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• I am not able to kill a child process using TerminateProcess

  - by user1681210

  I have a problem to kill a child process using TerminateProcess. I call to this function and the process still there (in the Task Manager) This piece of code is called many times launching the same program.exe many times and these process are there in the task manager which i think is not good. sorry, I am quiet new in c++ I will really appreciate any help. thanks a lot!! the code is the following: STARTUPINFO childProcStartupInfo; memset( &childProcStartupInfo, 0, sizeof(childProcStartupInfo)); childProcStartupInfo.cb = sizeof(childProcStartupInfo); childProcStartupInfo.hStdInput = hFromParent; // stdin childProcStartupInfo.hStdOutput = hToParent; // stdout childProcStartupInfo.hStdError = hToParentDup; // stderr childProcStartupInfo.dwFlags = STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW; childProcStartupInfo.wShowWindow = SW_HIDE; PROCESS_INFORMATION childProcInfo; /* for CreateProcess call */ bOk = CreateProcess( NULL, // filename pCmdLine, // full command line for child NULL, // process security descriptor */ NULL, // thread security descriptor */ TRUE, // inherit handles? Also use if STARTF_USESTDHANDLES */ 0, // creation flags */ NULL, // inherited environment address */ NULL, // startup dir; NULL = start in current */ &childProcStartupInfo, // pointer to startup info (input) */ &childProcInfo); // pointer to process info (output) */ CloseHandle( hFromParent ); CloseHandle( hToParent ); CloseHandle( hToParentDup ); CloseHandle( childProcInfo.hThread); CloseHandle( childProcInfo.hProcess); TerminateProcess( childProcInfo.hProcess ,0); //this is not working, the process thanks

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• How do I patch a Windows API at runtime so that it to returns 0 in x64?

  - by Jorge Vasquez

  In x86, I get the function address using GetProcAddress() and write a simple XOR EAX,EAX; RET; in it. Simple and effective. How do I do the same in x64? bool DisableSetUnhandledExceptionFilter() { const BYTE PatchBytes[5] = { 0x33, 0xC0, 0xC2, 0x04, 0x00 }; // XOR EAX,EAX; RET; // Obtain the address of SetUnhandledExceptionFilter HMODULE hLib = GetModuleHandle( _T("kernel32.dll") ); if( hLib == NULL ) return false; BYTE* pTarget = (BYTE*)GetProcAddress( hLib, "SetUnhandledExceptionFilter" ); if( pTarget == 0 ) return false; // Patch SetUnhandledExceptionFilter if( !WriteMemory( pTarget, PatchBytes, sizeof(PatchBytes) ) ) return false; // Ensures out of cache FlushInstructionCache(GetCurrentProcess(), pTarget, sizeof(PatchBytes)); // Success return true; } static bool WriteMemory( BYTE* pTarget, const BYTE* pSource, DWORD Size ) { // Check parameters if( pTarget == 0 ) return false; if( pSource == 0 ) return false; if( Size == 0 ) return false; if( IsBadReadPtr( pSource, Size ) ) return false; // Modify protection attributes of the target memory page DWORD OldProtect = 0; if( !VirtualProtect( pTarget, Size, PAGE_EXECUTE_READWRITE, &OldProtect ) ) return false; // Write memory memcpy( pTarget, pSource, Size ); // Restore memory protection attributes of the target memory page DWORD Temp = 0; if( !VirtualProtect( pTarget, Size, OldProtect, &Temp ) ) return false; // Success return true; } This example is adapted from code found here: http://www.debuginfo.com/articles/debugfilters.html#overwrite .

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• linux raw socket programming question

  - by user194420

  Hi all, I am trying to create a raw socket which send and receive message with ip/tcp header under linux. I can successfully binds to a port and receive tcp message(ie:syn) However, the message seems to be handled by the os, but not mine. I am just a reader of it(like wireshark). My raw socket binds to port 8888, and then i try to telnet to that port . In wireshark, it shows that the port 8888 reply a "rst ack" when it receive the "syn" request. In my program, it shows that it receive a new message and it doesnot reply with any message. Any way to actually binds to that port?(prevent os handle it) Here is part of my code, i try to cut those error checking for easy reading sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_TCP); int tmp = 1; const int *val = &tmp; setsockopt (sockfd, IPPROTO_IP, IP_HDRINCL, val, sizeof (tmp)); servaddr.sin_family = AF_INET; servaddr.sin_addr.s_addr = htonl(INADDR_ANY); servaddr.sin_port = htons(8888); bind(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr)); //call recv in loop

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• Problem with close socket

  - by zp26

  Hi, I have a problem with my socket program. I create the client program (my code is below) I have a problem when i close the socket with the disconnect method. Can i help me? Thanks and sorry for my English XP CFSocketRef s; -(void)CreaConnessione { CFSocketError errore; struct sockaddr_in sin; CFDataRef address; CFRunLoopSourceRef source; CFSocketContext context = { 0, self, NULL, NULL, NULL }; s = CFSocketCreate( NULL, PF_INET, SOCK_STREAM, IPPROTO_TCP, kCFSocketDataCallBack, AcceptDataCallback, &context); memset(&sin, 0, sizeof(sin)); int port = [fieldPorta.text intValue]; NSString *tempIp = fieldIndirizzo.text; const char *ip = [tempIp UTF8String]; sin.sin_family = AF_INET; sin.sin_port = htons(port); sin.sin_addr.s_addr = (long)inet_addr(ip); address = CFDataCreate(NULL, (UInt8 *)&sin, sizeof(sin)); errore = CFSocketConnectToAddress(s, address, 0); if(errore == 0){ buttonInvioMess.enabled = TRUE; fieldMessaggioInvio.enabled = TRUE; labelTemp.text = [NSString stringWithFormat:@"Connesso al Server"]; CFRelease(address); source = CFSocketCreateRunLoopSource(NULL, s, 0); CFRunLoopAddSource(CFRunLoopGetCurrent(), source, kCFRunLoopDefaultMode); CFRelease(source); CFRunLoopRun(); } else{ labelTemp.text = [NSString stringWithFormat:@"Errore di connessione. Verificare Ip e Porta"]; switchConnection.on = FALSE; } } //the socket doesn't disconnect -(void)Disconnetti{ CFSocketInvalidate(s); CFRelease(s); } -(IBAction)Connetti { if(switchConnection.on) [self CreaConnessione]; else [self Disconnetti]; }

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• error: invalid type argument of '->' (have 'struct node')

  - by Roshan S.A

  Why cant i access the pointer "Cells" like an array ? i have allocated the appropriate memory why wont it act like an array here? it works like an array for a pointer of basic data types. #include<stdio.h> #include<stdlib.h> #include<ctype.h> #define MAX 10 struct node { int e; struct node *next; }; typedef struct node *List; typedef struct node *Position; struct Hashtable { int Tablesize; List Cells; }; typedef struct Hashtable *HashT; HashT Initialize(int SIZE,HashT H) { int i; H=(HashT)malloc(sizeof(struct Hashtable)); if(H!=NULL) { H->Tablesize=SIZE; printf("\n\t%d",H->Tablesize); H->Cells=(List)malloc(sizeof(struct node)* H->Tablesize); should it not act like an array from here on? if(H->Cells!=NULL) { for(i=0;i<H->Tablesize;i++) the following lines are the ones that throw the error { H->Cells[i]->next=NULL; H->Cells[i]->e=i; printf("\n %d",H->Cells[i]->e); } } } else printf("\nError!Out of Space"); } int main() { HashT H; H=Initialize(10,H); return 0; } The error I get is as in the title-error: invalid type argument of '->' (have 'struct node').

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• socket timeout and remove O_NONBLOCK option

  - by juxstapose

  Hello, I implemented a socket timeout and retry but in order to do it I had to set the socket as a non-blocking socket. However, I need the socket to block. This was my attempt at a solution to these two problems. This is not working. Subsequent send calls block but never send any data. When I connect without the select and the timeout, subsequent send calls work normally. References: C: socket connection timeout How to reset a socket back to blocking mode (after I set it to nonblocking mode)? Code: fd_set fdset; struct timeval tv; fcntl(dsock, F_SETFL, O_NONBLOCK); tv.tv_sec = theDeviceTimeout; tv.tv_usec = 0; int retries=0; logi(theLogOutput, LOG_INFO, "connecting to device socket num retrys: %i", theDeviceRetry); for(retries=0;retries<theDeviceRetry;retries++) { connect(dsock, (struct sockaddr *)&daddr, sizeof daddr); FD_ZERO(&fdset); FD_SET(dsock, &fdset); if (select(dsock + 1, NULL, &fdset, NULL, &tv) == 1) { int so_error; socklen_t slen = sizeof so_error; getsockopt(dsock, SOL_SOCKET, SO_ERROR, &so_error, &slen); if (so_error == 0) { logi(theLogOutput, LOG_INFO, "connected to socket on port %i on %s", theDevicePort, theDeviceIP); break; } else { logi(theLogOutput, LOG_WARN, "connect to %i failed on ip %s because %s retries %i", theDevicePort, theDeviceIP, strerror(errno), retries); logi(theLogOutput, LOG_WARN, "failed to connect to device %s", strerror(errno)); logi(theLogOutput, LOG_WARN, "error: %i %s", so_error, strerror(so_error)); continue; } } } int opts; opts = fcntl(dsock,F_GETFL); logi(theLogOutput, LOG_DEBUG, "clearing nonblock option %i retries %i", opts, retries); opts ^= O_NONBLOCK; fcntl(dsock, F_SETFL, opts);

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• Can someone tell me why I'm seg faulting in this simple C program?

  - by user299648

  I keep on getting seg faulted, and for the life of me I dont why. The file I'm scanning is just 18 strings in 18 lines. I thinks the problem is the way I'm mallocing the double pointer called picks, but I dont know exactly why. I'm am only trying to scanf strings that are less than 15 chars long, so I don't see the problem. Can someone please help. #include <stdio.h> #include <stdlib.h> #include <string.h> #define MAX_LENGTH 100 int main( int argc,char *argv[] ) { char* string = malloc( sizeof(char) ); char** picks = malloc(15*sizeof(char)); FILE* pick_file = fopen( argv[l], "r" ); int num_picks; for( num_picks=0 ; fgets( string, MAX_LENGTH, pick_file ) != NULL ; num_picks++ ) { printf("pick a/an %s ", string ); scanf( "%s", picks+num_picks ); } int x; for(x=0; x<num_picks;x++) printf("s\n", picks+x); }

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• Can some tell me why I am seg faulting in this simple C program?

  - by user299648

  I keep on getting seg faulted after I end my first for loop, and for the life of me I don't why. The file I'm scanning is just 18 strings in 18 lines. I thinks the problem is the way I'm mallocing the double pointer called picks, but I don't know exactly why. I'm am only trying to scanf strings that are less than 15 chars long, so I don't see the problem. Can someone please help. #include <stdio.h> #include <stdlib.h> #include <string.h> #define MAX_LENGTH 100 int main( int argc,char *argv[] ) { char* string = malloc( 15*sizeof(char) ); char** picks = malloc(15*sizeof(char*)); FILE* pick_file = fopen( argv[l], "r" ); int num_picks; for( num_picks=0 ; fgets( string, MAX_LENGTH, pick_file ) != NULL ; num_picks++ ) { scanf( "%s", picks+num_picks ); } //this is where i seg fault int x; for(x=0; x<num_picks;x++) printf("s\n", picks+x); }

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• passing argument 1 of 'atoi' makes pointer from integer without a cast....can any body help me..

  - by somasekhar

  #include<stdio.h> #include<string.h> #include<stdlib.h> int main(){ int n; int a,b,ans[10000]; char *c,*d,*e; int i = 0; c = (char*)(malloc(20 * sizeof(char))); d = (char*)(malloc(20 * sizeof(char))); scanf("%d",&n); while(i < n){ scanf("%d",&a); scanf("%d",&b); itoa(a,c,10); itoa(b,d,10); a = atoi(strrev(c)) + atoi(strrev(d)); itoa(a,c,10); e = c; while(*e == '0')e++; ans[i] = atoi(strrev(e)); i++; } i = 0; while(i < n){ printf("%d\n",ans[i]); i++; } }

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• why can't i bind ipv6 socket to a linklocal address

  - by Haiyuan Zhang

  #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> #include <stdio.h> void error(char *msg) { perror(msg); exit(0); } int main(int argc, char *argv[]) { int sock, length, fromlen, n; struct sockaddr_in6 server; struct sockaddr_in6 from; int portNr = 5555; char buf[1024]; length = sizeof (struct sockaddr_in6); sock=socket(AF_INET6, SOCK_DGRAM, 0); if (sock < 0) error("Opening socket"); bzero((char *)&server, length); server.sin6_family=AF_INET6; server.sin6_addr=in6addr_any; server.sin6_port=htons(portNr); inet_pton( AF_INET6, "fe80::21f:29ff:feed:2f7e", (void *)&server.sin6_addr.s6_addr); //inet_pton( AF_INET6, "::1", (void *)&server.sin6_addr.s6_addr); if (bind(sock,(struct sockaddr *)&server,length)<0) error("binding"); fromlen = sizeof(struct sockaddr_in6); while (1) { n = recvfrom(sock,buf,1024,0,(struct sockaddr *)&from,&fromlen); if (n < 0) error("recvfrom"); write(1,"Received a datagram: ",21); write(1,buf,n); n = sendto(sock,"Got your message\n",17, 0,(struct sockaddr *)&from,fromlen); if (n < 0) error("sendto"); } } when I compile and run the above code I got : binding: Invalid argument and if change to bind the ::1 and leave other thing unchanged in the source code, the code works! so could you tell me what's wrong with my code ? thanks in advance.

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• How are two-dimensional arrays formatted in memory?

  - by Chris Cooper

  In C, I know I can dynamically allocate a two-dimensional array on the heap using the following code: int** someNumbers = malloc(arrayRows*sizeof(int*)); for (i = 0; i < arrayRows; i++) { someNumbers[i] = malloc(arrayColumns*sizeof(int)); } Clearly, this actually creates a one-dimensional array of pointers to a bunch of separate one-dimensional arrays of integers, and "The System" can figure you what I mean when I ask for: someNumbers[4][2]; But when I statically declare a 2D array, as in the following line...: int someNumbers[ARRAY_ROWS][ARRAY_COLUMNS]; ...does a similar structure get created on the stack, or is it of another form completely? (i.e. is it a 1D array of pointers? If not, what is it, and how do references to it get figured out?) Also, when I said, "The System," what is actually responsible for figuring that out? The kernel? Or does the C compiler sort it out while compiling?

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• Passing parameter to pthread

  - by Andrei Ciobanu

  Hello, i have the following code: #include <stdlib.h> #include <stdio.h> #include <pthread.h> #define NUM_THREADS 100 struct thread_param { char *f1; char *f2; int x; }; void *thread_function(void *arg){ printf("%d\n", ((struct thread_param*)arg)->x); } int main(int argc, char *argvs[]){ int i, thread_cr_res = 0; pthread_t *threads; threads = malloc(100 * sizeof(*threads)); if(threads == NULL){ fprintf(stderr,"MALLOC THREADS ERROR"); return (-1); } for(i = 0; i < NUM_THREADS; i++){ struct thread_param *tp; if((tp = malloc(sizeof(*tp))) == NULL){ fprintf(stderr,"MALLOC THREAD_PARAM ERROR"); return (-1); } tp->f1 = "f1"; tp->f2 = "f2"; tp->x = i; thread_cr_res = pthread_create(&threads[i], NULL, thread_function, (void*)tp); if(thread_cr_res != 0){ fprintf(stderr,"THREAD CREATE ERROR"); return (-1); } } return (0); } What i want to achieve, is to print all the numbers from 0 to 99, from threads. Also i am experimenting a way to pass a structure as a thread input parameter. What i am finding curios, is that not all the numbers are shown, eg: ./a.out | grep 9 9 19 29 39 49 And sometimes some numbers are shown twice: ... 75 74 89 77 78 79 91 91 Can you please explain me why is this happening ? No errors are shown.

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• How to declare a 2D array of 2D array pointers and access them?

  - by vikramtheone

  Hi Guys, How can I declare an 2D array of 2D Pointers? And later access the individual array elements of the 2D arrays. Is my approach correct? void alloc_2D(int ***memory, unsigned int rows, unsigned int cols); int main() { int i, j; int **ptr; int **array[10][10]; for(i=0;i<10;i++) { for(j=0;j<10;j++) { alloc_2D(&ptr, 10, 10); array[i][j] = ptr; } } //After I do this, how can I access the 10 individual 2D arrays? return 0; } void alloc_2D(int ***memory, unsigned int rows, unsigned int cols) { int **ptr; *memory = NULL; ptr = malloc(rows * sizeof(int*)); if(ptr == NULL) { printf("\nERROR: Memory allocation failed!"); } else { int i; for(i = 0; i< rows; i++) { ptr[i] = malloc(cols * sizeof(float)); if(ptr[i]==NULL) { printf("\nERROR: Memory allocation failed!"); } } } *memory = ptr; }

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• Copying to binary file row of a matrix

  - by Flethuseo

  Hi everyone I want to write each row of a matrix to a binary file. I try writing it like this: vector< vector<uint32_t> > matrix; ... for(size_t i = 0; i < matrix.size(); ++i) ofile->write( reinterpret_cast<char*>(&matrix[i]), sizeof(uint32_t*sizeof(matrix[i])) ); { for(size_t j = 0; j < numcols; ++j) { std::cout << left << setw(10) << matrix[i][j]; } cout << endl; } but it doesn't work, I get garbage numbers. Any help appreciated, Ted.

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• Why is the exception thrown on memcpy using during copying LPBYTE to LPTSTR (clipboard)?

  - by user46503

  Hello, I have a LPBYTE array (taken from file) and I need to copy it into LPTSRT (actually into the clipboard). The trouble is copying work but unstable, sometime an exception was thrown (not always) and I don't understand why. The code is: FILE *fConnect = _wfopen(connectFilePath, _T("rb")); if (!fConnect) return; fseek(fConnect, 0, SEEK_END); lSize = ftell(fConnect); rewind(fConnect); LPBYTE lpByte = (LPBYTE) malloc(lSize); fread(lpByte, 1, lSize, fConnect); lpByte[lSize] = 0; fclose(fConnect); //Copy into clipboard BOOL openRes = OpenClipboard(NULL); if (!openRes) return; DWORD err = GetLastError(); EmptyClipboard(); HGLOBAL hText; hText = GlobalAlloc(GMEM_MOVEABLE, (lSize+ sizeof(TCHAR))); LPTSTR sMem = (TCHAR*)GlobalLock(hText); memcpy(sMem, lpByte, (lSize + sizeof(TCHAR))); The last string is the place where the exception is thrown. Thanks a lot

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• Detect a USB drive being inserted - Windows Service

  - by Tom Bell

  I am trying to detect a USB disk drive being inserted within a Windows Service, I have done this as a normal Windows application. The problem is the following code doesn't work for volumes. Registering the device notification: DEV_BROADCAST_DEVICEINTERFACE notificationFilter; HDEVNOTIFY hDeviceNotify = NULL; ::ZeroMemory(&notificationFilter, sizeof(notificationFilter)); notificationFilter.dbcc_size = sizeof(DEV_BROADCAST_DEVICEINTERFACE); notificationFilter.dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE; notificationFilter.dbcc_classguid = ::GUID_DEVINTERFACE_VOLUME; hDeviceNotify = ::RegisterDeviceNotification(g_serviceStatusHandle, &notificationFilter, DEVICE_NOTIFY_SERVICE_HANDLE); The code from the ServiceControlHandlerEx function: case SERVICE_CONTROL_DEVICEEVENT: PDEV_BROADCAST_HDR pBroadcastHdr = (PDEV_BROADCAST_HDR)lpEventData; switch (dwEventType) { case DBT_DEVICEARRIVAL: ::MessageBox(NULL, "A Device has been plugged in.", "Pounce", MB_OK | MB_ICONINFORMATION); switch (pBroadcastHdr->dbch_devicetype) { case DBT_DEVTYP_DEVICEINTERFACE: PDEV_BROADCAST_DEVICEINTERFACE pDevInt = (PDEV_BROADCAST_DEVICEINTERFACE)pBroadcastHdr; if (::IsEqualGUID(pDevInt->dbcc_classguid, GUID_DEVINTERFACE_VOLUME)) { PDEV_BROADCAST_VOLUME pVol = (PDEV_BROADCAST_VOLUME)pDevInt; char szMsg[80]; char cDriveLetter = ::GetDriveLetter(pVol->dbcv_unitmask); ::wsprintfA(szMsg, "USB disk drive with the drive letter '%c:' has been inserted.", cDriveLetter); ::MessageBoxA(NULL, szMsg, "Pounce", MB_OK | MB_ICONINFORMATION); } } return NO_ERROR; } In a Windows application I am able to get the DBT_DEVTYP_VOLUME in dbch_devicetype, however this isn't present in a Windows Service implementation. Has anyone seen or heard of a solution to this problem, without the obvious, rewrite as a Windows application?

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• Appending unique values only in a linked list in C

  - by LuckySlevin

  typedef struct child {int count; char word[100]; inner_list*next;} child; typedef struct parent { char data [100]; inner_list * head; int count; outer_list * next; } parent; void append(child **q,char num[100],int size) { child *temp,*r,*temp2,*temp3; parent *out=NULL; temp = *q; temp2 = *q; temp3 = *q; char *str; if(*q==NULL) { temp = (child *)malloc(sizeof(child)); strcpy(temp->word,num); temp->count =size; temp->next=NULL; *q=temp; } else { temp = *q; while(temp->next !=NULL) { temp=temp->next; } r = (child *)malloc(sizeof(child)); strcpy(r->word,num); r->count = size; r->next=NULL; temp->next=r; } } This is my append function which I use for adding an element to my child list. But my problem is it only should append unique values which are followed by a string. Which means : Inputs : aaa bbb aaa ccc aaa bbb ccc aaa Append should act : For aaa string there should be a list like bbb->ccc(Not bbb->ccc->bbb since bbb is already there if bbb is coming more than one time it should be increase count only.) For bbb string there should be list like aaa->ccc only For ccc string there should be list like aaa only I hope i could make myself clear. Is there any ideas? Please ask for further info.

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• How to declare array of 2D array pointers and access them?

  - by vikramtheone

  Hi Guys, How can I declare an 2D array of 2D Pointers? And later access the individual array elements of the 2D arrays. Is my approach correct? main() { int i, j; int **array[10][10]; int **ptr = NULL; for(i=0;i<10;i++) { for(j=0j<10;j++) { alloc_2D(&ptr, 10, 10); array[i][j] = ptr; } } //After I do this, how can I access the individual 2D array //and then the individual elements of the 2D arrays? } void alloc_2D(float ***memory, unsigned int rows, unsigned int cols) { float **ptr; *memory = NULL; ptr = malloc(rows * sizeof(float*)); if(ptr == NULL) { status = ERROR; printf("\nERROR: Memory allocation failed!"); } else { int i; for(i = 0; i< rows; i++) { ptr[i] = malloc(cols * sizeof(float)); if(ptr[i]==NULL) { status = ERROR; printf("\nERROR: Memory allocation failed!"); } } } *memory = ptr; }

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• How can i create an n-dimensional array in c

  - by shortCircuit

  I was thinking of making a function that would accept the size of array as a parameter and create a n dimensional array. My room-mate took the liberty of making it complex. He said lets write a function that takes n parameters and returns an n-dimensional array using those parameters as the dimensions. Now i realize an one-day and d array is easy to implement with pointers. For 2d array the snippet would be something like (standard way) : int** x; int* temp; x = (int**)malloc(m * sizeof(int*)); temp = (int*)malloc(m*n * sizeof(int)); for (int i = 0; i < m; i++) { x[i] = temp + (i * n); } where the array is of size m*n; But the problem lies how do we find the nested loop parameters for a n-dimensional array? Is there any way to optimize the code?

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• gluLookAt alternative doesn't work

  - by Brammie

  Hey guys. I'm trying to calculate a lookat matrix myself, instead of using gluLookAt(). My problem is that my matrix doesn't work. using the same parameters on gluLookAt does work however. my way of creating a lookat matrix: Vector3 Eye, At, Up; //these should be parameters =) Vector3 zaxis = At - Eye; zaxis.Normalize(); Vector3 xaxis = Vector3::Cross(Up, zaxis); xaxis.Normalize(); Vector3 yaxis = Vector3::Cross(zaxis, xaxis); yaxis.Normalize(); float r[16] = { xaxis.x, yaxis.x, zaxis.x, 0, xaxis.y, yaxis.y, zaxis.y, 0, xaxis.z, yaxis.z, zaxis.z, 0, 0, 0, 0, 1, }; Matrix Rotation; memcpy(Rotation.values, r, sizeof(r)); float t[16] = { 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, -Eye.x, -Eye.y, -Eye.z, 1, }; Matrix Translation; memcpy(Translation.values, t, sizeof(t)); View = Rotation * Translation; // i tried reversing this as well (translation*rotation) now, when i try to use this matrix be calling glMultMatrixf, nothing shows up in my engine, while using the same eye, lookat and up values on gluLookAt works perfect as i said before. glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glMultMatrixf(View); the problem must be in somewhere in the code i posted here, i know the problem is not in my Vector3/Matrix classes, because they work fine when creating a projection matrix.

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• Ping broadcast on Win XP SP3

  - by PaulH

  I'm trying to ping the broadcast address 255.255.255.255 on WinXP SP3. If I use the command line, I get host error: C:\>ping 255.255.255.255 Ping request could not find host 255.255.255.255. Please check the name and try again. If I try a C++ program using the iphlpapi, IcmpSendEcho() fails and GetLastError returns 11010 IP_REQ_TIMED_OUT. HANDLE h = ::IcmpCreateFile(); IPAddr broadcast = inet_addr( "255.255.255.255" ); BYTE payload[ 32 ] = { 0 }; IP_OPTION_INFORMATION option = { 255, 0, 0, 0, 0 }; // a buffer with room for 32 replies each containing the full payload std::vector< BYTE > replies( 32 * ( sizeof( ICMP_ECHO_REPLY ) + 32 ) ); DWORD res = ::IcmpSendEcho( h, broadcast, payload, sizeof( payload ), &option, &replies[ 0 ], replies.size(), 1000 ); ::IcmpCloseHandle( h ); I can ping the local broadcast 192.168.0.255 with no problem. What do I need to do to ping the global broadcast? Thanks, PaulH

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• Merge n files using a C program

  - by Amal

  I am writing a download Accelerator. So I download a file from the webserver into n parts. Now I want to merge the files into 1 single file. So I use the following code. And the file names are in the correct order. But the output file I am getting is different from the original download file. Can you tell me where could the error be ?C int cbd_merge_files(const char** filenames, int n, const char* final_filename) { FILE* fp = fopen(final_filename, "wb"); if (fp == NULL) return 1; char buffer[4097]; for (int i = 0; i < n; ++i) { const char* fname = filenames[i]; FILE* fp_read = fopen(fname, "rb"); if (fp_read == NULL) return 1; int n; while ((n = fread(buffer, sizeof(char), 4096, fp_read))) { int k = fwrite(buffer, sizeof(char), n, fp); if (!k) return 1; } fclose(fp_read); } fclose(fp); return 0; }

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• sum of square of each elements in the vector using for_each

  - by pierr

  Hi, As the function accepted by for_each take only one parameter (the element of the vector), I have to define a static int sum = 0 somewhere so that It can be accessed after calling the for_each . I think this is awkward. Any better way to do this (still use for_each) ? #include <algorithm> #include <vector> #include <iostream> using namespace std; static int sum = 0; void add_f(int i ) { sum += i * i; } void test_using_for_each() { int arr[] = {1,2,3,4}; vector<int> a (arr ,arr + sizeof(arr)/sizeof(arr[0])); for_each( a.begin(),a.end(), add_f); cout << "sum of the square of the element is " << sum << endl; } In Ruby, We can do it this way: sum = 0 [1,2,3,4].each { |i| sum += i*i} #local variable can be used in the callback function puts sum #=> 30 Would you please show more examples how for_each is typically used in practical programming (not just print out each element)? Is it possible use for_each simulate 'programming pattern' like map and inject in Ruby (or map /fold in Haskell). #map in ruby >> [1,2,3,4].map {|i| i*i} => [1, 4, 9, 16] #inject in ruby [1, 4, 9, 16].inject(0) {|aac ,i| aac +=i} #=> 30 EDIT: Thank you all. I have learned so much from your replies. We have so many ways to do the same single thing in C++ , which makes it a little bit difficult to learn. But it's interesting :)

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• C: incompatible types in assignment

  - by The.Anti.9

  I'm writing a program to check to see if a port is open in C. One line in particular copies one of the arguments to a char array. However, when I try to compile, it says: error: incompatible types in assignment Heres the code. The error is on the assignment of addr #include <sys/socket.h> #include <sys/time.h> #include <sys/types.h> #include <arpa/inet.h> #include <netinet/in.h> #include <errno.h> #include <fcntl.h> #include <stdio.h> #include <netdb.h> #include <stdlib.h> #include <string.h> #include <unistd.h> int main(int argc, char **argv) { u_short port; /* user specified port number */ char addr[1023]; /* will be a copy of the address entered by u */ struct sockaddr_in address; /* the libc network address data structure */ short int sock = -1; /* file descriptor for the network socket */ port = atoi(argv[1]); addr = strncpy(addr, argv[2], 1023); bzero((char *)&address, sizeof(address)); /* init addr struct */ address.sin_addr.s_addr = inet_addr(addr); /* assign the address */ address.sin_port = htons(port); /* translate int2port num */ sock = socket(AF_INET, SOCK_STREAM, 0); if (connect(sock,(struct sockaddr *)&address,sizeof(address)) == 0) { printf("%i is open\n", port); } if (errno == 113) { fprintf(stderr, "Port not open!\n"); } close(sock); return 0; } I'm new to C, so I'm not sure why it would do this.

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• How to access variables in shared memory

  - by user1723361

  I am trying to create a shared memory segment containing three integers and an array. The segment is created and a pointer is attached, but when I try to access the values of the variables (whether changing, printing, etc.) I get a segmentation fault. Here is the code I tried: #include <stdio.h> #include <stdbool.h> #include <stdlib.h> #include <errno.h> #include <sys/types.h> #include <sys/ipc.h> #include <sys/sem.h> #define SIZE 10 int* shm_front; int* shm_end; int* shm_count; int* shm_array; int shm_size = 3*sizeof(int) + sizeof(shm_array[SIZE]); int main(int argc, char* argsv[]) { int shmid; //create shared memory segment if((shmid = shmget(IPC_PRIVATE, shm_size, 0644)) == -1) { printf("error in shmget"); exit(1); } //obtain the pointer to the segment if((shm_front = (int*)shmat(shmid, (void *)0, 0)) == (void *)-1) { printf("error in shmat"); exit(1); } //move down the segment to set the other pointers shm_end = shm_front + 1; shm_count = shm_front + 2; shm_array = shm_front + 3; //tests on shm //*shm_end = 10; //gives segmentation fault //printf("\n%d", *shm_front); //gives segmentation fault //clean-up //get rid of shared memory shmdt(shm_front); shmctl(shmid, IPC_RMID, NULL); //printf("\n\n"); return 0; } I tried accessing the shared memory by dereferencing the pointer to the struct, but got a segmentation fault each time.

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