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  • PHP , What is the difference between fopen r+ and r ! does it matter if i used r+ when not intending

    - by Naughty.Coder
    when I use fopen function , why don't I use r+ always , even when I'm not going to write any thing ... is there a reason for separating writing/reading process from only reading .. like , the file is locked for reading when I use r+ , because i might write new data into it or something ... another question : in php manual a+ : Open for reading and writing; place the file pointer at the end of the file. If the file does not exist, attempt to create it. What is supposed to be read if you are at the end of the file ..(pointer at the end) !!? where to learn more about the filesystem thing .... it's confusing

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  • Set intersection of two strings

    - by user1785712
    import java.util.*; class set { public static void main(String args[]) { TreeSet<Character> t1 = new TreeSet<Character>(); TreeSet<Character> t2 = new TreeSet<Character>(); String s1 = "Ambitab bachan"; String s2 = "Ranjikanth"; for(char c1:s1.toCharArray()) t1.add(c1); for(char c2:s2.toCharArray()) t2.add(c2); t2.retainAll(t1); System.out.println(t2); } } this program find the common character in two different string. in this program Treeset is used to store the value and retainAll() method is used to find the common characters. can anybody help me reduce the line of coding.thanks in advance

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  • Copy unmanaged data into managed array

    - by JeffRSon
    I need to copy native (i.e. unmanaged) data (byte*) to managed byte array with C++/CLI (array). I tried Marshal::Copy (data is pointed to by const void* data and is dataSize bytes) array<byte>^ _Data=gcnew array<byte>(dataSize); System::Runtime::InteropServices::Marshal::Copy((byte*)data, _Data, 0, dataSize); This gives error C2665: none of the 16 overloads can convert all parameters. Then I tried System::Runtime::InteropServices::Marshal::Copy(new IntPtr(data), _Data, 0, dataSize); which produces error C2664: parameter 1 cannot be converted from "const void*" to "__w64 int". So how can it be done and is Marshal::Copy indeed the "best" (simplest/fastest) way to do so?

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  • Comparing structs in C++

    - by kamziro
    So in C++ There's a lot of times where you need to make an "index" class. For example: class GameID{ public: string name; int regionid; int gameid; bool operator<(const GameID& rhs) const; } Now, if we were to represent GameID as pair , the operator comparison just comes with it. Is there any other way to get that automatic operator comparison without having to use std::pair< ?

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  • Any idea why this query always returns duplicate items?

    - by Kardo
    I want to get all Images not used by current ItemID. The this subquery but it also always returns duplicate Images: EDITED select Images.ImageID, Images.ItemStatus, Images.UserName, Images.Url, Image_Item.ItemID, Image_Item.ItemID from Images left join (select ImageID, ItemID, MAX(DateCreated) x from Image_Item where ItemID != '5a0077fe-cf86-434d-9f3b-7ff3030a1b6e' group by ImageID, ItemID having count(*) = 1) image_item on Images.imageid = image_item.imageid where ItemID is not null I guess the problem is with the subquery which I can't avoid duplicate rows: select ImageID, ItemID, MAX(DateCreated) x from Image_Item where ItemID != '5a0077fe-cf86-434d-9f3b-7ff3030a1b6e' group by ImageID, ItemID having count(*) = 1 Result: F2EECBDC-963D-42A7-90B1-4F82F89A64C7 0578AC61-3C32-4A1D-812C-60A09A661E71 F2EECBDC-963D-42A7-90B1-4F82F89A64C7 9A4EC913-5AD6-4F9E-AF6D-CF4455D81C10 42BC8B1A-7430-4915-9CDA-C907CBC76D6A CB298EB9-A105-4797-985E-A370013B684F 16371C34-B861-477C-9A7C-DEB27C8F333D 44E6349B-7EBF-4C7E-B3B0-1C6E2F19992C Table: Images ImageID uniqueidentifier UserName nvarchar(100) DateCreated smalldatetime Url nvarchar(250) ItemStatus char(1) Table: Image_Item ImageID uniqueidentifier ItemID uniqueidentifier UserName nvarchar(100) ItemStatus char(1) DateCreated smalldatetime Any kind help is highly appreciated.

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  • reading unicode

    - by user121196
    I'm using java io to retrieve text from a server that might output character such as é. then output it using System.err, they turn out to be '?'. I am using UTF8 encoding. what's wrong? int len=0; char[]buffer=new char[1024]; OutputStream os = sock.getOutputStream(); InputStream is = sock.getInputStream(); os.write(query.getBytes("UTF8"));//iso8859_1")); Reader reader = new InputStreamReader(is, Charset.forName("UTF-8")); do{ len = reader.read(buffer); if (len0) { if(outstring==null)outstring=new StringBuffer(); outstring.append(buffer,0,len); } }while(len0); System.err.println(outstring);

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  • C++: use array of strings wrapped in namespace?

    - by John D.
    I got the following code, wishing to wrap a group of strings nicely in a namespace: namespace msgs { const int arr_sz = 3; const char *msg[arr_sz] = {"blank", "blank", "blank" }; msg[0] = "Welcome, lets start by getting a little info from you!\n"; msg[1] = "Alright, bla bla bla.."; msg[2] = "etc."; } The code inside works nicely inside a function, but I don't know how to return an array from it. The namespace idea LOOKS fine, but it returns on the last three lines: error: expected constructor, destructor, or type conversion before ‘=’ token Why can't I define the array inside a namespace, do I need to do something first? It's nice because I can call it like printf(msgs::msg[1]) etc. I want to do this I just can't wrap my head around what's wrong :(

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  • What is the result of "new int[ 0 ]"? [closed]

    - by ArunSaha
    Possible Duplicates: What does zero-sized array allocation do/mean? C++ new int[0] — will it allocate memory? int * p; p = new int[ 0 ]; What is the expected outcome when new is called for zero number of elements? Is the outcome defined or undefined? Further, is it okay to call delete [] p; on that pointer? What is the intuition/analogy to this situation of pointer to an array of zero elements? Thanks in advance. Regards, Arun

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  • does overload operator-> a compile time action?

    - by Brent
    when I tried to compile the code: struct S { void func2() {} }; class O { public: inline S* operator->() const; private: S* ses; }; inline S* O::operator->() const { return ses; } int main() { O object; object->func(); return 0; } there is a compile error reported: D:\code>g++ operatorp.cpp -S -o operatorp.exe operatorp.cpp: In function `int main()': operatorp.cpp:27: error: 'struct S' has no member named 'func' it seems that invoke the overloaded function of "operator-" is done during compile time? I'd add "-S" option for compile only.

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  • Exception in C#

    - by user1803513
    I am facing null pointer exception in below code as it is happening very rarely and I tried to debug to replicate the issue but no luck. Can anybody help me what can cause null point exception here. private static void MyTaskCompletedCallback(IAsyncResult res) { var worker = (AsyncErrorDelegate)((AsyncResult)res).AsyncDelegate; var async = (AsyncOperation)asyncResult.AsyncState; worker.EndInvoke(res); lock (IsAsyncOpOccuring) { IsBusy = false; } var completedArgs = new AsyncCompletedEventArgs(null, false, null); async.PostOperationCompleted(e => OnTaskCompleted((AsyncCompletedEventArgs)e), completedArgs); } Null Pointer exception is reported at var async = (AsyncOperation)asyncResult.AsyncState;

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  • C++ Memory allocation question involving vectors

    - by TheFuzz
    vector< int > vect; int *int_ptr = new int(10); vect.push_back( *int_ptr ); I under stand that every "new" needs to be followed by a "delete" at some point but does the clear() method clean this memory? What about this method of doing the same thing: vector< int > vect; int int_var = 10; vect.push_back( int_var ); From what I understand, clear() calls the variables destructors, but both vect.push_back() methods in this example push an object on the vector, not a pointer. so does the first example using an int pointer need something other than clear() to clean up memory?

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  • Using sizeof with a dynamically allocated array

    - by robUK
    Hello, gcc 4.4.1 c89 I have the following code snippet: #include <stdlib.h> #include <stdio.h> char *buffer = malloc(10240); /* Check for memory error */ if(!buffer) { fprintf(stderr, "Memory error\n"); return 1; } printf("sizeof(buffer) [ %d ]\n", sizeof(buffer)); However, the sizeof(buffer) always prints 4. I know that a char* is only 4 bytes. However, I have allocated the memory for 10kb. So shouldn't the size be 10240? I am wondering am I thinking right here? Many thanks for any suggestions,

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  • How to implement copy operator for such C++ structure?

    - by Kabumbus
    So having struct ResultStructure { ResultStructure(const ResultStructure& other) { // copy code in here ? using memcpy ? how??? } ResultStructure& operator=(const ResultStructure& other) { if (this != &other) { // copy code in here ? } return *this } int length; char* ptr; }; How to implement copy? (sorry - I am C++ nube)

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  • Problem with Initializing Consts

    - by UdiM
    This code, when compiled in xlC 8.0 (on AIX 6.1), produces the wrong result. It should print 12345, but instead prints 804399880. Removing the const in front of result makes the code work correctly. Where is the bug? #include <stdio.h> #include <stdlib.h> #include <string> long int foo(std::string input) { return strtol(input.c_str(), NULL, 0); } void bar() { const long int result = foo("12345"); printf("%u\n", result); } int main() { bar(); return 0; } Compilation command: /usr/vacpp/bin/xlC example.cpp -g

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  • Sort an array via x86 Assembly (embedded in C++)?? Possible??

    - by Mark V.
    I am playing around with x86 assembly for the first time and I can't figure out how to sort an array (via insertion sort).. I understand the algorithm, but assembly is confusing me as I primarily use Java & C++. Heres all I have so far int ascending_sort( char arrayOfLetters[], int arraySize ) { char temp; __asm{ push eax push ebx push ecx push edx push esi push edi //// ??? pop edi pop esi pop edx pop ecx pop ebx pop eax } } Basically nothing :( Any ideas?? Thanks in advance.

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  • Objective-C: how to splt a string constant across multiple lines

    - by Ilya
    Hi, I have a pretty long sqlite query: const char *sql_query = "SELECT statuses.word_id FROM lang1_words, statuses WHERE statuses.word_id = lang1_words.word_id ORDER BY lang1_words.word ASC"; How can I break it in a number of lines to make it easier to read? If I do the following: const char *sql_query = "SELECT word_id FROM table1, table2 WHERE table2.word_id = table1.word_id ORDER BY table1.word ASC"; I am getting a error. Is there a way to write queries in multiple lines? Thank you.

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  • mysql++ compile error

    - by rizzo0917
    when i complie code that includes mysql headers i get the following errors: c:\qt\2010.03\mingw\bin../lib/gcc/mingw32/4.4.0/../../../../include/stdint.h:27: error: 'int8_t' has a previous declaration as 'typedef signed char int8_t' c:\qt\2010.03\mingw\bin../lib/gcc/mingw32/4.4.0/../../../../include/stdint.h:31: error: 'int32_t' has a previous declaration as 'typedef int int32_t' c:\qt\2010.03\mingw\bin../lib/gcc/mingw32/4.4.0/../../../../include/stdint.h:32: error: 'uint32_t' has a previous declaration as 'typedef unsigned int uint32_t' Literally all I do is this. include cppconn/driver.h include cppconn/exception.h include cppconn/resultset.h include cppconn/statement.h include Now I can go into the file and comment the lines out that give me errors //typedef signed char int8_t; //typedef int int32_t; //typedef unsigned uint32_t; It compiles, but when I try to run the mysql code: sql::Driver *driver; driver = get_driver_instance(); I get this output test.exe exited with code -1073741515 Any Ideas?

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  • Why use C typedefs rather than #defines?

    - by me_and
    What advantage (if any) is there to using typedef in place of #define in C code? As an example, is there any advantage to using typedef unsigned char UBYTE over #define UBYTE unsigned char when both can be used as void func() { UBYTE byte_value = 0; /* Do some stuff */ return byte_value; } Obviously the pre-processor will try to expand a #define wherever it sees one, which wouldn't happen with a typedef, but that doesn't seem to me to be any particular advantage or disadvantage; I can't think of a situation where either use wouldn't result in a build error if there was a problem.

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  • c++ template function compiles in header but not implementation

    - by flies
    I'm trying to learn templates and I've run into this confounding error. I'm declaring some functions in a header file and I want to make a separate implementation file where the functions will be defined. Here's the code that calls the header (dum.cpp): #include <iostream> #include <vector> #include <string> #include "dumper2.h" int main() { std::vector<int> v; for (int i=0; i<10; i++) { v.push_back(i); } test(); std::string s = ", "; dumpVector(v,s); } now, here's a working header file (dumper2.h): #include <iostream> #include <string> #include <vector> void test(); template <class T> void dumpVector( std::vector<T> v,std::string sep); template <class T> void dumpVector(std::vector<T> v, std::string sep) { typename std::vector<T>::iterator vi; vi = v.begin(); std::cout << *vi; vi++; for (;vi<v.end();vi++) { std::cout << sep << *vi ; } std::cout << "\n"; return; } with implentation (dumper2.cpp): #include <iostream> #include "dumper2.h" void test() { std::cout << "!olleh dlrow\n"; } the weird thing is that if I move the code that defines dumpVector from the .h to the .cpp file, I get the following error: g++ -c dumper2.cpp -Wall -Wno-deprecated g++ dum.cpp -o dum dumper2.o -Wall -Wno-deprecated /tmp/ccKD2e3G.o: In function `main': dum.cpp:(.text+0xce): undefined reference to `void dumpVector<int>(std::vector<int, std::allocator<int> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> >)' collect2: ld returned 1 exit status make: *** [dum] Error 1 So why does it work one way and not the other? Clearly the compiler can find test(), so why can't it find dumpVector?

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  • zeroing out memory

    - by robUK
    Hello, gcc 4.4.4 c89 I am just wondering what most c programmers do when they want to zero out memory. For example I have a buffer of 1024 bytes. Sometimes I do this: char buffer[1024] = {0}; Which will zero all bytes. However, should I declare like this and use memset? char buffer[1024]; . . memset(buffer, 0, sizeof(buffer); Is there any real reason you have to zero the memory? What is the worst that can happen by not doing it? Many thanks for any suggestions,

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  • syntax error : missing ';' before identifier

    - by numerical25
    I am new to c++, trying to debug the following line of code class cGameError { string m_errorText; public: cGameError( char *errorText ) { DP1("***\n*** [ERROR] cGameError thrown! text: [%s]\n***\n", errorText ); m_errorText = string( errorText ); } const char *GetText() { return m_errorText.c_str(); } }; enum eResult { resAllGood = 0, // function passed with flying colors resFalse = 1, // function worked and returns 'false' resFailed = –1, // function failed miserably resNotImpl = –2, // function has not been implemented resForceDWord = 0x7FFFFFFF }; This header file is included in the program as followed #include "string.h" #include "stdafx.h" #include "Chapter 01 MyVersion.h" #include "cGameError.h"

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  • c++ fread changing fgetpos strangely

    - by Steve
    If I run: FILE* pFile = fopen("c:\\08.bin", "r"); fpos_t pos; char buf[5000]; int ret = fread(&buf, 1, 9, pFile); fgetpos(pFile, &pos); I get ret = 9 and pos = 9. However if I run FILE* pFile = fopen("c:\\08.bin", "r"); fpos_t pos; char buf[5000]; int ret = fread(&buf, 1, 10, pFile); fgetpos(pFile, &pos); ret = 10 as expected, but pos = 11! How can this be?

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  • How to access constant defined in child class from parent class functions?

    - by kavoir.com
    I saw this example from php.net: <?php class MyClass { const MY_CONST = "yonder"; public function __construct() { $c = get_class( $this ); echo $c::MY_CONST; } } class ChildClass extends MyClass { const MY_CONST = "bar"; } $x = new ChildClass(); // prints 'bar' $y = new MyClass(); // prints 'yonder' ?> But $c::MY_CONST is only recognized in version 5.3.0 or later. The class I'm writing may be distributed a lot. Basically, I have defined a constant in ChildClass and one of the functions in MyClass (father class) needs to use the constant. Any idea?

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  • c++: truth assignment warning with arguments?

    - by John
    I use the following to work with arguments in my programs, but it seems to just hand me a warning (just a warning): "warning: suggest parentheses around assignment used as truth value" The beginning of the code is as follows: enum{OPT_DISP_H = 0x2, OPT_DISP_W = 0x1}; int main(int argc, char *argv[]) { int opt = 0x00; char c; while((++argv)[0] && argv[0][0]=='-'){ while(c =* ++argv[0]) switch(c){ case 'h': opt |= OPT_DISP_H; break; //etc.. The while(c =* ++argv[0]) part being where the warning persists. The code works fine, but what does this warning mean opposed to what is used? I think the code is c = *++argv[0], using the pointer. So why does the single = work and what is really recommended to be used?

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  • Second query to SQLite (on iPhone) errors.

    - by Luke
    Hi all, On the iPhone, I am developing a class for a cart that connects directly to a database. To view the cart, all items can be pulled from the database, however, it seems that removing them doesn't work. It is surprising to me because the error occurs during connection to the database, except not the second time I connect even after the DB has been closed. #import "CartDB.h" #import "CartItem.h" @implementation CartDB @synthesize database, databasePath; - (NSMutableArray *) getAllItems { NSMutableArray *items = [[NSMutableArray alloc] init]; if([self openDatabase]) { const char *sqlStatement = "SELECT * FROM items;"; sqlite3_stmt *compiledStatement; if(sqlite3_prepare_v2(cartDatabase, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) { while(sqlite3_step(compiledStatement) == SQLITE_ROW) { int rowId = sqlite3_column_int(compiledStatement, 0); int productId = sqlite3_column_int(compiledStatement, 1); NSString *features = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 2)]; int quantity = sqlite3_column_int(compiledStatement, 3); CartItem *cartItem = [[CartItem alloc] initWithRowId:rowId productId:productId features:features quantity:quantity]; [items addObject:cartItem]; [cartItem release]; } } sqlite3_finalize(compiledStatement); } [self closeDatabase]; return items; } - (BOOL) removeCartItem:(CartItem *)item { sqlite3_stmt *deleteStatement; [self openDatabase]; const char *sql = "DELETE FROM items WHERE id = ?"; if(sqlite3_prepare_v2(cartDatabase, sql, -1, &deleteStatement, NULL) != SQLITE_OK) { return NO; } sqlite3_bind_int(deleteStatement, 1, item.rowId); if(SQLITE_DONE != sqlite3_step(deleteStatement)) { sqlite3_reset(deleteStatement); [self closeDatabase]; return NO; } else { sqlite3_reset(deleteStatement); [self closeDatabase]; return YES; } } - (BOOL) openDatabase { if(sqlite3_open([databasePath UTF8String], &cartDatabase) == SQLITE_OK) { return YES; } else { return NO; } } - (void) closeDatabase { sqlite3_close(cartDatabase); } The error occurs on the line where the connection is opened in openDatabase. Any ideas? Need to flush something? Something gets autoreleased? I really can't figure it out. --Edit-- The error that I receive is GDB: Program received signal "EXC_BAD_ACCESS". --Edit-- I ended up just connecting in the init and closing in the free methods, which might not be the proper way, but that's another question altogether so it's effectively persistent instead of connecting multiple times. Still would be nice to know what was up with this for future reference.

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