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  • Reading from a file into an array in c

    - by NaNa21
    My file contains a series of numbers (integer, float, integer, float ....), each written on a separate line. The numbers of columns are different from one line to another i.e. 1 2.45 3 1.75 5 3.45 7 2.55 9 3.25 6 1.75 4 3.55 6 2.55 9 2.45 The program should read the contents of the entire file and place the data into an array of type float with an entry for each line. Here is my basic solution, but this is only suitable if I have fixed no of columns. float Read(FILE *pFile) { char line[50]; char letter[5]; fi = fopen("file.txt", "r"); while (fgets(line,200,fi)!=NULL) { sscanf(line,"%f %f %f",&a[i], &a2[i],&a3[i]); printf("%2.0f %2.5f %2.0f\n",a[i],a2[i],a3[i]); } fclose(fi); return a[i]; } Please HELP.

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  • how to create multiple tcp connections between server and client

    - by lowcosthighperformance
    I am new in Unix/Linux networking programming, so I have written server-client program in below.In this code there is one socket between client and server, client requests to server, then server responses from 1 to 100 numbers to client. So my question is how can we do this process with 3 socket( tcp connection) without using thread? ( e.g. First socket runs then second runs then third runs then first again .. ) Do you have any suggestion? Thank you client.c int main() { int sock; struct sockaddr_in sa; int ret; char buf[1024]; int x; sock = socket (AF_INET, SOCK_STREAM, 0); bzero (&sa, sizeof(sa)); sa.sin_family = AF_INET; sa.sin_port = htons(SERVER_PORT); inet_pton (AF_INET, SERVER_IP, &sa.sin_addr); ret = connect (sock, (const struct sockaddr *) &sa,sizeof (sa)); if (ret != 0) { printf ("connect failed\n"); exit (0); } x = 0; while (x != -1) { read (sock, buf , sizeof(int)); x = ntohl(*((int *)buf)); if (x != -1) printf ("int rcvd = %d\n", x); } close (sock); exit (0); } server.c int main() { int list_sock; int conn_sock; struct sockaddr_in sa, ca; socklen_t ca_len; char buf[1024]; int i; char ipaddrstr[IPSTRLEN]; list_sock = socket (AF_INET, SOCK_STREAM, 0); bzero (&sa, sizeof(sa)); sa.sin_family = AF_INET; sa.sin_addr.s_addr = htonl(INADDR_ANY); sa.sin_port = htons(SERVER_PORT); bind (list_sock,(struct sockaddr *) &sa,sizeof(sa)); listen (list_sock, 5); while (1){ bzero (&ca, sizeof(ca)); ca_len = sizeof(ca); // important to initialize conn_sock = accept (list_sock,(struct sockaddr *) &ca,&ca_len); printf ("connection from: ip=%s port=%d \n",inet_ntop(AF_INET, &(ca.sin_addr), ipaddrstr, IPSTRLEN),ntohs(ca.sin_port)); for (i=0; i<100; ++i){ *((int *)buf) = htonl(i+20); // we using converting to network byte order write (conn_sock, buf, sizeof(int)); } * ((int *)buf) = htonl(-1); write (conn_sock, buf, sizeof(int)); close (conn_sock); printf ("server closed connection to client\n"); } }

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  • C++ Declaring an uninitialized variable without a null constructor

    - by xbonez
    Consider the DUPoint class, whose declaration appears below. Assume this code appears in a file named DUPoint.h: #include <string> class DUPoint { public: DUPoint (int x, int y); int getX () const; int getY () const; void setX (int x); void setY (int y); void print(); private: int x_; int y_; }; Is it true that you cannot declare an uninitialized DUPoint variable with a statement such as DUPoint P; using this class as currently configured because it has no null constructor?

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  • C++ how to store integer into a binary file??

    - by blaxc
    i gt a struct with 2 integer, i want to store them in a binary file and read it again... here is my code... struct pw { int a; int b; }; void main(){ pw* p = new pw(); pw* q = new pw(); std::ofstream fout(ADMIN_FILE, ios_base::out | ios_base::binary | ios_base::trunc); std::ifstream fin(ADMIN_FILE, ios_base::in | ios_base::binary); p->a=123; p->b=321; fout.write((const char*)p, sizeof(pw)); fin.write((char*)q, sizeof(pw)); fin.close(); cout<< q->a << endl;} my output is 0. anyone can tell me what is the problem?

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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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  • 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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  • Sqlite insertion problem

    - by Devi
    Hi, I had sqlite database for my application I am able to retrieve values from my sqlite table and inserting values with no sql error but unable to find in sqlite table....please do needful help for this problem. I just stucked up at this point plz help me here is my code NSMutableString *registrationquery=[NSMutableString stringWithFormat:@"insert into tbl_kicks values ('%@','%@','%@')",[totalkicks text],[sessionstart text],[sessionstart text],@"0"]; //NSString *sqlNSString = [NSString stringWithFormat:@"INSERT INTO 'tbl_kicks' VALUES('%d','%@','%@');", // 4,sessionstart.text, appDelegate.note]; const char *sqlString = [registrationquery UTF8String]; char *sqlError; sqlite3_exec( appDelegate.database, sqlString, NULL, NULL, &sqlError );

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  • C++: Throwing shared_ptr of derived and catching shared_ptr of base?

    - by hasvn
    Ok, I've been told this problem: Why can you throw a pointer to a derived class and catch a pointer to its base... but you can't do that with shared_ptrs? Example, this works: class Base {}; class Derived : public Base {}; int main() { try { throw new Derived() ; } catch( const Base2 * b ) { printf("Received a base" ) ; } return 0 ; } But this doesn't int main() { try { throw std::tr1::shared_ptr<Derived>( new Derived() ) ; } catch( const std::tr1::shared_ptr<Base> & b ) { printf("Received a base" ) ; } return 0 ; } Any ideas?

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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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  • C# equivalent of recv?

    - by mlh
    Hello, I have a portion of C code that I am trying to port over to C#. In my C code, I create a socket and then issue a receive command. The receive command is void receive(mysocket, char * command_buffer) { recv(mysocket, command_buffer, COMMAND_BUFFER_SIZE, 0); } now, the command buffer is returned with new values including command_buffer[8] being a pointer to a string. I'm really confused as to how to do this in C# because C# Read() command specifically takes in bytes and not char. The important part is that I get the pointer to the string. Any ideas?

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  • Returning objects with dynamic memory

    - by Caulibrot
    I'm having trouble figuring out a way to return an object (declared locally within the function) which has dynamic memory attached to it. The problem is the destructor, which runs and deletes the dynamic memory when the object goes out of scope, i.e. when I return it and want to use the data in the memory that has been deleted! I'm doing this for an overloaded addition operator. I'm trying to do something like: MyObj operator+( const MyObj& x, const MyObj& y ) { MyObj z; // code to add x and y and store in dynamic memory of z return z; } My destructor is simply: MyObj::~MyObj() { delete [] ptr; } Any suggestions would be much appreciated!

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  • What's the simplest way of defining lexicographic comparison for elements of a class?

    - by the_mandrill
    If I have a class that I want to be able to sort (ie support a less-than concept), and it has several data items such that I need to do lexicographic ordering then I need something like this: struct MyData { string surname; string forename; bool operator<(const MyData& other) const { return surname < other.surname || (surname==other.surname && forename < other.forename); } }; This becomes pretty unmanageable for anything with more than 2 data members. Are there any simpler ways of achieving it? The data members may be any Comparable class.

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  • Singly-Linked Lists insert_back and isIncreasing

    - by rezivor
    I just finished writing a program that I can add, remove or print objects to a list, but I am having difficulty implementing two more functions that is insert_back, which inserts a value to the end of a list. Also,I have to modify the representation of a List and alter whatever methods are necessary to make insert_back run in constant time: O(1). This new operation should have the signature: void List::insert_back( const Object& data ); Also, isIncreasing, For example, for a list containing head-() (11) (8) (15) (3), isIncreasing() should return false. However, it would return true when working on a list containing head- () (7) (9) (15). This new operation should have the signature: bool List::isIncreasing() const; Thank you

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  • hash table with chaining method program freezing

    - by Justin Carrey
    I am implementing hash table in C using linked list chaining method. The program compiles but when inserting a string in hash table, the program freezes and gets stuck. The program is below: struct llist{ char *s; struct llist *next; }; struct llist *a[100]; void hinsert(char *str){ int strint, hashinp; strint = 0; hashinp = 0; while(*str){ strint = strint+(*str); } hashinp = (strint%100); if(a[hashinp] == NULL){ struct llist *node; node = (struct llist *)malloc(sizeof(struct llist)); node->s = str; node->next = NULL; a[hashinp] = node; } else{ struct llist *node, *ptr; node = (struct llist *)malloc(sizeof(struct llist)); node->s = str; node->next = NULL; ptr = a[hashinp]; while(ptr->next != NULL){ ptr = ptr->next; } ptr->next = node; } } void hsearch(char *strsrch){ int strint1, hashinp1; strint1 = 0; hashinp1 = 0; while(*strsrch){ strint1 = strint1+(*strsrch); } hashinp1 = (strint1%100); struct llist *ptr1; ptr1 = a[hashinp1]; while(ptr1 != NULL){ if(ptr1->s == strsrch){ cout << "Element Found\n"; break; } else{ ptr1 = ptr1->next; } } if(ptr1 == NULL){ cout << "Element Not Found\n"; } } hinsert() is to insert elements into hash and hsearch is to search an element in the hash. Hash function is written inside hinsert() itself. In the main(), what i am initializing all the elements in a[] to be NULL like this: for(int i = 0;i < 100; i++){ a[i] = NULL; } Help is very much appreciated. Thanks !

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  • extracting string occurrence in c

    - by David78
    I have a string from a text file that look something like this: long_str = "returns between paragraphs 20102/34.23" - 9203 1232 "test" "basic HTML" Note: Quotes are part of the string. int match(char *long_str){ char * str; if ((str = strchr(long_str, '"')) != NULL) str++; // last " ? else return 1; return 0; } Using strstr I'm trying to get the whole substring between the last two quotes: "basic HTML". I'm just not quite sure what would be a good and efficient way of getting that match. I'm open to any other ideas on how to approach this. Thanks

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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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  • Change Wallpaper in windows mobile

    - by niks86
    Hello Friends, Hey im devloping application in that i want to set images as the wallpaper for that i written below code.when i used remote registry in registry value get updated but the wallpaper of the windows mobile does not changed.Can u plz tel me what i need to do. Here is my code. [DllImport("coredll.dll")] private static extern int SendMessage(IntPtr hWnd, uint msg, int wParam, int lParam); public const int HWND_BROADCAST = 0xffff; public const int WM_WININICHANGE = 0x001A; File.Copy(@"\My Documents\My Pictures\Album Sample_05.jpg", @"\My Documents\My Pictures\Album Sample_09.jpg", true); Registry.SetValue(@"HKEY_CURRENT_USER\Software\Microsoft\Today", "Wall", @"\My Documents\My Pictures\Album Sample_05.jpg"); SendMessage((IntPtr)HWND_BROADCAST, WM_WININICHANGE, 0xF2, 0); plz help me. Thanks.

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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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  • Getting MATLAB variable (string) from C

    - by Hamming
    Hi! I'm writing a small C application that launchs a Matlab script (.m file). I need to exchange some variables and I don't know how to get an array of chars that exists in Matlab. I'm doing something like this: enter code here result = engGetVariable(ep,"X"); if (!result) { printf ("Error..."); exit -1; } int n = mxGetN(result); char *varx = NULL; memcpy(varx, mxGetData(result),n*sizeof(char)); It doesn't work. Does someone know how to get a Matlab string in C? I've read Matlab documentation about engGetVariable() and the provided example but any of this things clarify me.

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  • Writing a C++ wrapper for a C library

    - by stripes
    I have a legacy C library, written in an OO type form. Typical functions are like: LIB *lib_new(); void lib_free(LIB *lib); int lib_add_option(LIB *lib, int flags); void lib_change_name(LIB *lib, char *name); I'd like to use this library in my C++ program, so I'm thinking a C++ wrapper is required. The above would all seem to map to something like: class LIB { public: LIB(); ~LIB(); int add_option(int flags); void change_name(char *name); ... }; I've never written a C++ wrapper round C before, and can't find much advice about it. Is this a good/typical/sensible approach to creating a C++/C wrapper?

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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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  • Redundant naming in C/C++ typedefs/structs

    - by bloomy
    #include <stdio.h> #include <string.h> const int NAMELEN=30; const int MAXCLASSSIZE=10; typedef struct StudentRec { char lastname[NAMELEN]; char firstname[NAMELEN]; long int ID; int finalmark; }Student; I'm new to coding..and I have a question about why there is Student; after the bracket.. is it a format that we have to follow.

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  • How to split the definition of template friend funtion within template class?

    - by ~joke
    The following example compiles fine but I can't figure out how to separate declaration and definition of operator<<() is this particular case. Every time I try to split the definition friend is causing trouble and gcc complains the operator<<() definition must take exactly one argument. #include <iostream> template <typename T> class Test { public: Test(const T& value) : value_(value) {} template <typename STREAM> friend STREAM& operator<<(STREAM& os, const Test<T>& rhs) { os << rhs.value_; return os; } private: T value_; }; int main() { std::cout << Test<int>(5) << std::endl; }

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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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