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  • can't find linker symbol for virtual table

    - by iSight
    Hi, i have the above problem of linker. I have used the code as under: This code has no probem fprintf(stderr, "Top value:%s",(this->topObject())->top()); But, this code is giving the linker problem: fprintf(stderr, "Top value:%s",(this->topObject())->myName()); What could be the reason for this issue

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  • Rule of presidence == over =

    - by robUK
    Hello, I am just wondering would it be better to do this: if((fd = (open(filename, O_RDWR)) == -1)) { fprintf(stderr, "open [ %s ]\n", strerror(errno)); return 1; } or this fd = open(filename, O_RDWR); if((fd == -1) { fprintf(stderr, "open [ %s ]\n", strerror(errno)); return 1; } Many thanks for any suggestions,

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  • gcc run "light" preprocessor

    - by Claudiu
    Is there any way to run the gcc preprocessor, but only for user-defined macros? I have a few one-liners and some #ifdef etc... conditionals, and I want to see what my code looks like when just those are expanded. As it is, the includes get expanded, my fprintf(stderr)s turn into fprintf(((__getreeent())-_stderr), etc...

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  • Storing a NTFS Security Descriptor in C

    - by Doori Bar
    My goal is to store a NTFS Security Descriptor in its identical native state. The purpose is to restore it on-demand. I managed to write the code for that purpose, I was wondering if anybody mind to validate a sample of it? (The for loop represents the way I store the native descriptor) This sample only contains the flag for "OWNER", but my intention is to apply the same method for all of the security descriptor flags. I'm just a beginner, would appreciate the heads up. Thanks, Doori Bar #define _WIN32_WINNT 0x0501 #define WINVER 0x0501 #include <stdio.h> #include <windows.h> #include "accctrl.h" #include "aclapi.h" #include "sddl.h" int main (void) { DWORD lasterror; PSECURITY_DESCRIPTOR PSecurityD1, PSecurityD2; HANDLE hFile; PSID owner; LPTSTR ownerstr; BOOL ownerdefault; int ret = 0; unsigned int i; hFile = CreateFile("c:\\boot.ini", GENERIC_READ | ACCESS_SYSTEM_SECURITY, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, NULL); if (hFile == INVALID_HANDLE_VALUE) { fprintf(stderr,"CreateFile() failed. Error: INVALID_HANDLE_VALUE\n"); return 1; } lasterror = GetSecurityInfo(hFile, SE_FILE_OBJECT, OWNER_SECURITY_INFORMATION , &owner, NULL, NULL, NULL, &PSecurityD1); if (lasterror != ERROR_SUCCESS) { fprintf(stderr,"GetSecurityInfo() failed. Error: %lu;\n", lasterror); ret = 1; goto ret1; } ConvertSidToStringSid(owner,&ownerstr); printf("ownerstr of PSecurityD1: %s\n", ownerstr); /* The for loop represents the way I store the native descriptor */ PSecurityD2 = malloc( GetSecurityDescriptorLength(PSecurityD1) * sizeof(unsigned char) ); for (i=0; i < GetSecurityDescriptorLength(PSecurityD1); i++) ((unsigned char *) PSecurityD2)[i] = ((unsigned char *) PSecurityD1)[i]; if (IsValidSecurityDescriptor(PSecurityD2) == 0) { fprintf(stderr,"IsValidSecurityDescriptor(PSecurityD2) failed.\n"); ret = 2; goto ret2; } if (GetSecurityDescriptorOwner(PSecurityD2,&owner,&ownerdefault) == 0) { fprintf(stderr,"GetSecurityDescriptorOwner() failed."); ret = 2; goto ret2; } ConvertSidToStringSid(owner,&ownerstr); printf("ownerstr of PSecurityD2: %s\n", ownerstr); ret2: free(owner); free(ownerstr); free(PSecurityD1); free(PSecurityD2); ret1: CloseHandle(hFile); return ret; }

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  • Rule of precedence == over =

    - by robUK
    Hello, I am just wondering would it be better to do this: if((fd = open(filename, O_RDWR)) == -1) { fprintf(stderr, "open [ %s ]\n", strerror(errno)); return 1; } or this fd = open(filename, O_RDWR); if(fd == -1) { fprintf(stderr, "open [ %s ]\n", strerror(errno)); return 1; } Many thanks for any suggestions,

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  • a program similar to ls with some modifications

    - by Bond
    Hi, here is a simple puzzle I wanted to discuss. A C program to take directory name as command line argument and print last 3 directories and 3 files in all subdirectories without using api 'system' inside it. suppose directory bond0 contains bond1, di2, bond3, bond4, bond5 and my_file1, my_file2, my_file3, my_file4, my_file5, my_file6 and bond1 contains bond6 my_file7 my_file8 my_file9 my_file10 program should output - bond3, bond4, bond5, my_file4, my_file5, my_file6, bond6, my_file8, my_file9, my_file10 My code for the above problem is here #include<dirent.h> #include<unistd.h> #include<string.h> #include<sys/stat.h> #include<stdlib.h> #include<stdio.h> char *directs[20], *files[20]; int i = 0; int j = 0; int count = 0; void printdir(char *); int count_dirs(char *); int count_files(char *); int main() { char startdir[20]; printf("Scanning user directories\n"); scanf("%s", startdir); printdir(startdir); } void printdir(char *dir) { printf("printdir called %d directory is %s\n", ++count, dir); DIR *dp = opendir(dir); int nDirs, nFiles, nD, nF; nDirs = 0; nFiles = 0; nD = 0; nF = 0; if (dp) { struct dirent *entry = 0; struct stat statBuf; nDirs = count_dirs(dir); nFiles = count_files(dir); printf("The no of subdirectories in %s is %d \n", dir, nDirs); printf("The no of files in %s is %d \n", dir, nFiles); while ((entry = readdir(dp)) != 0) { if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) { continue; } char *filepath = malloc(strlen(dir) + strlen(entry->d_name) + 2); if (filepath) { sprintf(filepath, "%s/%s", dir, entry->d_name); if (lstat(filepath, &statBuf) != 0) { } if (S_ISDIR(statBuf.st_mode)) { nD++; if ((nDirs - nD) < 3) { printf("The directory is %s\n",entry->d_name); } } else { nF++; if ((nFiles - nF) < 3) { printf("The files are %s\n", entry->d_name); } //if } //else free(filepath); } //if(filepath) } //while while ((entry = readdir(dp)) != 0) { if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) { continue; } printf("In second while loop *entry=%s\n",entry->d_name); char *filepath = malloc(strlen(dir) + strlen(entry->d_name) + 2); if (filepath) { sprintf(filepath, "%s/%s", dir, entry->d_name); if (lstat(filepath, &statBuf) != 0) { } if (S_ISDIR(statBuf.st_mode)) { printdir(entry->d_name); } } //else free(filepath); } //2nd while closedir(dp); } else { fprintf(stderr, "Error, cannot open directory %s\n", dir); } } //printdir int count_dirs(char *dir) { DIR *dp = opendir(dir); int nD; nD = 0; if (dp) { struct dirent *entry = 0; struct stat statBuf; while ((entry = readdir(dp)) != 0) { if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) { continue; } char *filepath = malloc(strlen(dir) + strlen(entry->d_name) + 2); if (filepath) { sprintf(filepath, "%s/%s", dir, entry->d_name); if (lstat(filepath, &statBuf) != 0) { fprintf(stderr, "File Not found? %s\n", filepath); } if (S_ISDIR(statBuf.st_mode)) { nD++; } else { continue; } free(filepath); } } closedir(dp); } else { fprintf(stderr, "Error, cannot open directory %s\n", dir); } return nD; } int count_files(char *dir) { DIR *dp = opendir(dir); int nF; nF = 0; if (dp) { struct dirent *entry = 0; struct stat statBuf; while ((entry = readdir(dp)) != 0) { if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) { continue; } char *filepath = malloc(strlen(dir) + strlen(entry->d_name) + 2); if (filepath) { sprintf(filepath, "%s/%s", dir, entry->d_name); if (lstat(filepath, &statBuf) != 0) { fprintf(stderr, "File Not found? %s\n", filepath); } if (S_ISDIR(statBuf.st_mode)) { continue; } else { nF++; } free(filepath); } } closedir(dp); } else { fprintf(stderr, "Error, cannot open file %s\n", dir); } return nF; } The above code I wrote is a bit not functioning correctly can some one help me to understand the error which is coming.So that I improve it further.There seems to be some small glitch which is not clear to me right now.

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  • Sockets: Transport endpoint is not connected on send

    - by TheoretiCAL
    I'm trying to learn socket programming from http://beej.us/guide/bgnet/output/html/singlepage/bgnet.html and am attempting to build a SOCK_STREAM client/server. My client: #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <netdb.h> #define SERVERPORT "4951" // the port users will be connecting to int main(int argc, char *argv[]) { int sockfd; struct addrinfo hints, *servinfo, *p; int rv; int numbytes; if (argc != 3) { fprintf(stderr,"usage: talker hostname message\n"); exit(1); } memset(&hints, 0, sizeof hints); hints.ai_family = AF_UNSPEC; hints.ai_socktype = SOCK_STREAM; if ((rv = getaddrinfo(argv[1], SERVERPORT, &hints, &servinfo)) != 0) { fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv)); return 1; } // loop through all the results and make a socket for(p = servinfo; p != NULL; p = p->ai_next) { if ((sockfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) { perror("talker: socket"); continue; if (connect(sockfd, p->ai_addr, p->ai_addrlen) == -1) { close(sockfd); perror("client: connect"); continue; } } break; } if (p == NULL) { fprintf(stderr, "talker: failed to bind socket\n"); return 2; } if ((numbytes = send(sockfd, argv[2], strlen(argv[2]), 0) == -1)) { perror("talker: send"); exit(1); } freeaddrinfo(servinfo); printf("talker: sent %d bytes to %s\n", numbytes, argv[1]); close(sockfd); return 0; } Server: #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <netdb.h> #define MYPORT "4951" // the port users will be connecting to #define MAXBUFLEN 100 static int backlog = 10; // get sockaddr, IPv4 or IPv6: void *get_in_addr(struct sockaddr *sa) { if (sa->sa_family == AF_INET) { return &(((struct sockaddr_in*)sa)->sin_addr); } return &(((struct sockaddr_in6*)sa)->sin6_addr); } int main(void) { int sockfd; struct addrinfo hints, *servinfo, *p; int rv; int numbytes; int new_fd; socklen_t addr_size; struct sockaddr_storage their_addr; char buf[MAXBUFLEN]; char s[INET6_ADDRSTRLEN]; memset(&hints, 0, sizeof hints); hints.ai_family = AF_UNSPEC; // set to AF_INET to force IPv4 hints.ai_socktype = SOCK_STREAM; hints.ai_flags = AI_PASSIVE; // use my IP if ((rv = getaddrinfo(NULL, MYPORT, &hints, &servinfo)) != 0) { fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv)); return 1; } // loop through all the results and bind to the first we can for(p = servinfo; p != NULL; p = p->ai_next) { if ((sockfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) { perror("listener: socket"); continue; } int yes=1; // lose the pesky "Address already in use" error message if (setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&yes,sizeof(int)) == -1) { perror("setsockopt"); exit(1); } if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) { close(sockfd); perror("listener: bind"); continue; } if (listen(sockfd,backlog) == -1){ close(sockfd); perror("listener:listen"); continue; } break; } if (p == NULL) { fprintf(stderr, "listener: failed to bind socket\n"); return 2; } freeaddrinfo(servinfo); printf("listener: waiting to recv..\n"); while(1){ addr_size = sizeof their_addr; if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &addr_size))==-1){ perror("accept"); exit(1); } if ((numbytes = recv(new_fd, buf, MAXBUFLEN-1 , 0) == -1)) { perror("recv"); exit(1); } printf("listener: got packet from %s\n", inet_ntop(their_addr.ss_family, get_in_addr((struct sockaddr *)&their_addr), s, sizeof s)); printf("listener: packet is %d bytes long\n", numbytes); buf[numbytes] = '\0'; printf("listener: packet contains \"%s\"\n", buf); close(sockfd); } return 0; } Upon executing the client, I get " send: Transport endpoint is not connected" and I'm not sure where I went wrong. Thanks.

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  • std::map for storing static const Objects

    - by Sean M.
    I am making a game similar to Minecraft, and I am trying to fine a way to keep a map of Block objects sorted by their id. This is almost identical to the way that Minecraft does it, in that they declare a bunch of static final Block objects and initialize them, and then the constructor of each block puts a reference of that block into whatever the Java equivalent of a std::map is, so there is a central place to get ids and the Blocks with those ids. The problem is, that I am making my game in C++, and trying to do the exact same thing. In Block.h, I am declaring the Blocks like so: //Block.h public: static const Block Vacuum; static const Block Test; And in Block.cpp I am initializing them like so: //Block.cpp const Block Block::Vacuum = Block("Vacuum", 0, 0); const Block Block::Test = Block("Test", 1, 0); The block constructor looks like this: Block::Block(std::string name, uint16 id, uint8 tex) { //Check for repeat ids if (IdInUse(id)) { fprintf(stderr, "Block id %u is already in use!", (uint32)id); throw std::runtime_error("You cannot reuse block ids!"); } _id = id; //Check for repeat names if (NameInUse(name)) { fprintf(stderr, "Block name %s is already in use!", name); throw std::runtime_error("You cannot reuse block names!"); } _name = name; _tex = tex; //fprintf(stdout, "Using texture %u\n", _tex); _transparent = false; _solidity = 1.0f; idMap[id] = this; nameMap[name] = this; } And finally, the maps that I'm using to store references of Blocks in relation to their names and ids are declared as such: std::map<uint16, Block*> Block::idMap = std::map<uint16, Block*>(); //The map of block ids std::map<std::string, Block*> Block::nameMap = std::map<std::string, Block*>(); //The map of block names The problem comes when I try to get the Blocks in the maps using a method called const Block* GetBlock(uint16 id), where the last line is return idMap.at(id);. This line returns a Block with completely random values like _visibility = 0xcccc and such like that, found out through debugging. So my question is, is there something wrong with the blocks being declared as const obejcts, and then stored at pointers and accessed later on? The reason I cant store them as Block& is because that makes a copy of the Block when it is entered, so the block wouldn't have any of the attributes that could be set afterwards in the constructor of any child class, so I think I need to store them as a pointer. Any help is greatly appreciated, as I don't fully understand pointers yet. Just ask if you need to see any other parts of the code.

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  • Binary files printing and desired precision

    - by yCalleecharan
    Hi, I'm printing a variable say z1 which is a 1-D array containing floating point numbers to a text file so that I can import into Matlab or GNUPlot for plotting. I've heard that binary files (.dat) are smaller than .txt files. The definition that I currently use for printing to a .txt file is: void create_out_file(const char *file_name, const long double *z1, size_t z_size){ FILE *out; size_t i; if((out = _fsopen(file_name, "w+", _SH_DENYWR)) == NULL){ fprintf(stderr, "***> Open error on output file %s", file_name); exit(-1); } for(i = 0; i < z_size; i++) fprintf(out, "%.16Le\n", z1[i]); fclose(out); } I have three questions: Are binary files really more compact than text files?; If yes, I would like to know how to modify the above code so that I can print the values of the array z1 to a binary file. I've read that fprintf has to be replaced with fwrite. My output file say dodo.dat should contain the values of array z1 with one floating number per line. I have %.16Le up in my code but I think that %.15Le is right as I have 15 precision digits with long double. I have put a dot (.) in the width position as I believe that this allows expansion to an arbitrary field to hold the desired number. Am I right? As an example with %.16Le, I can have an output like 1.0047914240730432e-002 which gives me 16 precision digits and the width of the field has the right width to display the number correctly. Is placing a dot (.) in the width position instead of a width value a good practice? Thanks a lot...

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  • How can i get rid of 0xFEEFEE in VC

    - by egebilmuh
    Hi guys I m programming C for an assingment in VC++ 2008. I simulate adjList for graph implementation. i can readly add edge between two vertex and print the graph. and i want to remove edge between two vertex and print the graph again. whatever i do,i cant print the graph after deleting the edge. i get 0xfeefee :( what is this? and how can i resolve this program. my delete function and print the graph function are illustrated below. void deleteEdge(Graph G, Vertex V, Vertex W) { Edge list,prev,temp; list=V->list; prev=NULL; // while(list!=NULL && list->to->value!=W->value){ prev=list; list=list->next; } // have found the element. if(list!=NULL){ temp=list; // if first element of list is deleted. if(prev==NULL) list=list->next; else prev->next=list->next; // reallocate. free(temp); } } void GRAPHprint(Graph G) { Vertex tmp; Edge list; for(tmp = G->head;tmp!=NULL;tmp=tmp->next) { fprintf(stdout,"V:%d\t",tmp->value); list=tmp->list; while(list!=NULL) { fprintf(stdout,"%d\t",list->to->value); list=list->next; } fprintf(stdout, "\n"); } system("pause"); }

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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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  • fopen / fopen_s and writing to files

    - by yCalleecharan
    Hi, I'm using fopen in C to write the output to a text file. The function declaration is (where ARRAY_SIZE has been defined earlier): void create_out_file(char file_name[],long double *z1){ FILE *out; int i; if((out = fopen(file_name, "w+")) == NULL){ fprintf(stderr, "* Open error on output file %s", file_name); exit(-1); } for(i = 0; i < ARRAY_SIZE; i++) fprintf(out, "%.16Le\n", z1[i]); fclose(out); } My questions: On compilation with MVS2008 I get the warning: warning C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. I haven't see much information on fopen_s so that I can change my code. Any suggestions? Can one instruct fprintf to write at desired precision? If I'm using long double then I assume that my answers are good till 15 digits after the decimal point. Am I right? Thanks a lot...

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  • Reciving UDP packets on iPhone

    - by Eli
    I'm trying to establish UDP communication between a MAC OS and an iPod through Wi-Fi, at this point I'm able to send packets from the iPod and I can see those packets have the right MAC and ip addresses (I'm using wireshark to monitor the network) but the MAC receives the packets only when the wireshark is on, otherwise recvfrom() returns -1. When I try to transmit from MAC to iPhone I have the same result, I can see the packets are sent but the iPhone doesn't seem to get them. I'm using the next code to send: struct addrinfo hints; int rv; memset(&hints, 0, sizeof hints); hints.ai_family = AF_UNSPEC; hints.ai_socktype = SOCK_DGRAM; if ((rv = getaddrinfo(IP, SERVERPORT, &hints, &servinfo)) != 0) { fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv)); return 1; } // loop through all the results and make a socket for(p = servinfo; p != NULL; p = p->ai_next) { if ((sockfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) { perror("talker: socket"); continue; } break; } if (p == NULL) { fprintf(stderr, "talker: failed to bind socket\n"); return 2; } while (cond) sntBytes += sendto(sockfd, message, strlen(message), 0, p->ai_addr, p->ai_addrlen); return 0; and this code to receive: struct addrinfo hints, *p; int rv; memset(&hints, 0, sizeof hints); hints.ai_family = AF_UNSPEC; // set hints.ai_socktype = SOCK_DGRAM; hints.ai_flags = AI_PASSIVE; // use to AF_INET to force IPv4 my IP if ((rv = getaddrinfo(NULL, MYPORT, &hints, &servinfo)) != 0) { fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv)); return 1; } // loop through all the results and bind to the first we can for(p = servinfo; p != NULL; p = p->ai_next) { if ((sockfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) { perror("listener: socket"); continue; } if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) { close(sockfd); perror("listener: bind"); continue; } break; } if (p == NULL) { fprintf(stderr, "listener: failed to bind socket\n"); return 2; } addr_len = sizeof their_addr; fcntl(sockfd, F_SETFL,O_NONBLOCK); int rcvbuf_size = 128 * 1024; // That's 128Kb of buffer space. setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &rcvbuf_size, sizeof(rcvbuf_size)); printf("listener: waiting to recvfrom...\n"); while (cond) rcvBytes = recvfrom(sockfd, buf, MAXBUFLEN-1 , 0, (struct sockaddr *)&their_addr, &addr_len); return 0; What am I missing?

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  • Compiler issues on VC++ 2008 Express, Seemingly correct code throws errors.

    - by Anthony Clever
    Hi there, I've been trying to get back into coding for a while, so I figured I'd start with some simple SDL, now, without the file i/o, this compiles fine, but when I throw in the stdio code, it starts throwing errors. This I'm not sure about, I don't see any problem with the code itself, however, like I said, I might as well be a newbie, and figured I'd come here to get someone with a little more experience with this type of thing to look at it. I guess my question boils down to: "Why doesn't this compile under Microsoft's Visual C++ 2008 Express?" I've attached the error log at the bottom of the code snippet. Thanks in advance for any help. #include "SDL/SDL.h" #include "stdio.h" int main(int argc, char *argv[]) { FILE *stderr; FILE *stdout; stderr = fopen("stderr", "wb"); stdout = fopen("stdout", "wb"); SDL_Init(SDL_INIT_EVERYTHING); fprintf(stdout, "SDL INITIALIZED SUCCESSFULLY\n"); SDL_Quit(); fprintf(stderr, "SDL QUIT.\n"); fclose(stderr); fclose(stdout); return 0; } /* 1>------ Build started: Project: opengl_crap, Configuration: Debug Win32 ------ 1>Compiling... 1>main.cpp 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(6) : error C2090: function returns array 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(6) : error C2528: '__iob_func' : pointer to reference is illegal 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(6) : error C2556: 'FILE ***__iob_func(void)' : overloaded function differs only by return type from 'FILE *__iob_func(void)' 1> c:\program files\microsoft visual studio 9.0\vc\include\stdio.h(132) : see declaration of '__iob_func' 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(7) : error C2090: function returns array 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(7) : error C2528: '__iob_func' : pointer to reference is illegal 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(9) : error C2440: '=' : cannot convert from 'FILE *' to 'FILE ***' 1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(10) : error C2440: '=' : cannot convert from 'FILE *' to 'FILE ***' 1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(13) : error C2664: 'fprintf' : cannot convert parameter 1 from 'FILE ***' to 'FILE *' 1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(15) : error C2664: 'fprintf' : cannot convert parameter 1 from 'FILE ***' to 'FILE *' 1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(17) : error C2664: 'fclose' : cannot convert parameter 1 from 'FILE ***' to 'FILE *' 1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast 1>c:\documents and settings\owner\my documents\visual studio 2008\projects\opengl_crap\opengl_crap\main.cpp(18) : error C2664: 'fclose' : cannot convert parameter 1 from 'FILE ***' to 'FILE *' 1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast 1>Build log was saved at "file://c:\Documents and Settings\Owner\My Documents\Visual Studio 2008\Projects\opengl_crap\opengl_crap\Debug\BuildLog.htm" 1>opengl_crap - 11 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== */

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  • Make file Linking issue Undefined symbols for architecture x86_64

    - by user1035839
    I am working on getting a few files to link together using my make file and c++ and am getting the following error when running make. g++ -bind_at_load `pkg-config --cflags opencv` -c -o compute_gist.o compute_gist.cpp g++ -bind_at_load `pkg-config --cflags opencv` -c -o gist.o gist.cpp g++ -bind_at_load `pkg-config --cflags opencv` -c -o standalone_image.o standalone_image.cpp g++ -bind_at_load `pkg-config --cflags opencv` -c -o IplImageConverter.o IplImageConverter.cpp g++ -bind_at_load `pkg-config --cflags opencv` -c -o GistCalculator.o GistCalculator.cpp g++ -bind_at_load `pkg-config --cflags opencv` `pkg-config --libs opencv` compute_gist.o gist.o standalone_image.o IplImageConverter.o GistCalculator.o -o rungist Undefined symbols for architecture x86_64: "color_gist_scaletab(color_image_t*, int, int, int const*)", referenced from: _main in compute_gist.o ld: symbol(s) not found for architecture x86_64 collect2: ld returned 1 exit status make: *** [rungist] Error 1 My makefile is as follows (Note, I don't need opencv bindings yet, but will be coding in opencv later. CXX = g++ CXXFLAGS = -bind_at_load `pkg-config --cflags opencv` LFLAGS = `pkg-config --libs opencv` SRC = \ compute_gist.cpp \ gist.cpp \ standalone_image.cpp \ IplImageConverter.cpp \ GistCalculator.cpp OBJS = $(SRC:.cpp=.o) rungist: $(OBJS) $(CXX) $(CXXFLAGS) $(LFLAGS) $(OBJS) -o $@ all: rungist clean: rm -rf $(OBJS) rungist The method header is located in gist.h float *color_gist_scaletab(color_image_t *src, int nblocks, int n_scale, const int *n_orientations); And the method is defined in gist.cpp float *color_gist_scaletab(color_image_t *src, int w, int n_scale, const int *n_orientation) { And finally the compute_gist.cpp (main file) #include <stdio.h> #include <stdlib.h> #include <string.h> #include "gist.h" static color_image_t *load_ppm(const char *fname) { FILE *f=fopen(fname,"r"); if(!f) { perror("could not open infile"); exit(1); } int width,height,maxval; if(fscanf(f,"P6 %d %d %d",&width,&height,&maxval)!=3 || maxval!=255) { fprintf(stderr,"Error: input not a raw PPM with maxval 255\n"); exit(1); } fgetc(f); /* eat the newline */ color_image_t *im=color_image_new(width,height); int i; for(i=0;i<width*height;i++) { im->c1[i]=fgetc(f); im->c2[i]=fgetc(f); im->c3[i]=fgetc(f); } fclose(f); return im; } static void usage(void) { fprintf(stderr,"compute_gist options... [infilename]\n" "infile is a PPM raw file\n" "options:\n" "[-nblocks nb] use a grid of nb*nb cells (default 4)\n" "[-orientationsPerScale o_1,..,o_n] use n scales and compute o_i orientations for scale i\n" ); exit(1); } int main(int argc,char **args) { const char *infilename="/dev/stdin"; int nblocks=4; int n_scale=3; int orientations_per_scale[50]={8,8,4}; while(*++args) { const char *a=*args; if(!strcmp(a,"-h")) usage(); else if(!strcmp(a,"-nblocks")) { if(!sscanf(*++args,"%d",&nblocks)) { fprintf(stderr,"could not parse %s argument",a); usage(); } } else if(!strcmp(a,"-orientationsPerScale")) { char *c; n_scale=0; for(c=strtok(*++args,",");c;c=strtok(NULL,",")) { if(!sscanf(c,"%d",&orientations_per_scale[n_scale++])) { fprintf(stderr,"could not parse %s argument",a); usage(); } } } else { infilename=a; } } color_image_t *im=load_ppm(infilename); //Here's the method call -> :( float *desc=color_gist_scaletab(im,nblocks,n_scale,orientations_per_scale); int i; int descsize=0; //compute descriptor size for(i=0;i<n_scale;i++) descsize+=nblocks*nblocks*orientations_per_scale[i]; descsize*=3; // color //print descriptor for(i=0;i<descsize;i++) printf("%.4f ",desc[i]); printf("\n"); free(desc); color_image_delete(im); return 0; } Any help would be greatly appreciated. I hope this is enough info. Let me know if I need to add more.

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  • File Segmentation when trying to write in a file

    - by user1286390
    I am trying in C language to use the method of bisection to find the roots of some equation, however when I try to write every step of this process in a file I get the problem "Segmentation fault". This might be an idiot fault that I did, however I have been trying to solve this for a long time. I am compiling using gcc and that is the code: #include <stdio.h> #include <stdlib.h> #include <math.h> #define R 1.0 #define h 1.0 double function(double a); void attractor(double *a1, double *a2, double *epsilon); void attractor(double *a1, double *a2, double *epsilon) { FILE* bisection; double a2_copia, a3, fa1, fa2; bisection = fopen("bisection-part1.txt", "w"); fa1 = function(*a1); fa2 = function(*a2); if(function(*a1) - function(*a2) > 0.0) *epsilon = function(*a1) - function(*a2); else *epsilon = function(*a2) - function(*a1); fprintf(bisection, "a1 a2 fa1 fa2 epsilon\n"); a2_copia = 0.0; if(function(*a1) * function(*a2) < 0.0 && *epsilon >= 0.00001) { a3 = *a2 - (*a2 - *a1); a2_copia = *a2; *a2 = a3; if(function(*a1) - function(*a2) > 0.0) *epsilon = function(*a1) - function(*a2); else *epsilon = function(*a2) - function(*a1); if(function(*a1) * function(*a2) < 0.0 && *epsilon >= 0.00001) { fprintf(bisection, "%.4f %.4f %.4f %.4f %.4f\n", *a1, *a2, function(*a1), function(*a1), *epsilon); attractor(a1, a2, epsilon); } else { *a2 = a2_copia; *a1 = a3; if(function(*a1) - function(*a2) > 0) *epsilon = function(*a1) - function(*a2); else *epsilon = function(*a2) - function(*a1); if(function(*a1) * function(*a2) < 0.0 && *epsilon >= 0.00001) { fprintf(bisection, "%.4f %.4f %.4f %.4f %.4f\n", *a1, *a2, function(*a1), function(*a1), *epsilon); attractor(a1, a2, epsilon); } } } fa1 = function(*a1); fa2 = function(*a2); if(function(*a1) - function(*a2) > 0.0) *epsilon = function(*a1) - function(*a2); else *epsilon = function(*a2) - function(*a1); fprintf(bisection, "%.4f %.4f %.4f %.4f %.4f\n", a1, a2, fa1, fa2, epsilon); } double function(double a) { double fa; fa = (a * cosh(h / (2 * a))) - R; return fa; } int main() { double a1, a2, fa1, fa2, epsilon; a1 = 0.1; a2 = 0.5; fa1 = function(a1); fa2 = function(a2); if(fa1 - fa2 > 0.0) epsilon = fa1 - fa2; else epsilon = fa2 - fa1; if(epsilon >= 0.00001) { fa1 = function(a1); fa2 = function(a2); attractor(&a1, &a2, &epsilon); fa1 = function(a1); fa2 = function(a2); if(fa1 - fa2 > 0.0) epsilon = fa1 - fa2; else epsilon = fa2 - fa1; } if(epsilon < 0.0001) printf("Vanish at %f", a2); else printf("ERROR"); return 0; } Thanks anyway and sorry if this question is not suitable.

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  • Wincap capture filtering expression syntax

    - by cpx
    How would specify a syntax for filtering tcp server port with its ip address? const char *packet_filter = "tcp src port 2054"; bpf_u_int32 netmask; bpf_program fcode; if (d->addresses != NULL) /* Retrieve the mask of the first address of the interface */ netmask=((struct sockaddr_in *)(d->addresses->netmask))->sin_addr.S_un.S_addr; else /* If the interface is without an address we suppose to be in a C class network */ netmask=0xffffff; //compile the filter if (pcap_compile(adhandle, &fcode, packet_filter, 1, netmask) < 0) { fprintf(stderr,"\nUnable to compile the packet filter. Check the syntax.\n"); /* Free the device list */ pcap_freealldevs(alldevs); return -1; } //set the filter if (pcap_setfilter(adhandle, &fcode) < 0) { fprintf(stderr,"\nError setting the filter.\n"); /* Free the device list */ pcap_freealldevs(alldevs); return -1; }

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  • Time complexity of a sorting algorithm

    - by Passonate Learner
    The two programs below get n integers from file and calculates the sum of ath to bth integers q(number of question) times. I think the upper program has worse time complexity than the lower, but I'm having problems calculating the time complexity of these two algorithms. [input sample] 5 3 5 4 3 2 1 2 3 3 4 2 4 [output sample] 7 5 9 Program 1: #include <stdio.h> FILE *in=fopen("input.txt","r"); FILE *out=fopen("output.txt","w"); int n,q,a,b,sum; int data[1000]; int main() int i,j; fscanf(in,"%d%d",&n,&q); for(i=1;i<=n;i++) fscanf(in,"%d",&data[i]); for i=0;i<q;i++) { fscanf(in,"%d%d",&a,&b); sum=0; for(j=a;j<=b;j++) sum+=data[j]; fprintf(out,"%d\n",sum); } return 0; } Program 2: #include <stdio.h> FILE *in=fopen("input.txt","r"); FILE *out=fopen("output.txt","w"); int n,q,a,b; int data[1000]; int sum[1000]; int main() { int i,j; fscanf(in,"%d%d",&n,&q); for(i=1;i<=n;i++) fscanf(in,"%d",&data[i]); for(i=1;i<=n;i++) sum[i]=sum[i-1]+data[i]; for(i=0;i<q;i++) { fscanf(in,"%d%d",&a,&b); fprintf(out,"%d\n",sum[b]-sum[a-1]); } return 0; } The programs below gets n integers from 1 to m and sorts them. Again, I cannot calculate the time complexity. [input sample] 5 5 2 1 3 4 5 [output sample] 1 2 3 4 5 Program: #include <stdio.h> FILE *in=fopen("input.txt","r") FILE *out=fopen("output.txt","w") int n,m; int data[1000]; int count[1000]; int main() { int i,j; fscanf(in,"%d%d",&n,&m); for(i=0;i<n;i++) { fscanf(in,"%d",&data[i]); count[data[i]]++ } for(i=1;i<=m;i++) { for(j=0;j<count[i];j++) fprintf(out,"%d ",i); } return 0; } It's ironic(or not) that I cannot calculate the time complexity of my own algorithms, but I have passions to learn, so please programming gurus, help me!

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  • Problems with this stack implementation

    - by Andersson Melo
    where is the mistake? My code here: typedef struct _box { char *dados; struct _box * proximo; } Box; typedef struct _pilha { Box * topo; }Stack; void Push(Stack *p, char * algo) { Box *caixa; if (!p) { exit(1); } caixa = (Box *) calloc(1, sizeof(Box)); caixa->dados = algo; caixa->proximo = p->topo; p->topo = caixa; } char * Pop(Stack *p) { Box *novo_topo; char * dados; if (!p) { exit(1); } if (p->topo==NULL) return NULL; novo_topo = p->topo->proximo; dados = p->topo->dados; free(p->topo); p->topo = novo_topo; return dados; } void StackDestroy(Stack *p) { char * c; if (!p) { exit(1); } c = NULL; while ((c = Pop(p)) != NULL) { free(c); } free(p); } int main() { int conjunto = 1; char p[30]; int flag = 0; Stack *pilha = (Stack *) calloc(1, sizeof(Stack)); FILE* arquivoIN = fopen("L1Q3.in","r"); FILE* arquivoOUT = fopen("L1Q3.out","w"); if (arquivoIN == NULL) { printf("Erro na leitura do arquivo!\n\n"); exit(1); } fprintf(arquivoOUT,"Conjunto #%d\n",conjunto); while (fscanf(arquivoIN,"%s", p) != EOF ) { if (pilha->topo == NULL && flag != 0) { conjunto++; fprintf(arquivoOUT,"\nConjunto #%d\n",conjunto); } if(strcmp(p, "return") != 0) { Push(pilha, p); } else { p = Pop(pilha); if(p != NULL) { fprintf(arquivoOUT, "%s\n", p); } } flag = 1; } StackDestroy(pilha); return 0; } The Pop function returns the string value read from file. But is not correct and i don't know why.

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  • Why does this XML validation via XSD fail in libxml2 (but succeed in xmllint) and how do I fix it?

    - by mtree
    If I run this XML validation via xmllint: xmllint --noout --schema schema.xsd test.xml I get this success message: .../test.xml validates However if I run the same validation via libxml2's C API: int result = xmlSchemaValidateDoc(...) I get a return value of 1845 and this failure message: Element '{http://example.com/XMLSchema/1.0}foo': No matching global declaration available for the validation root. Which I can make absolutely no sense of. :( schema.xsd: <?xml version="1.0" encoding="utf-8" ?> <!DOCTYPE xs:schema PUBLIC "-//W3C//DTD XMLSCHEMA 200102//EN" "XMLSchema.dtd" > <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://example.com/XMLSchema/1.0" targetNamespace="http://example.com/XMLSchema/1.0" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xs:element name="foo"> </xs:element> </xs:schema> test.xml: <?xml version="1.0" encoding="UTF-8"?> <foo xmlns="http://example.com/XMLSchema/1.0"> </foo> main.c: #include <stdio.h> #include <sys/stat.h> #include <sys/types.h> #include <string.h> #include <libxml/parser.h> #include <libxml/valid.h> #include <libxml/xmlschemas.h> u_int32_t get_file_size(const char *file_name) { struct stat buf; if ( stat(file_name, &buf) != 0 ) return(0); return (unsigned int)buf.st_size; } void handleValidationError(void *ctx, const char *format, ...) { char *errMsg; va_list args; va_start(args, format); vasprintf(&errMsg, format, args); va_end(args); fprintf(stderr, "Validation Error: %s", errMsg); free(errMsg); } int main (int argc, const char * argv[]) { const char *xsdPath = argv[1]; const char *xmlPath = argv[2]; printf("\n"); printf("XSD File: %s\n", xsdPath); printf("XML File: %s\n", xmlPath); int xmlLength = get_file_size(xmlPath); char *xmlSource = (char *)malloc(sizeof(char) * xmlLength); FILE *p = fopen(xmlPath, "r"); char c; unsigned int i = 0; while ((c = fgetc(p)) != EOF) { xmlSource[i++] = c; } printf("\n"); printf("XML Source:\n\n%s\n", xmlSource); fclose(p); printf("\n"); int result = 42; xmlSchemaParserCtxtPtr parserCtxt = NULL; xmlSchemaPtr schema = NULL; xmlSchemaValidCtxtPtr validCtxt = NULL; xmlDocPtr xmlDocumentPointer = xmlParseMemory(xmlSource, xmlLength); parserCtxt = xmlSchemaNewParserCtxt(xsdPath); if (parserCtxt == NULL) { fprintf(stderr, "Could not create XSD schema parsing context.\n"); goto leave; } schema = xmlSchemaParse(parserCtxt); if (schema == NULL) { fprintf(stderr, "Could not parse XSD schema.\n"); goto leave; } validCtxt = xmlSchemaNewValidCtxt(schema); if (!validCtxt) { fprintf(stderr, "Could not create XSD schema validation context.\n"); goto leave; } xmlSetStructuredErrorFunc(NULL, NULL); xmlSetGenericErrorFunc(NULL, handleValidationError); xmlThrDefSetStructuredErrorFunc(NULL, NULL); xmlThrDefSetGenericErrorFunc(NULL, handleValidationError); result = xmlSchemaValidateDoc(validCtxt, xmlDocumentPointer); leave: if (parserCtxt) { xmlSchemaFreeParserCtxt(parserCtxt); } if (schema) { xmlSchemaFree(schema); } if (validCtxt) { xmlSchemaFreeValidCtxt(validCtxt); } printf("\n"); printf("Validation successful: %s (result: %d)\n", (result == 0) ? "YES" : "NO", result); return 0; } console output: XSD File: /Users/dephiniteloop/Desktop/xml_validate/schema.xsd XML File: /Users/dephiniteloop/Desktop/xml_validate/test.gkml XML Source: <?xml version="1.0" encoding="UTF-8"?> <foo xmlns="http://example.com/XMLSchema/1.0"> </foo> Validation Error: Element '{http://example.com/XMLSchema/1.0}foo': No matching global declaration available for the validation root. Validation successful: NO (result: 1845) In case it matters: I'm on OSX 10.6.7 with its default libxml2.dylib (/Developer/SDKs/MacOSX10.6.sdk/usr/lib/libxml2.2.7.3.dylib)

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  • printf field width : bytes or chars?

    - by leonbloy
    The printf/fprintf/sprintf family supports a width field in its format specifier. I have a doubt for the case of (non-wide) char arrays arguments: Is the width field supposed to mean bytes or characters? What is the (correct-de facto) behaviour if the char array corresponds to (say) a raw UTF-8 string? (I know that normally I should use some wide char type, that's not the point) For example, in char s[] = "ni\xc3\xb1o"; // utf8 encoded "niño" fprintf(f,"%5s",s); Is that function supposed to try to ouput just 5 bytes (plain C chars) (and you take responsability of misalignments or other problems if two bytes results in a textual characters) ? Or is it supposed to try to compute the length of "textual characters" of the array? (decodifying it... according to the current locale?) (in the example, this would amount to find out that the string has 4 unicode chars, so it would add a space for padding).

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  • best practice on precedence of variable declaration and error handling in C

    - by guest
    is there an advantage in one of the following two approaches over the other? here it is first tested, whether fopen succeeds at all and then all the variable declarations take place, to ensure they are not carried out, since they mustn't have had to void func(void) { FILE *fd; if ((fd = fopen("blafoo", "+r")) == NULL ) { fprintf(stderr, "fopen() failed\n"); exit(EXIT_FAILURE); } int a, b, c; float d, e, f; /* variable declarations */ /* remaining code */ } this is just the opposite. all variable declarations take place, even if fopen fails void func(void) { FILE *fd; int a, b, c; float d, e, f; /* variable declarations */ if ((fd = fopen("blafoo", "+r")) == NULL ) { fprintf(stderr, "fopen() failed\n"); exit(EXIT_FAILURE); } /* remaining code */ } does the second approach produce any additional cost, when fopen fails? would love to hear your thoughts!

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  • Can't find mistake -- 'segmentation fault' - in C

    - by Mosh
    Hello all! I wrote this function but can't get on the problem that gives me 'segmentation fault' msg. Thank you for any help guys !! /*This function extract all header files in a *.c1 file*/ void includes_extractor(FILE *c1_fp, char *c1_file_name ,int c1_file_str_len ) { int i=0; FILE *c2_fp , *header_fp; char ch, *c2_file_name,header_name[80]; /* we can assume line length 80 chars MAX*/ char inc_name[]="include"; char inc_chk[INCLUDE_LEN+1]; /*INCLUDE_LEN is defined | +1 for null*/ /* making the c2 file name */ c2_file_name=(char *) malloc ((c1_file_str_len)*sizeof(char)); if (c2_file_name == NULL) { printf("Out of memory !\n"); exit(0); } strcpy(c2_file_name , c1_file_name); c2_file_name[c1_file_str_len-1] = '\0'; c2_file_name[c1_file_str_len-2] = '2'; /*Open source & destination files + ERR check */ if( !(c1_fp = fopen (c1_file_name,"r") ) ) { fprintf(stderr,"\ncannot open *.c1 file !\n"); exit(0); } if( !(c2_fp = fopen (c2_file_name,"w+") ) ) { fprintf(stderr,"\ncannot open *.c2 file !\n"); exit(0); } /*next code lines are copy char by char from c1 to c2, but if meet header file, copy its content */ ch=fgetc(c1_fp); while (!feof(c1_fp)) { i=0; /*zero i */ if (ch == '#') /*potential #include case*/ { fgets(inc_chk, INCLUDE_LEN+1, c1_fp); /*8 places for "include" + null*/ if(strcmp(inc_chk,inc_name)==0) /*case #include*/ { ch=fgetc(c1_fp); while(ch==' ') /* stop when head with a '<' or '"' */ { ch=fgetc(c1_fp); } /*while(2)*/ ch=fgetc(c1_fp); /*start read header file name*/ while((ch!='"') || (ch!='>')) /*until we get the end of header name*/ { header_name[i] = ch; i++; ch=fgetc(c1_fp); }/*while(3)*/ header_name[i]='\0'; /*close the header_name array*/ if( !(header_fp = fopen (header_name,"r") ) ) /*open *.h for read + ERR chk*/ { fprintf(stderr,"cannot open header file !\n"); exit(0); } while (!feof(header_fp)) /*copy header file content to *.c2 file*/ { ch=fgetc(header_fp); fputc(ch,c2_fp); }/*while(4)*/ fclose(header_fp); } }/*frst if*/ else { fputc(ch,c2_fp); } ch=fgetc(c1_fp); }/*while(1)*/ fclose(c1_fp); fclose(c2_fp); free (c2_file_name); }

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  • sequential mandelbrot image creation

    - by visanio_learner
    can anyone tell me what is wrong in this code? i am getting an error in the main function, when i am calling the 'file_write' method function inside the main function, it says 'y' is not declared in this scope, but actually it was an argument that i have passed it in the method function earlier. is it a serious error? #include <stdio.h> #include <stdlib.h> #include <time.h> unsigned int width = 1500; unsigned int height = 1500; unsigned int max_iterations = 30000; unsigned int **color = NULL; double threshold = 4; double min_re = -2.0; double max_re = 1.0; double min_im = -1.2; double max_im = min_im+(max_re-min_re)*height/width; double x_factor = (max_re-min_re)/(width-1); double y_factor = (max_im-min_im)/(height-1); int file_write(int x, int y, double min_re, double max_im, double x_factor, double y_factor) { FILE *fractal = fopen("mandelbrot_imageSequential.ppm","w+"); if(fractal != NULL) { fprintf(fractal,"P6\n"); fprintf(fractal,"# %s\n", "Mandelbrot_imageSequential.ppm"); fprintf(fractal,"%d %d\n", height, width); fprintf(fractal,"255\n"); unsigned int R = 0, G = 0, B = 0; for(unsigned y = 0; y < height; ++y) { double c_im = max_im - y*y_factor; for(unsigned x = 0; x < width; ++x) { double c_re = min_re + x*x_factor; double Z_re = c_re, Z_im = c_im; bool image_inside = true; R = 0, G = 0, B = 0; for(unsigned n=0; n<max_iterations; ++n) { double Z_re2 = Z_re*Z_re, Z_im2 = Z_im*Z_im; if(Z_re2 + Z_im2 > threshold) { image_inside = false; G = n; if(G == 10) { G = 25, R = 10, B = 5; } break; } Z_im = 2 * Z_re * Z_im + c_im; Z_re = Z_re2 - Z_im2 + c_re; } if(image_inside) { putc(R, fractal); putc(G, fractal); putc(B, fractal); } else { putc(R, fractal); putc(G, fractal); putc(B, fractal); } } } fclose(fractal); return 0; } } int main(int argc, char *argv[]) { if(argc != 9) { printf("There is an error in the input given.\n"); return 0; } else { height = atoi(argv[1]); width = atoi(argv[2]); max_iterations = atoi(argv[3]); min_re = atof(argv[4]); max_re = atof(argv[5]); min_im = atof(argv[6]); max_im = atof(argv[7]); threshold = atoi(argv[8]); } color = (unsigned int**)malloc(height*sizeof(unsigned int*)); printf("height = %d\twidth = %d\tmaximum_iterations = %d\tminimum_x-value = %.2f\tmaximum_x-value = %.2f\tminimum_y-value = %.2f\tmaximum_y-value = %.2f\tthreshold_value = %.2f\t\n",height,width,max_iterations,min_re,max_re,min_im,max_im,threshold); int x; for(x = 0; x < height; x++) { color[x] = (unsigned int*)malloc(width*sizeof(unsigned int)); } time_t ts,te; time(&ts); file_write(x,y,min_re,max_im,x_factor,y_factor); time(&te); double diff = difftime(te,ts); printf("Total Time elapsed: %f\n",diff); for(x = 0; x < height; x++) { free(color[x]); } free(color); return 0; }

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  • Receiving broadcast packets using packet socket

    - by user314336
    Hello I try to send DHCP RENEW packets to the network and receive the responses. I broadcast the packet and I can see that it's successfully sent using Wireshark. But I have difficulties receiving the responses.I use packet sockets to catch the packets. I can see that there are responses to my RENEW packet using Wireshark, but my function 'packet_receive_renew' sometimes catch the packets but sometimes it can not catch the packets. I set the file descriptor using FDSET but the 'select' in my code can not realize that there are new packets for that file descriptor and timeout occurs. I couldn't make it clear that why it sometimes catches the packets and sometimes doesn't. Anybody have an idea? Thanks in advance. Here's the receive function. int packet_receive_renew(struct client_info* info) { int fd; struct sockaddr_ll sock, si_other; struct sockaddr_in si_me; fd_set rfds; struct timeval tv; time_t start, end; int bcast = 1; int ret = 0, try = 0; char buf[1500] = {'\0'}; uint8_t tmp[BUFLEN] = {'\0'}; struct dhcp_packet pkt; socklen_t slen = sizeof(si_other); struct dhcps* new_dhcps; memset((char *) &si_me, 0, sizeof(si_me)); memset((char *) &si_other, 0, sizeof(si_other)); memset(&pkt, 0, sizeof(struct dhcp_packet)); define SERVER_AND_CLIENT_PORTS ((67 << 16) + 68) static const struct sock_filter filter_instr[] = { /* check for udp */ BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9), BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 4), /* L5, L1, is UDP? */ /* skip IP header */ BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0), /* L5: */ /* check udp source and destination ports */ BPF_STMT(BPF_LD|BPF_W|BPF_IND, 0), BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, SERVER_AND_CLIENT_PORTS, 0, 1), /* L3, L4 */ /* returns */ BPF_STMT(BPF_RET|BPF_K, 0x0fffffff ), /* L3: pass */ BPF_STMT(BPF_RET|BPF_K, 0), /* L4: reject */ }; static const struct sock_fprog filter_prog = { .len = sizeof(filter_instr) / sizeof(filter_instr[0]), /* casting const away: */ .filter = (struct sock_filter *) filter_instr, }; printf("opening raw socket on ifindex %d\n", info->interf.if_index); if (-1==(fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP)))) { perror("packet_receive_renew::socket"); return -1; } printf("got raw socket fd %d\n", fd); /* Use only if standard ports are in use */ /* Ignoring error (kernel may lack support for this) */ if (-1==setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog, sizeof(filter_prog))) perror("packet_receive_renew::setsockopt"); sock.sll_family = AF_PACKET; sock.sll_protocol = htons(ETH_P_IP); //sock.sll_pkttype = PACKET_BROADCAST; sock.sll_ifindex = info->interf.if_index; if (-1 == bind(fd, (struct sockaddr *) &sock, sizeof(sock))) { perror("packet_receive_renew::bind"); close(fd); return -3; } if (-1 == setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &bcast, sizeof(bcast))) { perror("packet_receive_renew::setsockopt"); close(fd); return -1; } FD_ZERO(&rfds); FD_SET(fd, &rfds); tv.tv_sec = TIMEOUT; tv.tv_usec = 0; ret = time(&start); if (-1 == ret) { perror("packet_receive_renew::time"); close(fd); return -1; } while(1) { ret = select(fd + 1, &rfds, NULL, NULL, &tv); time(&end); if (TOTAL_PENDING <= (end - start)) { fprintf(stderr, "End receiving\n"); break; } if (-1 == ret) { perror("packet_receive_renew::select"); close(fd); return -4; } else if (ret) { new_dhcps = (struct dhcps*)calloc(1, sizeof(struct dhcps)); if (-1 == recvfrom(fd, buf, 1500, 0, (struct sockaddr*)&si_other, &slen)) { perror("packet_receive_renew::recvfrom"); close(fd); return -4; } deref_packet((unsigned char*)buf, &pkt, info); if (-1!=(ret=get_option_val(pkt.options, DHO_DHCP_SERVER_IDENTIFIER, tmp))) { sprintf((char*)tmp, "%d.%d.%d.%d", tmp[0],tmp[1],tmp[2],tmp[3]); fprintf(stderr, "Received renew from %s\n", tmp); } else { fprintf(stderr, "Couldnt get DHO_DHCP_SERVER_IDENTIFIER%s\n", tmp); close(fd); return -5; } new_dhcps->dhcps_addr = strdup((char*)tmp); //add to list if (info->dhcps_list) info->dhcps_list->next = new_dhcps; else info->dhcps_list = new_dhcps; new_dhcps->next = NULL; } else { try++; tv.tv_sec = TOTAL_PENDING - try * TIMEOUT; tv.tv_usec = 0; fprintf(stderr, "Timeout occured\n"); } } close(fd); printf("close fd:%d\n", fd); return 0; }

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