std::swap, compiler error, VS 2010

  - by Ian

  I would like to overload std::swap in my template class. In the following code (simplified) #ifndef Point2D_H #define Point2D_H template <class T> class Point2D { protected: T x; T y; public: Point2D () : x ( 0 ), y ( 0 ) {} Point2D( const T &x_, const T &y_ ) : x ( x_ ), y ( y_ ) {} .... public: void swap ( Point2D <T> &p ); }; template <class T> inline void swap ( Point2D <T> &p1, Point2D <T> &p2 ) { p1.swap ( p2 ); } namespace std { template <class T> inline void swap ( Point2D <T> &p1, Point2D <T> &p2 ) { p1.swap ( p2 ); } } template <class T> void Point2D <T>::swap ( Point2D <T> &p ) { using (std::swap); swap ( x, p.x ); swap ( y, p.y ); } #endif there is a compiler error (only in VS 2010): error C2668: 'std::swap' : ambiguous call to overloaded I do not know why, std::swap should be overoaded... Using g ++ code works perfectly. Without templates (i.e. Point2D is not a template class) this code also works.. Thanks for your help.

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• Parallelize or vectorize all-against-all operation on a large number of matrices?

  - by reve_etrange

  I have approximately 5,000 matrices with the same number of rows and varying numbers of columns (20 x ~200). Each of these matrices must be compared against every other in a dynamic programming algorithm. In this question, I asked how to perform the comparison quickly and was given an excellent answer involving a 2D convolution. Serially, iteratively applying that method, like so list = who('data_matrix_prefix*') H = cell(numel(list),numel(list)); for i=1:numel(list) for j=1:numel(list) if i ~= j eval([ 'H{i,j} = compare(' char(list(i)) ',' char(list(j)) ');']); end end end is fast for small subsets of the data (e.g. for 9 matrices, 9*9 - 9 = 72 calls are made in ~1 s). However, operating on all the data requires almost 25 million calls. I have also tried using deal() to make a cell array composed entirely of the next element in data, so I could use cellfun() in a single loop: # who(), load() and struct2cell() calls place k data matrices in a 1D cell array called data. nextData = cell(k,1); for i=1:k [nextData{:}] = deal(data{i}); H{:,i} = cellfun(@compare,data,nextData,'UniformOutput',false); end Unfortunately, this is not really any faster, because all the time is in compare(). Both of these code examples seem ill-suited for parallelization. I'm having trouble figuring out how to make my variables sliced. compare() is totally vectorized; it uses matrix multiplication and conv2() exclusively (I am under the impression that all of these operations, including the cellfun(), should be multithreaded in MATLAB?). Does anyone see a (explicitly) parallelized solution or better vectorization of the problem?

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• Know the row with max characters (C)

  - by l_core

  I have wrote a program in C, to find the row with the max number of characters. Here is the code #include <stdio.h> #include <stdlib.h> #include <ctype.h> #include <string.h> int main (int argc, char *argv[]) { char c; /* used to store the character with getc */ int c_tot = 0, c_rig = 0, c_max = 0; /* counters of characters*/ int r_tot = 0; /* counters of rows */ FILE *fptr; fptr = fopen(argv[1], "r"); if (fptr == NULL || argc != 2) { printf ("Error opening the file %s\n'", argv[1]); exit(EXIT_FAILURE); } while ( (c = getc(fptr)) != EOF) { if (c != ' ' && c != '\n') { c_tot++; c_rig++; } if (c == '\n') { r_tot++; if (c_rig > c_max) c_max = c_rig; c_rig = 0; } } printf ("Total rows: %d\n", r_tot); printf ("Total characters: %d\n", c_tot); printf ("Total characters in a row: %d\n", c_max); printf ("Average number of characters on a row: %d\n", (c_tot/r_tot)); printf ("The row with max characters is: %s\n", ??????) return 0; } I can easily find the row with the highest number of characters but how can i print that out? Thank You Folks

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• ARC and __unsafe_unretained

  - by J Shapiro

  I think I have a pretty good understanding of ARC and the proper use cases for selecting an appropriate lifetime qualifiers (__strong, __weak, __unsafe_unretained, and __autoreleasing). However, in my testing, I've found one example that doesn't make sense to me. As I understand it, both __weak and __unsafe_unretained do not add a retain count. Therefore, if there are no other __strong pointers to the object, it is instantly deallocated. The only difference in this process is that __weak pointers are set to nil, and __unsafe_unretained pointers are left alone. If I create a __weak pointer to a simple, custom object (composed of one NSString property), I see the expected (null) value when trying to access a property: Test * __weak myTest = [[Test alloc] init]; myTest.myVal = @"Hi!"; NSLog(@"Value: %@", myTest.myVal); // Prints Value: (null) Similarly, I would expect the __unsafe_unretained lifetime qualifier to cause a crash, due to the resulting dangling pointer. However, it doesn't. In this next test, I see the actual value: Test * __unsafe_unretained myTest = [[Test alloc] init]; myTest.myVal = @"Hi!"; NSLog(@"Value: %@", myTest.myVal); // Prints Value: Hi! Why doesn't the __unsafe_unretained object become deallocated?

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• C++ Type error with Object versus Object reference

  - by muddybruin

  I have the following function (which worked in Visual Studio): bool Plane::contains(Vector& point){ return normalVector.dotProduct(point - position) < -doubleResolution; } When I compile it using g++ version 4.1.2 , I get the following error: Plane.cpp: In member function âvirtual bool Plane::contains(Vector&)â: Plane.cpp:36: error: no matching function for call to âVector::dotProduct(Vector)â Vector.h:19: note: candidates are: double Vector::dotProduct(Vector&) So as you can see, the compiler thinks (point-position) is a Vector but it's expecting Vector&. What's the best way to fix this? I verified that this works: Vector temp = point-position; return normalVector.dotProduct(temp) < -doubleResolution; But I was hoping for something a little bit cleaner. I heard a suggestion that adding a copy constructor might help. So I added a copy constructor to Vector (see below), but it didn't help. Vector.h: Vector(const Vector& other); Vector.cpp: Vector::Vector(const Vector& other) :x(other.x), y(other.y), z(other.z), homogenous(other.homogenous) { }

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• How to speed-up a simple method? (possibily without changing interfaces or data structures)

  - by baol

  Hello. I have some data structures: all_unordered_mordered_m is a big vector containing all the strings I need (all different) ordered_m is a small vector containing the indexes of a subset of the strings (all different) in the former vector position_m maps the indexes of objects from the first vector to their position in the second one. The string_after(index, reverse) method returns the string referenced by ordered_m after all_unordered_m[index]. ordered_m is considered circular, and is explored in natural or reverse order depending on the second parameter. The code is something like the following: struct ordered_subset { // [...] std::vector<std::string>& all_unordered_m; // size = n >> 1 std::vector<size_t> ordered_m; // size << n std::map<size_t, size_t> position_m; // positions of strings in ordered_m const std::string& string_after(size_t index, bool reverse) const { size_t pos = position_m.find(index)->second; if(reverse) pos = (pos == 0 ? orderd_m.size() - 1 : pos - 1); else pos = (pos == ordered.size() - 1 ? 0 : pos + 1); return all_unordered_m[ordered_m[pos]]; } }; Given that: I do need all of the data-structures for other purposes; I cannot change them because I need to access the strings: by their id in the all_unordered_m; by their index inside the various ordered_m; I need to know the position of a string (identified by it's position in the first vector) inside ordered_m vector; I cannot change the string_after interface without changing most of the program. How can I speed up the string_after method that is called billions of times and is eating up about 10% of the execution time?

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• Replace occurance of character with all letters in the alphabet

  - by McAvoy

  I have created a scrabble game with a computer opponent. If a blank tile is found in the computer's rack during the word generation if needs to be swapped out for every letter in the alphabet. I have my current solution to solve this problem below, but was wondering if there is a better more efficient way to accomplish this task. if (str.Contains("*")) { char c = 'A'; String made = ""; while(c < 'Z') { made = str.ReplaceFirst("*", c.ToString()); if (!made.Contains("*")) { wordsMade.Add(made); if (theGame.theTrie.Search(made) == Trie.SearchResults.Found) { validWords.Add(made); } } else { char ch = 'A'; String made2 = ""; while (ch < 'Z') { made2 = made.ReplaceFirst("*", c.ToString()); wordsMade.Add(made2); if (theGame.theTrie.Search(made2) == Trie.SearchResults.Found) { validWords.Add(made2); } ch++; } } c++; }

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• Difference between these two functions that find Palindromes....

  - by Moin

  I wrote a function to check whether a word is palindrome or not but "unexpectedly", that function failed quite badly, here it is: bool isPalindrome (const string& s){ string reverse = ""; string original = s; for (string_sz i = 0; i != original.size(); ++i){ reverse += original.back(); original.pop_back(); } if (reverse == original) return true; else return false; } It gives me "string iterator offset out of range error" when you pass in a string with only one character and returns true even if we pass in an empty string (although I know its because of the intialisation of the reverse variable) and also when you pass in an unassigned string for example: string input; isPalindrome(input); Later, I found a better function which works as you would expect: bool found(const string& s) { bool found = true; for (string::const_iterator i = s.begin(), j = s.end() - 1; i < j; ++i, --j) { if (*i != *j) found = false; } return found; } Unlike the first function, this function correctly fails when you give it an unassigned string variable or an empty string and works for single characters and such... So, good people of stackoverflow please point out to me why the first function is so bad... Thank You.

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• How to implement tokenizer.rbegin() and rend() for boost::tokenizer ?

  - by Chan

  Hello everyone, I'm playing around with boost::tokenizer however I realize that it does not support rbegin() and rend(). I would like to ask how can I add these two functions to the existing class? This is from the boost site: #include <iostream> #include <string> #include <boost/tokenizer.hpp> using namespace std; using namespace boost; int main() { string str( "12/12/1986" ); typedef boost::tokenizer<boost::char_separator<char>> tokenizer; boost::char_separator<char> sep( "/" ); tokenizer tokens( str, sep ); cout << *tokens.begin() << endl; // cout << *tokens.rbegin() << endl; How could I implement this? return 0; }

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• Using the read function to read in a file.

  - by robUK

  Hello, gcc 4.4.1 I am using the read function to read in a wave file. However, when it gets to the read function. Execution seems to stop and freezes. I am wondering if I am doing anything wrong with this. The file size test-short.wave is: 514K. What I am aiming for is to read the file into the memory buffer chunks at a time. Currently I just testing this. Many thanks for any suggestions, #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <fcntl.h> #include <string.h> #include <unistd.h> int main(void) { char buff = malloc(10240); int32_t fd = 0; int32_t bytes_read = 0; char *filename = "test-short.wav"; /* open wave file */ if((fd = (open(filename, O_RDWR)) == -1)) { fprintf(stderr, "open [ %s ]\n", strerror(errno)); return 1; } printf("Opened file [ %s ]\n", filename); printf("sizeof(buff) [ %d ]\n", sizeof(buff)); printf("strlen(buff) [ %d ]\n", strlen(buff)); bytes_read = read(fd, buff, sizeof(buff)); printf("Bytes read [ %d ]\n", bytes_read); return 0; }

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• (C++) Loading a file into a vector

  - by Alden

  This is probably a simple question, however I am new to C++ and I cannot figure this out. I am trying to load a binary file and load each byte to a vector. This works fine with a small file, but when I try to read larger than 410 bytes the program crashes and says: This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. I am using code::blocks on windows. This is the code: #include <iostream> #include <fstream> #include <vector> using namespace std; int main() { std::vector<char> vec; std::ifstream file; file.exceptions( std::ifstream::badbit | std::ifstream::failbit | std::ifstream::eofbit); file.open("file.bin"); file.seekg(0, std::ios::end); std::streampos length(file.tellg()); if (length) { file.seekg(0, std::ios::beg); vec.resize(static_cast<std::size_t>(length)); file.read(&vec.front(), static_cast<std::size_t>(length)); } int firstChar = static_cast<unsigned char>(vec[0]); cout << firstChar <<endl; return 0; } Thank you for your help!

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• Passing Data to Multi Threads

  - by alaamh

  I study this code from some book: #include <pthread.h> #include <stdio.h> /* Parameters to print_function. */ struct char_print_parms { /* The character to print. */ char character; /* The number of times to print it. */ int count; }; /* Prints a number of characters to stderr, as given by PARAMETERS, which is a pointer to a struct char_print_parms. */ void* char_print(void* parameters) { /* Cast the cookie pointer to the right type. */ struct char_print_parms* p = (struct char_print_parms*) parameters; int i; for (i = 0; i < p->count; ++i) fputc(p->character, stderr); return NULL; } /* The main program. */ int main() { pthread_t thread1_id; pthread_t thread2_id; struct char_print_parms thread1_args; struct char_print_parms thread2_args; /* Create a new thread to print 30,000 ’x’s. */ thread1_args.character = 'x'; thread1_args.count = 30000; pthread_create(&thread1_id, NULL, &char_print, &thread1_args); /* Create a new thread to print 20,000 o’s. */ thread2_args.character = 'o'; thread2_args.count = 20000; pthread_create(&thread2_id, NULL, &char_print, &thread2_args); usleep(20); return 0; } after running this code, I see different result each time. and some time corrupted result. what is wrong and what the correct way to do that?

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• Pair equal operator overloading for inserting into set

  - by Petwoip

  I am trying to add a pair<int,int> to a set. If a pair shares the same two values as another in the set, it should not be inserted. Here's my non-working code: typedef std::pair<int, int> PairInt; template<> bool std::operator==(const PairInt& l, const PairInt& r) { return (l.first == r.first && l.second == r.second) || (l.first == r.second && l.second == r.first); } int main() { std::set<PairInt> intSet; intSet.insert(PairInt(1,3)); intSet.insert(PairInt(1,4)); intSet.insert(PairInt(1,4)); intSet.insert(PairInt(4,1)); } At the moment, the (4,1) pair gets added even though there is already a (1,4) pair. The final contents of the set are: (1 3) (1 4) (4 1) and I want it to be (1 3) (1 4) I've tried putting breakpoints in the overloaded method, but they never get reached. What have I done wrong?

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• C++ Template Iterator error

  - by gprime

  I am going over some code i wrote in 2006 as an undergrad. It's a simple genetic algorithm library written in C++ using templates. It use to work in 2006 when i coded it with visual studio, but now when i am trying to run it in xcode i get compile errors. This function is giving me errors: friend bool operator==(const TSPGenome<T> & t1, const TSPGenome<T> & t2) { // loop through each interator and check to see if the two genomes have the same values if(t1.genome_vec->size() != t2.genome_vec->size()) return false; else { // iterate through each vector<T>::iterator it_t1; vector<T>::iterator it_t2; it_t1 = t1.genome_vec->begin(); for(it_t2 = t2.genome_vec->begin(); it_t2 != t2.genome_vec->end(); ++it_t2, ++it_t1) { if(*it_t2 != *it_t1) return false; } } // everything seems good return true; } xcode complains about these two lines not having ; before it_t1 and it_t2. vector<T>::iterator it_t1; vector<T>::iterator it_t2; Is it because the vector type it T? I declared it in the class as follows: template <typename T> class TSPGenome : public Genome { Any help would be appreciated. Thanks!

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• Implementing comparision operators via 'tuple' and 'tie', a good idea?

  - by Xeo

  (Note: tuple and tie can be taken from Boost or C++11.) When writing small structs with only two elements, I sometimes tend to choose a std::pair, as all important stuff is already done for that datatype, like operator< for strict-weak-ordering. The downsides though are the pretty much useless variable names. Even if I myself created that typedef, I won't remember 2 days later what first and what second exactly was, especially if they are both of the same type. This gets even worse for more than two members, as nesting pairs pretty much sucks. The other option for that is a tuple, either from Boost or C++11, but that doesn't really look any nicer and clearer. So I go back to writing the structs myself, including any needed comparision operators. Since especially the operator< can be quite cumbersome, I thought of circumventing this whole mess by just relying on the operations defined for tuple: Example of operator<, e.g. for strict-weak-ordering: bool operator<(MyStruct const& lhs, MyStruct const& rhs){ return std::tie(lhs.one_member, lhs.another, lhs.yet_more) < std::tie(rhs.one_member, rhs.another, rhs.yet_more); } (tie makes a tuple of T& references from the passed arguments.) Edit: The suggestion from @DeadMG to privately inherit from tuple isn't a bad one, but it got quite some drawbacks: If the operators are free-standing (possibly friends), I need to inherit publicly With casting, my functions / operators (operator= specifically) can be easily bypassed With the tie solution, I can leave out certain members if they don't matter for the ordering Are there any drawbacks in this implementation that I need to consider?

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• loading record into detailview

  - by summer

  please please i need help..i think i am lost somewhere..basically i followed the example http://www.iphonesdkarticles.com/2008/10/sqlite-tutorial-loading-data-as.html, but i was stuck with error on reading description..something must had gone wrong some well but i am not very sure how should i solve it. this is my code, actually i dun really have an idea on wat's really going in this code..help please..2days!! no solution!! - (void) hydrateDetailViewData { //if detail view is hydrated then do not get it from database if(isDetailViewHydrated) return; if(detailStmt == nil) { const char *sql = "select snapTitle, snapDesc from Snap where snapID =?"; if(sqlite3_prepare_v2(database, sql, -1, &detailStmt, NULL) != SQLITE_OK) NSAssert1(0, @"Error while creating detail view statement. '%s'", sqlite3_errmsg(database)); NSLog(@"SQLite= %d", sqlite3_step(detailStmt)); } if(SQLITE_DONE != sqlite3_step(detailStmt)) { // NSString *descStr = [[NSString alloc] //initWithString:sqlite3_column_text(detailStmt, 2)]; NSString *descStr = [NSString stringWithUTF8String:(char *)sqlite3_column_text(detailStmt,2)]; self.snapDescription = descStr; [descStr release]; } else NSAssert1(0, @"Error getting description of snap2play. '%s'", sqlite3_errmsg(database)); sqlite3_reset(detailStmt); isDetailViewHydrated = YES; //if hydrated, make sure do not get from database again. } }

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• Identifying memory leaks in C++

  - by Dororo

  I've got the following bit of code, which I've narrowed down to be causing a memory leak (that is, in Task Manager, the Private Working Set of memory increases with the same repeated input string). I understand the concepts of heaps and stacks for memory, as well as the general rules for avoiding memory leaks, but something somewhere is still going wrong: while(!quit){ char* thebuffer = new char[210]; //checked the function, it isn't creating the leak int size = FuncToObtainInputTextFromApp(thebuffer); //stored in thebuffer string bufferstring = thebuffer; int startlog = bufferstring.find("$"); int endlog = bufferstring.find("&"); string str_text=""; str_text = bufferstring.substr(startlog,endlog-startlog+1); String^ str_text_m = gcnew String(str_text_m.c_str()); //some work done delete str_text_m; delete [] thebuffer; } The only thing I can think of is it might be the creation of 'string str_text' since it never goes out of scope since it just reloops in the while? If so, how would I resolve that? Defining it outside the while loop wouldn't solve it since it'd also remain in scope then too. Any help would be greatly appreciated.

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• Accessing Application Scoped Bean Causes NullPointerException

  - by user2946861

  What is an Application Scoped Bean? I understand it to be a bean which will exist for the life of the application, but that doesn't appear to be the correct interpretation. I have an application which creates an application scoped bean on startup (eager=true) and then a session bean that tries to access the application scoped bean's objects (which are also application scoped). But when I try to access the application scoped bean from the session scoped bean, I get a null pointer exception. Here's excerpts from my code: Application Scoped Bean: @ManagedBean(eager=true) @ApplicationScoped public class Bean1 implements Serializable{ private static final long serialVersionUID = 12345L; protected ArrayList<App> apps; // construct apps so they are available for the session scoped bean // do time consuming stuff... // getters + setters Session Scoped Bean: @ManagedBean @SessionScoped public class Bean2 implements Serializable{ private static final long serialVersionUID = 123L; @Inject private Bean1 bean1; private ArrayList<App> apps = bean1.getApps(); // null pointer exception What appears to be happening is, Bean1 is created, does it's stuff, then is destroyed before Bean2 can access it. I was hoping using application scoped would keep Bean1 around until the container was shutdown, or the application was killed, but this doesn't appear to be the case.

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