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  • Visual C++ CreateThread Parameter Problem

    - by Vanwaril
    I have a class that contains a function that calls create thread, and needs to pass itself (this) as a parameter: DWORD threadId; HANDLE h = CreateThread( NULL, 0, runThread, this, 0, &threadId); My runThread definition is as follows: DWORD WINAPI runThread(LPVOID args) { Obj *t = (Obj*)args; t->funct(); return 0; } Unfortunately, the object t that I get in runThread() gets garbage. My Obj class has a function pointer attribute. Could that be the problem? class Obj{ void(*funct)(); and in the constructor: Obj(void(*f)()) { funct = f; } where is my mistake? The function pointer, the createThread itself, or type-casting? I tried whatever I could think of.

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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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  • Encryption By Certificate

    - by user1817240
    I am encrypting customer name in database at database level. While saving in database only first letter of customer name is saved and hence while decrypting only first letter is retrieved. The following code shows the test sp. ALTER PROCEDURE [dbo].[spc_test_insert] ( @sFIRST_NAME typ_encryptedtext, ) AS BEGIN DECLARE @sSENCRYPTION_KEY char(15) DECLARE @sCERTIFICATE char(22) SET @sSENCRYPTION_KEY='SymmetricKey1' SET @sCERTIFICATE='CustomerCertificate' OPEN SYMMETRIC KEY SymmetricKey1 DECRYPTION BY CERTIFICATE CustomerCertificate; INSERT INTO test_table ( FIRST_NAME, ) Values ( -- Add the Params to be Added... EncryptByKey(Key_GUID(@sSENCRYPTION_KEY),@sFIRST_NAME), ) CLOSE SYMMETRIC KEY SymmetricKey1 END encryption decryption working fine in normal insert but its not working in stored procedure.

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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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  • Removing Unused (Unreferenced) Static Global Variable Constants in C++

    - by Synetech inc.
    Hi, I have a header file with a few common constants like names and stuff that are automatically included in each project (an example follows). The thing is that they are included in the compiled binary (EXE) whether they are used (referenced) or not. If I use DEFINEs instead, then naturally they are not included if they are not used, but of course consts are better than defines so… I tried Googling it, but the closest thing I could find was a question right here on SO that did not quite help. Matters of i18n aside, how can I keep the ones that are not used out of the binary, while still keeping it easy to use like this? Thanks. //COMMON.H: static const CString s_Company _T("Acme inc."); //etc. static const CString s_Digits _T("0123456789"); //TEST.CPP: #include common.h int main() { AfxMessageBox(s_Company); } //s_Company should be in the final EXE, but s_Digits should not be, but is

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  • C++: Could Polymorphic Copy Constructors work?

    - by 0xC0DEFACE
    Consider: class A { public: A( int val ) : m_ValA( val ) {} A( const A& rhs ) {} int m_ValA; }; class B : public A { public: B( int val4A, int val4B ) : A( val4A ), m_ValB( val4B ) {} B( const B& rhs ) : A( rhs ), m_ValB( rhs.m_ValB ) {} int m_ValB; }; int main() { A* b1 = new B( 1, 2 ); A* b2 = new A( *b1 ); // ERROR...but what if it could work? return 0; } Would C++ be broken if "new A( b1 )" was able to resolve to creating a new B copy and returning an A? Would this even be useful?

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  • Debugging metaprograms [C++]

    - by atch
    Hi, Is there any way to check step by step what's going on in let's say template? I mean how it is instantiated step by step and so on? In book I've mentioned here , I found (2 minutes ago) quite interesting example of how binary could be implemented as a metafunction. template <unsigned long N> struct binary { static unsigned const value = binary<N/10>::value << 1 // prepend higher bits | N%10; // to lowest bit }; template <> // specialization struct binary<0> // terminates recursion { static unsigned const value = 0; }; and I think it could be quite useful to be able to see step by step what's been done during the instantiation of this template. Thanks for your replies.

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  • C++ convert formatted string to a stream

    - by Roey
    Hi All, I'm using VS2008 C++. As I understand it there is no way to pass something like this in a C++ stream : (without using external libraries) "number " << i <------ when i is an integer. So I was looking for a better way to do this, and I all I could come up with is create a string using : char fullstring = new char[10]; sprintf(fullString, "number %d", i); .... pass fullstring to the stream ..... delete[] fullString; I know it's stupid, but is there a better way of doing this?

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  • array of objects of a class

    - by anurag18294
    #include class test{ int a; char b; public: test() { cout<<"\n\nDefault constructor being called"; } test(int i,char j) { a=i; b=j; cout<<"\n\nConstructor with arguments called"; } }; int main() { test tarray[5]; test newobj(31,'z'); }; In the above code snippet can we intialize values to tarray[5].

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  • Getting the fractional part of a float without using modf()

    - by knight666
    Hi, I'm developing for a platform without a math library, so I need to build my own tools. My current way of getting the fraction is to convert the float to fixed point (multiply with (float)0xFFFF, cast to int), get only the lower part (mask with 0xFFFF) and convert it back to a float again. However, the imprecision is killing me. I'm using my Frac() and InvFrac() functions to draw an anti-aliased line. Using modf I get a perfectly smooth line. With my own method pixels start jumping around due to precision loss. This is my code: const float fp_amount = (float)(0xFFFF); const float fp_amount_inv = 1.f / fp_amount; inline float Frac(float a_X) { return ((int)(a_X * fp_amount) & 0xFFFF) * fp_amount_inv; } inline float Frac(float a_X) { return (0xFFFF - (int)(a_X * fp_amount) & 0xFFFF) * fp_amount_inv; } Thanks in advance!

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  • Program quits if pipe is closed

    - by givemelight
    I am trying to write to a pipe using C++. The following code gets called in an extra thread: void writeToPipe() { int outfifo; char buf[100]; char outfile[] = "out"; mknod(outfile, S_IFIFO | 0666, 0); if ((outfifo = open(outfile, O_WRONLY)) < 0) { perror("Opening output fifo failed"); return false; } int currentTimestamp = (int)time(0); int bufLen = sprintf(bug, "Time is %d.", currentTimestamp); write(outfifo, buf, bufLen); } The thread is called in main using: thread writeThread(writeToPipe); writeThread.detach(); If the pipe is not opened by another process, the C++ program just quits without an error. I don't know how to check if the pipe is opened.

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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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  • I was making this program and the server wont send to the client

    - by crstin
    void CApplication::SendData( const char pBuffer[] ) { if( pBuffer == NULL ) { Log()->Write( ELogMessageType_ERROR, "Cannot send NULL message."); return; } // calculate the size of that data unsigned long messageSize = strlen( pBuffer ); // fix our byte ordering messageSize = htonl( messageSize ); if( isServer == true ) { for( unsigned int i = ESocket_CLIENT0; i < ESocket_MAX; ++i ) { // send the message size if( m_Socket[ i ] > 0 ) { if( send( m_Socket[ i ], (char*)&messageSize, sizeof( messageSize ), 0 ) == SOCKET_ERROR ) { Log()->Write( ELogMessageType_ERROR, "[Application] Send error: %i to socket %i", WSAGetLastError(), m_Socket[ i ] ); continue; } // fix our message size back to host ordering messageSize = ntohl(messageSize); // send the actual message if( send( m_Socket[ i ], pBuffer, messageSize, 0 ) == SOCKET_ERROR ) { Log()->Write( ELogMessageType_ERROR, "[Application] Send error: %i to socket %i", WSAGetLastError(), m_Socket[ i ] ); continue; } Log()->Write( ELogMessageType_MESSAGE, "[Application] SEND: %s", pBuffer ); } } }

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  • Adding characters to string

    - by Jamza
    I am currently trying to build a very basic serial shell with my arduino. I am able to get an output from the device using Serial.read() and can get the character it has outputted, but I cannot work out how to then add that character to a longer to form the full command. I tried the logical thing but it doesn't work: char Command[]; void loop(){ if(Serial.available() > 0){ int clinput = Serial.read(); Command = Command + char(clinput); } Can anybody help? Thank You.

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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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  • why does it use the movl instead of push ?!

    - by user554403
    hi all. pay attention to this code : #include <stdio.h> void a(int a, int b, int c) { char buffer1[5]; char buffer2[10]; } int main() { a(1,2,3); } after that : gcc -S a.c that command shows our source code in assembly. now we can see in the main function, we never use "push" command to push the arguments of the a function into the stack. and it used "movel" instead of that main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $16, %esp movl $3, 8(%esp) movl $2, 4(%esp) movl $1, (%esp) call a leave why does it happen? what's difference between them?

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  • C++: Checking for non-numeric input and assigning to a double

    - by Brundle
    Here is the code I have at the moment: char ch; int sum = 0; double values[10]; int i = 0; cin >> ch; while (!isalpha(ch)) { values[i] = ch; sum += values[i]; i++; cin >> ch; } What is happening is that if I enter the value 1, that gets assigned to ch as a char. Now ch is assigning it's value to a double and doing an implicit cast. So it is assigning the ASCII value of '1' to values[i]. I want it to just assign 1 to values[i]. Is there a better way to do this? Or is there something that I'm missing?

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  • Abstract class and operator!= in c++

    - by Alessandro Teruzzi
    Hi All, I have problem implementing the operator!= in a set class deriving from an abstact one. The code looks like this: class Abstract { public: //to make the syntax easier let's use a raw pointer virtual bool operator!=(const Abstract* other) = 0; }; class Implementation { SomeObject impl_; //that already implement the operator!= public: bool operator!=(const Abstract* other) { return dynamic_cast<Implementation*>(other)->impl_ != this->impl_; } }; This code works but it has the drawback to use dynamic_cast and I need to handle error in casting operation. This is a generic problem that occur when a function of a concrete class it is trying to using some internal information (not available at the abstract class level) to perform a task. Is there any better way to solve this kind of problem? Cheers

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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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  • use printf("text %d", number) type format to assign value to variable

    - by rksprst
    I would like to use the syntax that printf uses, using the %d, %s and adding values after to assign a value to a char[]. Is this possible? e.g. Given an output of: printf("now: %d-%d-%d %d:%d:%d\n", tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec); I'd like to assign that to char[] output; How can this be done? I tried: sprintf(output, "now: %d-%d-%d %d:%d:%d\n", tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec); but that didn't seem to work. Is sprintf used differently... or is that not what I should be using? Thanks!

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  • MySql query and table optimisation

    - by Cheeky
    Hi everyone. I am trying to run the following simple query on a table with 500K records. SELECT COUNT(*) AS impressionCount FROM impression WHERE 0 = 0 AND impressionObjectId1 = 'C69A54B8-B828-E2E4-2319A93011DF4120' AND impressionObjectId2 = '1'; This query is taking 10 seconds to run. I have tried creating individual indexes for the impressionObjectId1 and impressionObjectId2 columns, as well as a composite index using both. The composite worked well for a while, but now it is also slow. Here is my table structure: DROP TABLE IF EXISTS `impression`; CREATE TABLE `impression` ( `impressionId` varchar(50) NOT NULL, `impressionObjectId1` varchar(50) NOT NULL, `impressionObjectId2` varchar(50) default NULL, `impressionStampDate` datetime NOT NULL, PRIMARY KEY (`impressionId`), KEY `IX_object` (`impressionObjectId1`,`impressionObjectId2`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 ROW_FORMAT=DYNAMIC COMMENT='InnoDB free: 191488 kB'; Any advice would be greatly appreciated. Thanks EDIT: When adding an EXPLAIN, this is the output: 1, 'SIMPLE', 'impression', 'ref', 'IX_object', 'IX_object', '105', 'const,const', 304499, 'Using where; Using index'

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  • Is this a valid C statement ?

    - by Philando Gullible
    Lets say I write char c[99] = {'Stack Overflow'}; in C or C++ it does compiles fine but does this valid? By valid I meant not invoking any kind of undefined or unspecified behavior. Again if I write char c[99] = 'Stack Overflow'; gcc complains about multicharacter constant which is obvious but in the above when I am enclosing within curly brackets compiler is happy! why is it so ? I also notice that puts(c); after the first statement will output 'w' precisely the last character of a general string in-place of Stack Overflow. why so ? Could somebody explain this behavior may be separately.

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  • including a std::map within a struct? Is it ok?

    - by user553514
    class X_class{ public: struct extra {int extra1; int extra2; int extra3; }; enum a { n,m}; struct x_struct{ char b; char c; int d; int e; std::map <int, extra> myExtraMap; }; }; in my code I define : x_struct myStruct; why do I get compile errors compiling the above class? The error either says: 1) expected ; before < on the line --- where I defined the map (above) if I eliminate std:: or 2) error: invalid use of ::; error: expected ; before < token

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  • What is wrong with my loop?

    - by user3966541
    I have the following loop and don't understand why it only runs once: std::vector<sf::RectangleShape> shapes; const int res_width = 640; const int res_height = 480; for (int x = 0; x < res_width / 50; x += 50) { for (int y = 0; y < res_height / 50; y += 50) { sf::RectangleShape shape(sf::Vector2f(50, 50)); shape.setPosition(x * 50, y * 50); sf::Color color = (x % 2 == 0) ? sf::Color::Green : sf::Color::Red; shape.setFillColor(sf::Color::Green); shapes.push_back(shape); } }

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  • How to efficiently render different things at different times in a game?

    - by Baqjohanson
    Sorry for the ambiguous title. What I am wondering is what is an efficient way to alternate rendering between lets say a main menu, options menu, and "in the game." The only two ways I've come up with so far are to have 1 render function, with code for each part (menu, ...) and a variable to control what gets drawn, or to have multiple render functions, and use a function pointer to point to the appropriate one, and then just call the function pointer. I always wonder how more professional games do it.

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