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  • Why my shell program wont open the file got as argument in function "cat"

    - by anna karenina
    I included the code below, sorry to bother you with so much code. Argument parsing is ok, i checked it out with watches. I've put some printfs to check out where the problem may be and it seems that it wont open the file cat receives as argument. i called from shell like "cat -b file" #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <string.h> #define TRUE 0 #define FALSE 1 void yes(int argc, char *argv[]); int cat(int argc, char *argv[]); //#include "cat.h" //#include "yes.h" //#include"tee.h" char buf[50],c[10], *p2,*p, *pch; int count; char *matrix[20]; void yes(int argc, char *argv[]) { int i; // if (argc >= 2 && *argv[1] == '-') // { //printf("ERROR!"); //} //if (argc == 1) // { while (1) if (puts("y") == EOF) { perror("yes"); exit(FALSE); } // } while (1) for (i = 1; i < argc; i++) if (fputs(argv[i], stdout) == EOF || putchar(i == argc - 1 ? '\n' : ' ') == EOF) { perror("yes"); exit(FALSE); } //exit(TRUE); } int main(int argc, char *argv[]) { //p=(char *)malloc(sizeof(char)*50); do { fprintf (stderr, "$ "); fgets (buf,50,stdin); p=buf; fprintf (stderr, "Comanda primita de la tastatura: "); fputs (buf, stderr); int i=0,j=0; //strcpy(p,buf); strcpy(c,"\0"); while (buf[i] == ' ') { i++; p++; } if (buf[i] == '#') fprintf (stderr, "Nici o comanda, ci e un comentariu!\n"); else { j=0; while (buf[i] != ' ' && buf[i] != '\n') { i++; j++; } strncpy (c,p,j); fprintf (stderr, "%s\n",c); if (strcmp (c,"yes") == 0) { p2 = p+j+1; pch = strtok (p2," "); count = 0; while (pch != NULL) { //printf ("%s\n",pch); matrix[count] = strdup(pch); pch = strtok (NULL, " "); count++; } yes(count, matrix); fprintf (stderr, "Aici se va executa comanda yes\n"); } else if (strcmp (c,"cat") == 0) { p2 = p+j+1; pch = strtok (p2," "); count = 0; while (pch != NULL) { //printf ("%s\n",pch); matrix[count] = strdup(pch); pch = strtok (NULL, " "); count++; } cat(count,matrix); fprintf (stderr, "Aici se va executa comanda cat \n"); } else if (strcmp (c,"tee") == 0) { //tee(); fprintf(stderr, "Aici se va executa comanda tee\n"); } fprintf (stderr, "Aici se va executa comanda basename\n"); strcpy(buf,"\0"); } } while (strcmp(c, "exit") != 0); fprintf (stderr, "Terminat corect!\n"); return 0; } int cat(int argc, char *argv[]) { int c ; opterr = 0 ; optind = 0 ; char number = 0; char squeeze = 0; char marker = 0; fprintf(stderr,"SALUT< SUNT IN FUNCTIZE>\n"); while ((c = getopt (argc, argv, "bnsE")) != -1) switch (c) { case 'b' : number = 1; break; case 'n' : number = 2; break; case 'm' : marker = 1; break; case 's' : squeeze = 1; break; case 'E' : marker = 1; break; } if (optind + 1 != argc) { fprintf (stderr, "\tWrong arguments!\n") ; return -1 ; } FILE * fd = fopen (argv[optind], "r"); printf("am deschis fisierul %s ",argv[optind]); if (fd == NULL) { printf("FISIER NULL asdasdasdasdasd"); return 1; } char line[1025]; int line_count = 1; while (!feof(fd)) { fgets(line, 1025, fd); printf("sunt in while :> %s",line); int len = strlen(line); if (line[len - 1] == '\n') { if(len - 2 >= 0) { if(line[len - 2] == '\r') { line[len - 2] = '\0'; len -= 2; } else { line[len - 1] = '\0'; len -= 1; } } else { line[len - 1] = '\0'; len -= 1; } } if (squeeze == 1 && len == 0) continue; if (number == 1) { fprintf (stdout, "%4d ", line_count); line_count++; } else if (number == 2) { if (len > 0) { fprintf (stdout, "%4d ", line_count); line_count++; } else fprintf (stdout, " "); } fprintf(stdout, "%s", line); if (marker == 1) fprintf(stdout, "$"); fprintf(stdout, "\n"); } fclose (fd); return 0 ; }

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  • QT:QString to char conversion

    - by mawia
    hi! all, I was tryin to convert a QSting to char* type but by following methods,but those does'nt seem to work. // QLineEdit *line=new QLineEdit();{just to describe what is line here} QString temp=line->text(); char *str=(char *)malloc(10); QByteArray ba=temp.toLatin1(); strcpy(str,ba.data()); can you elobrate the possible flaw with this method ,or tell alternative method.

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  • Basic shared memory program in C

    - by nicopuri
    Hi, I want to make a basic chat application in C using Shared memory. I am working in Linux. The application consist in writing the client and the server can read, and if the server write the client can read the message. I tried to do this, but I can't achieve the communication between client and server. The code is the following: Server.c int main(int argc, char **argv) { char *msg; static char buf[SIZE]; int n; msg = getmem(); memset(msg, 0, SIZE); initmutex(); while ( true ) { if( (n = read(0, buf, sizeof buf)) 0 ) { enter(); sprintf(msg, "%.*s", n, buf); printf("Servidor escribe: %s", msg); leave(); }else{ enter(); if ( strcmp(buf, msg) ) { printf("Servidor lee: %s", msg); strcpy(buf, msg); } leave(); sleep(1); } } return 0; } Client.c int main(int argc, char **argv) { char *msg; static char buf[SIZE-1]; int n; msg = getmem(); initmutex(); while(true) { if ( (n = read(0, buf, sizeof buf)) 0 ) { enter(); sprintf(msg, "%.*s", n, buf); printf("Cliente escribe: %s", msg); leave(); }else{ enter(); if ( strcmp(buf, msg) ) { printf("Cliente lee: %s", msg); strcpy(buf, msg); } leave(); sleep(1); } } printf("Cliente termina\n"); return 0; } The shared memory module is the folowing: #include "common.h" void fatal(char *s) { perror(s); exit(1); } char * getmem(void) { int fd; char *mem; if ( (fd = shm_open("/message", O_RDWR|O_CREAT, 0666)) == -1 ) fatal("sh_open"); ftruncate(fd, SIZE); if ( !(mem = mmap(NULL, SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0)) ) fatal("mmap"); close(fd); return mem; } static sem_t *sd; void initmutex(void) { if ( !(sd = sem_open("/mutex", O_RDWR|O_CREAT, 0666, 1)) ) fatal("sem_open"); } void enter(void) { sem_wait(sd); } void leave(void) { sem_post(sd); }

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  • How to create a simple Proxy to access web servers in C

    - by jesusiniesta
    Hi. I’m trying to create an small Web Proxy in C. First, I’m trying to get a webpage, sending a GET frame to the server. I don’t know what I have missed, but I am not receiving any response. I would really appreciate if you can help me to find what is missing in this code. int main (int argc, char** argv) { int cache_size, //size of the cache in KiB port, port_google = 80, dir, mySocket, socket_google; char google[] = "www.google.es", ip[16]; struct sockaddr_in socketAddr; char buffer[10000000]; if (GetParameters(argc,argv,&cache_size,&port) != 0) return -1; GetIP (google, ip); printf("ip2 = %s\n",ip); dir = inet_addr (ip); printf("ip3 = %i\n",dir); /* Creation of a socket with Google */ socket_google = conectClient (port_google, dir, &socketAddr); if (socket_google < 0) return -1; else printf("Socket created\n"); sprintf(buffer,"GET /index.html HTTP/1.1\r\n\r\n"); if (write(socket_google, (void*)buffer, LONGITUD_MSJ+1) < 0 ) return 1; else printf("GET frame sent\n"); strcpy(buffer,"\n"); read(socket_google, buffer, sizeof(buffer)); // strcpy(message,buffer); printf("%s\n", buffer); return 0; } And this is the code I use to create the socket. I think this part is OK, but I copy it just in case. int conectClient (int puerto, int direccion, struct sockaddr_in *socketAddr) { int mySocket; char error[1000]; if ( (mySocket = socket(AF_INET, SOCK_STREAM, 0)) == -1) { printf("Error when creating the socket\n"); return -2; } socketAddr->sin_family = AF_INET; socketAddr->sin_addr.s_addr = direccion; socketAddr->sin_port = htons(puerto); if (connect (mySocket, (struct sockaddr *)socketAddr,sizeof (*socketAddr)) == -1) { snprintf(error, sizeof(error), "Error in %s:%d\n", __FILE__, __LINE__); perror(error); printf("%s\n",error); printf ("-- Error when stablishing a connection\n"); return -1; } return mySocket; } Thanks!

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  • C++ segmentation error when first parameter is null in comparison operator overload

    - by user1774515
    I am writing a class called Word, that handles a c string and overloads the <, , <=, = operators. word.h: friend bool operator<(const Word &a, const Word &b); word.cc: bool operator<(const Word &a, const Word &b) { if(a == NULL && b == NULL) return false; if(a == NULL) return true; if(b == NULL) return false; return a.wd < b.wd; //wd is a valid c string } main: char* temp = NULL; //EDIT: i was mistaken, temp is a char pointer Word a("blah"); //a.wd = [b,l,a,h] cout << (temp<a); i get a segmentation error before the first line of the operator< method after the last line in the main. I can correct the problem by writing cout << (a>temp); where the operator> is similarly defined and i get no errors. but my assignment requires (temp < a) to work so this is where i ask for help. EDIT: i made a mistake the first time and i said temp was of type Word, but it is actually of type char*. so i assume that the compiler converts temp to a Word using one of my constructors. i dont know which one it would use and why this would work since the first parameter is not Word. here is the constructor i think is being used to make the Word using temp: Word::Word(char* c, char* delimeters=NULL) { char *temporary = "\0"; if(c == NULL) c = temporary; check(stoppers!=NULL, "(Word(char*,char*))NULL pointer"); //exits the program if the expression is false if(strlen(c) == 0) size = DEFAULT_SIZE; //10 else size = strlen(c) + 1 + DEFAULT_SIZE; wd = new char[size]; check(wd!=NULL, "Word(char*,char*))heap overflow"); delimiters = new char[strlen(stoppers) + 1]; //EDIT: changed to [] check(delimiters!=NULL,"Word(char*,char*))heap overflow"); strcpy(wd,c); strcpy(delimiters,stoppers); count = strlen(wd); } wd is of type char* thanks for looking at this big question and trying to help. let me know if you need more code to look at

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  • Accessing char* after assigning its value C

    - by iSight
    Hi, I have assign the value of a member variable as under: myValue = (char*)malloc(strlen(inValue) * sizeof(char)); strcpy(mValue, inValue); while assigning it the value was proper as(taking printf output): http://www.w3.org/2001/XMLSchema But, when i get its value after wards i get it as: http://www.w3.org/2001/XMLSchema(! What could be the problem for this issue

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  • storing characters in char data type C language

    - by iSight
    Hi, I can store string of few length in char data type. But when it exceeds its capacity what can be the alternative way to store string. I am using char data type. void setString(char* inPoints) { if (strcmp(mPoints, inPoints)!= ZERO) { if (mPoints) { free(mPoints); } mPoints = (char*)malloc((strlen(inPoints) + 1) * sizeof(char)); strcpy(mPoints, inPoints); } }

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  • Library like ENet, but for TCP?

    - by Milo
    I'm not looking to use boost::asio, it is overly complex for my needs. I'm building a game that is cross platform, for desktop, iPhone and Android. I found a library called ENet which is pretty much what I need, but it uses UDP which does not seem to support encryption and a few other things. Given that the game is an event driven card game, TCP seems like the right fit. However, all I have found is WINSOCK / berkley sockets and bost::asio. Here is a sample client server application with ENet: #include <enet/enet.h> #include <stdlib.h> #include <string> #include <iostream> class Host { ENetAddress address; ENetHost * server; ENetHost* client; ENetEvent event; public: Host() :server(NULL) { enet_initialize(); setupServer(); } void setupServer() { if(server) { enet_host_destroy(server); server = NULL; } address.host = ENET_HOST_ANY; /* Bind the server to port 1234. */ address.port = 1721; server = enet_host_create (& address /* the address to bind the server host to */, 32 /* allow up to 32 clients and/or outgoing connections */, 2 /* allow up to 2 channels to be used, 0 and 1 */, 0 /* assume any amount of incoming bandwidth */, 0 /* assume any amount of outgoing bandwidth */); } void daLoop() { while(true) { /* Wait up to 1000 milliseconds for an event. */ while (enet_host_service (server, & event, 5000) > 0) { ENetPacket * packet; switch (event.type) { case ENET_EVENT_TYPE_CONNECT: printf ("A new client connected from %x:%u.\n", event.peer -> address.host, event.peer -> address.port); /* Store any relevant client information here. */ event.peer -> data = "Client information"; /* Create a reliable packet of size 7 containing "packet\0" */ packet = enet_packet_create ("packet", strlen ("packet") + 1, ENET_PACKET_FLAG_RELIABLE); /* Extend the packet so and append the string "foo", so it now */ /* contains "packetfoo\0" */ enet_packet_resize (packet, strlen ("packetfoo") + 1); strcpy ((char*)& packet -> data [strlen ("packet")], "foo"); /* Send the packet to the peer over channel id 0. */ /* One could also broadcast the packet by */ /* enet_host_broadcast (host, 0, packet); */ enet_peer_send (event.peer, 0, packet); /* One could just use enet_host_service() instead. */ enet_host_flush (server); break; case ENET_EVENT_TYPE_RECEIVE: printf ("A packet of length %u containing %s was received from %s on channel %u.\n", event.packet -> dataLength, event.packet -> data, event.peer -> data, event.channelID); /* Clean up the packet now that we're done using it. */ enet_packet_destroy (event.packet); break; case ENET_EVENT_TYPE_DISCONNECT: printf ("%s disconected.\n", event.peer -> data); /* Reset the peer's client information. */ event.peer -> data = NULL; } } } } ~Host() { if(server) { enet_host_destroy(server); server = NULL; } atexit (enet_deinitialize); } }; class Client { ENetAddress address; ENetEvent event; ENetPeer *peer; ENetHost* client; public: Client() :peer(NULL) { enet_initialize(); setupPeer(); } void setupPeer() { client = enet_host_create (NULL /* create a client host */, 1 /* only allow 1 outgoing connection */, 2 /* allow up 2 channels to be used, 0 and 1 */, 57600 / 8 /* 56K modem with 56 Kbps downstream bandwidth */, 14400 / 8 /* 56K modem with 14 Kbps upstream bandwidth */); if (client == NULL) { fprintf (stderr, "An error occurred while trying to create an ENet client host.\n"); exit (EXIT_FAILURE); } /* Connect to some.server.net:1234. */ enet_address_set_host (& address, "192.168.2.13"); address.port = 1721; /* Initiate the connection, allocating the two channels 0 and 1. */ peer = enet_host_connect (client, & address, 2, 0); if (peer == NULL) { fprintf (stderr, "No available peers for initiating an ENet connection.\n"); exit (EXIT_FAILURE); } /* Wait up to 5 seconds for the connection attempt to succeed. */ if (enet_host_service (client, & event, 20000) > 0 && event.type == ENET_EVENT_TYPE_CONNECT) { std::cout << "Connection to some.server.net:1234 succeeded." << std::endl; } else { /* Either the 5 seconds are up or a disconnect event was */ /* received. Reset the peer in the event the 5 seconds */ /* had run out without any significant event. */ enet_peer_reset (peer); puts ("Connection to some.server.net:1234 failed."); } } void daLoop() { ENetPacket* packet; /* Create a reliable packet of size 7 containing "packet\0" */ packet = enet_packet_create ("backet", strlen ("backet") + 1, ENET_PACKET_FLAG_RELIABLE); /* Extend the packet so and append the string "foo", so it now */ /* contains "packetfoo\0" */ enet_packet_resize (packet, strlen ("backetfoo") + 1); strcpy ((char*)& packet -> data [strlen ("backet")], "foo"); /* Send the packet to the peer over channel id 0. */ /* One could also broadcast the packet by */ /* enet_host_broadcast (host, 0, packet); */ enet_peer_send (event.peer, 0, packet); /* One could just use enet_host_service() instead. */ enet_host_flush (client); while(true) { /* Wait up to 1000 milliseconds for an event. */ while (enet_host_service (client, & event, 1000) > 0) { ENetPacket * packet; switch (event.type) { case ENET_EVENT_TYPE_RECEIVE: printf ("A packet of length %u containing %s was received from %s on channel %u.\n", event.packet -> dataLength, event.packet -> data, event.peer -> data, event.channelID); /* Clean up the packet now that we're done using it. */ enet_packet_destroy (event.packet); break; } } } } ~Client() { atexit (enet_deinitialize); } }; int main() { std::string a; std::cin >> a; if(a == "host") { Host host; host.daLoop(); } else { Client c; c.daLoop(); } return 0; } I looked at some socket tutorials and they seemed a bit too low level. I just need something that abstracts away the platform (eg, no WINSOCKS) and that has basic ability to keep track of connected clients and send them messages. Thanks

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  • Why are marketing employees, product managers, etc. deserving of their own office, yet programmers are jammed in a room as many as possible?

    - by TheImirOfGroofunkistan
    I don't understand why many (many) companies treat software developers like they are assembly line workers making widgets. Joel Spolsky has a great example of the problems this creates: With programmers, it's especially hard. Productivity depends on being able to juggle a lot of little details in short term memory all at once. Any kind of interruption can cause these details to come crashing down. When you resume work, you can't remember any of the details (like local variable names you were using, or where you were up to in implementing that search algorithm) and you have to keep looking these things up, which slows you down a lot until you get back up to speed. Here's the simple algebra. Let's say (as the evidence seems to suggest) that if we interrupt a programmer, even for a minute, we're really blowing away 15 minutes of productivity. For this example, lets put two programmers, Jeff and Mutt, in open cubicles next to each other in a standard Dilbert veal-fattening farm. Mutt can't remember the name of the Unicode version of the strcpy function. He could look it up, which takes 30 seconds, or he could ask Jeff, which takes 15 seconds. Since he's sitting right next to Jeff, he asks Jeff. Jeff gets distracted and loses 15 minutes of productivity (to save Mutt 15 seconds). Now let's move them into separate offices with walls and doors. Now when Mutt can't remember the name of that function, he could look it up, which still takes 30 seconds, or he could ask Jeff, which now takes 45 seconds and involves standing up (not an easy task given the average physical fitness of programmers!). So he looks it up. So now Mutt loses 30 seconds of productivity, but we save 15 minutes for Jeff. Ahhh! Quote Link More Spolsky on Offices Why don't managers and owner's see this?

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  • Why do marketing employees get their own office, yet programmers are jammed in a room as many as possible?

    - by TheImirOfGroofunkistan
    I don't understand why many (many) companies treat software developers like they are assembly line workers making widgets. Joel Spolsky has a great example of the problems this creates: With programmers, it's especially hard. Productivity depends on being able to juggle a lot of little details in short term memory all at once. Any kind of interruption can cause these details to come crashing down. When you resume work, you can't remember any of the details (like local variable names you were using, or where you were up to in implementing that search algorithm) and you have to keep looking these things up, which slows you down a lot until you get back up to speed. Here's the simple algebra. Let's say (as the evidence seems to suggest) that if we interrupt a programmer, even for a minute, we're really blowing away 15 minutes of productivity. For this example, lets put two programmers, Jeff and Mutt, in open cubicles next to each other in a standard Dilbert veal-fattening farm. Mutt can't remember the name of the Unicode version of the strcpy function. He could look it up, which takes 30 seconds, or he could ask Jeff, which takes 15 seconds. Since he's sitting right next to Jeff, he asks Jeff. Jeff gets distracted and loses 15 minutes of productivity (to save Mutt 15 seconds). Now let's move them into separate offices with walls and doors. Now when Mutt can't remember the name of that function, he could look it up, which still takes 30 seconds, or he could ask Jeff, which now takes 45 seconds and involves standing up (not an easy task given the average physical fitness of programmers!). So he looks it up. So now Mutt loses 30 seconds of productivity, but we save 15 minutes for Jeff. Ahhh! Quote Link More Spolsky on Offices Why don't managers and owner's see this?

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  • Simple C: atof giving wrong value [migrated]

    - by Doc
    I have a program that reads input from a singe line(string obviously) and organizes it into arrays. The problem I have is that at one point the program reads two different values and returns the first one twice. Initially I thought the program was reading the same value twice but when I tested it turned out that it got the correct one but is inputting the wrong one. for example Input: 2 0.90 0.75 0.7 0.65 sorry to snip it (while(fgets (string[test], sizeof(string[test]),ifp)) pch = strtok_r(NULL, " ", &prog); tem3 = atoi(pch); while (loop<tem3) { pch=strtok_r(NULL," ",&prog); venseatfloat[test][loop][DISCOUNT][OCCUPIED]=(float)atof(pch); printf("%f is discount\t",venseatfloat[test][loop][DISCOUNT][OCCUPIED]); pch=strtok_r(NULL, " ", &prog); strcpy(temp, pch); venseatfloat[test][loop][REGULAR][OCCUPIED]=(float)atof(pch); printf("%s is the string but %.3f is regular\n", temp ,venseatfloat[test][loop][DISCOUNT][OCCUPIED]); loop++; } output: >0.900000 is discount 0.75 is the string but 0.900 is regular >0.700000 is discount 0.65 is the string but 0.700 is regular What is going on?

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  • Pointers inside a structure [on hold]

    - by user3402552
    I have the next program: #include<stdio.h> #include<stdlib.h> struct a { char *ch; char *str; }; int main() { struct a s1; char ptr[100]; int m, n; printf("\n Enter a string : "); gets(ptr); m = strlen(ptr); s1.ch = (char *)malloc(strlen(ptr) * sizeof(char)); if(s1.ch) { strcpy(s1.ch, ptr); } else { printf("\n Alocation failed!\n"); } printf("\n %s\n\n", s1.ch); while(*s1.ch) { printf(" %c", *(s1.ch)); s1.ch++; } printf("\n\n"); s1.ch = s1.ch - m; printf("\n\n\n %s \n\n", s1.ch); } Is this ok this program in this way ? I mean the pointers should not be initialized ? And if it is not ok, why compile it without errors?

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  • How to fix legacy code that uses <string.h> unsafely?

    - by Snowbody
    We've got a bunch of legacy code, written in straight C (some of which is K&R!), which for many, many years has been compiled using Visual C 6.0 (circa 1998) on an XP machine. We realize this is unsustainable, and we're trying to move it to a modern compiler. Political issues have said that the most recent compiler allowed is VC++ 2005. When compiling the project, there are many warnings about the unsafe string manipulation functions used (sprintf(), strcpy(), etc). Reviewing some of these places shows that the code is indeed unsafe; it does not check for buffer overflows. The compiler warning recommends that we move to using sprintf_s(), strcpy_s(), etc. However, these are Microsoft-created (and proprietary) functions and aren't available on (say) gcc (although we're primarily a Windows shop we do have some clients on various flavors of *NIX) How ought we to proceed? I don't want to roll our own string libraries. I only want to go over the code once. I'd rather not switch to C++ if we can help it.

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  • calculater by using reverse polish notation and using a stack

    - by programmer
    hello everyone I have a segmentation fault ,can you help please? if i have this operater "3 5 +" that mean 3+5 and like "9 8 * 5 + 4 + sin", "sin(((9*8)+5)+4)" so my idea is check if the first and second are numbers and push theem in the stack then when i have operator i pop the numbers and make the calculation then push the answer again. ` typedef struct st_node { float val; struct st_node *next; } t_node; typedef t_node t_stack; // a function to allocate memory for a stack and returns the stack t_stack* fnewCell() { t_stack* ret; ret = (t_stack*) malloc(sizeof(t_stack)); return ret; } // a function to allocate memory for a stack, fills it with value v and pointer n , and returns the stack t_stack* fnewCellFilled(float v, t_stack* n) { t_stack* ret; ret = fnewCell(); ret->val = v; ret->next =n; return ret; } //function to initialize stack void initstack(t_stack** stack) { fnewCellFilled(0,NULL); } // add new cell void insrtHead(t_stack** head,float val) { *head = fnewCellFilled(val,*head); } //function to push the value v into the stack s void push(t_stack **s, float val) { insrtHead(s,val); } //function to pop a value from the stack and returns it int pop(t_stack **s) { t_stack* tmp; int ret; tmp = (*s)->next; ret = (*s)->val; free(*s); (*s) = tmp; return ret; } int isempty (t_stack *t) { return t == NULL; } //function to transfer a string(str) to int (value) //returns -1 when success , i otherwise int str2int(char *str,int *value) { int i; *value = 0; int sign=(str[0]=='-' ? -1 : 1); for(i=(str[0]=='-' ? 1 : 0);str[i]!=0;i++) { if(!(str[i]>=48 && str[i]<=57)) // Ascii char 0 to 9 return i; *value= *value*10+(str[i]-48); } *value = *value * sign; return -1; } //a function that takes a string, transfer it into integer and make operation using a stack void function(t_stack *stack, char *str) { char x[10]=" "; int y,j,i=0,z; printf("++\n"); if(str[i] != '\0') { strcpy(x, strtok(str, " ")); z= str2int(x, &y); if(z == -1) { push(&stack,y); i=i+2; } } while(str[i] != '\0') { strcpy(x, strtok(NULL, " ")); z= str2int(x, &y); if(z == -1) { printf("yes %d",y); push(&stack,y); i=i+2; } else { y=pop(&stack); j=pop(&stack); if(x[0] == '+' ) push(&stack,y+j); else if (x[0] == '-' ) push(&stack,j-y); else if(x[0] == '*' ) push(&stack,j*y); else if(x[0] == '/') push (&stack ,j/y); } } } int main() { t_stack *s; initstack(&s); char *str="3 5 +"; function(s,str); return 0; } `

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  • Problems manipulating strings through a stdcall to a dll

    - by ibiza
    I need to create a C++ dll that will be called from another program through stdcall. What is needed : the caller program will pass an array of string to the dll and the dll should change the string values in the array. The caller program will then continue to work with these string values that came from the dll. I made a simple test project and I am obviously missing something... Here is my test C++ dll : #ifndef _DLL_H_ #define _DLL_H_ #include <string> #include <iostream> struct strStruct { int len; char* string; }; __declspec (dllexport) int __stdcall TestFunction(strStruct* s) { std::cout << "Just got in dll" << std::endl; std::cout << s[0].string << std::endl; //////std::cout << s[1].string << std::endl; /* char str1[] = "foo"; strcpy(s[0].string, str1); s[0].len = 3; char str2[] = "foobar"; strcpy(s[1].string, str2); s[1].len = 6; */ //std::cout << s[0].string << std::endl; //std::cout << s[1].string << std::endl; std::cout << "Getting out of dll" << std::endl; return 1; } #endif and here is a simple C# program that I am using to test my test dll : using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.InteropServices; namespace TestStr { class Program { [DllImport("TestStrLib.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.StdCall)] public static extern int TestFunction(string[] s); static void Main(string[] args) { string[] test = new string[2] { "a1a1a1a1a1", "b2b2b2b2b2" }; Console.WriteLine(test[0]); Console.WriteLine(test[1]); TestFunction(test); Console.WriteLine(test[0]); Console.WriteLine(test[1]); Console.ReadLine(); } } } And here is the output produced : a1a1a1a1a1 b2b2b2b2b2 Just got in dll b2b2b2b2b2 Getting out of dll a1a1a1a1a1 b2b2b2b2b2 I have some questions : 1) Why is it outputting the element in the second position of the array rather than in the first position?? 2) If I uncomment the line commented with ////// in the dll file, the program crashes. Why? 3) Obviously I wanted to do more things in the dll (the parts in /* */) than what it does right now, but I am blocked by the first 2 questions... Thanks for all your help

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  • Recursively created linked lists with a class, C++

    - by Jon Brant
    I'm using C++ to recursively make a hexagonal grid (using a multiply linked list style). I've got it set up to create neighboring tiles easily, but because I'm doing it recursively, I can only really create all 6 neighbors for a given tile. Obviously, this is causing duplicate tiles to be created and I'm trying to get rid of them in some way. Because I'm using a class, checking for null pointers doesn't seem to work. It's either failing to convert from my Tile class to and int, or somehow converting it but not doing it properly. I'm explicitly setting all pointers to NULL upon creation, and when I check to see if it still is, it says it's not even though I never touched it since initialization. Is there a specific way I'm supposed to do this? I can't even traverse the grid without NULLs of some kind Here's some of my relevant code. Yes, I know it's embarassing. Tile class header: class Tile { public: Tile(void); Tile(char *Filename); ~Tile(void); void show(void); bool LoadGLTextures(); void makeDisplayList(); void BindTexture(); void setFilename(char *newName); char Filename[100]; GLuint texture[2]; GLuint displayList; Tile *neighbor[6]; float xPos, yPos,zPos; };` Tile Initialization: Tile::Tile(void) { xPos=0.0f; yPos=0.0f; zPos=0.0f; glEnable(GL_DEPTH_TEST); strcpy(Filename, strcpy(Filename, "Data/BlueTile.bmp")); if(!BuildTexture(Filename, texture[0]))MessageBox(NULL,"Texture failed to load!","Crap!",MB_OK|MB_ICONASTERISK); for(int x=0;x<6;x++) { neighbor[x]=NULL; } } Creation of neighboring tiles: void MakeNeighbors(Tile *InputTile, int stacks) { for(int x=0;x<6;x++) { InputTile->neighbor[x]=new Tile();InputTile->neighbor[x]->xPos=0.0f;InputTile->neighbor[x]->yPos=0.0f;InputTile->zPos=float(stacks); } if(stacks) { for(int x=0;x<6;x++)MakeNeighbors(InputTile->neighbor[x],stacks-1); } } And finally, traversing the grid: void TraverseGrid(Tile *inputTile) { Tile *temp; for(int x=0;x<6;x++) if(inputTile->neighbor[x]) { temp=inputTile->neighbor[x]; temp->xPos=0.0f; TraverseGrid(temp); //MessageBox(NULL,"Not Null!","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION); } } The key line is "if(inputTile-neighbor[x])" and whether I make it "if(inputTile-neighbor[x]==NULL)" or whatever I do, it just isn't handling it properly. Oh and I'm also aware that I haven't set up the list fully. It's only one direction now.

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  • where is the error in this C code , and how to get rid of the warnings?

    - by mekasperasky
    #include<stdio.h> #include<string.h> //This program is a sorting application that reads a sequence of numbers from a file and prints them on the screen . The reading from the file here , is a call back function . typedef int (*CompFunc)(const char* , const char* ); typedef int (*ReadCheck)(char nullcheck); char array[100]; //Let this fucntion be done in the library itself . It doesnt care as to where the compare function and how is it implemented . Meaning suppose the function wants to do sort in ascending order or in descending order then the changes have to be done by the client code in the "COMPARE" function who will be implementing the lib code . void ReadFile(FILE *fp,ReadCheck rc) { char a; char d[100]; int count = 0,count1=0; a=fgetc(fp); while(1 != (*rc)(a)) { if(a=='\0') { strcpy(array[count],d); count=count+1; } else { d[count1]=a; count1=count1+1; } } } void Bubblesort(int* array , int size , int elem_size , CompFunc cf) { int i,j; int *temp; for( i=0;i < size ;i++) { for ( j=0;j < size -1 ; j++) { // make the callback to the comparision function if(1 == (*cf)(array+j*elem_size,array+ (j+1)*elem_size)) { //interchanging of elements temp = malloc(sizeof(int *) * elem_size); memcpy(temp , array+j*elem_size,elem_size); memcpy(array+j*elem_size,array+(j+1)*elem_size,elem_size); memcpy(array + (j+1)*elem_size , temp , elem_size); free(temp); } } } } //Let these functions be done at the client side int Compare(const char* el1 , const char* el2) { int element1 = *(int*)el1; int element2 = *(int*)el2; if(element1 < element2 ) return -1; if(element1 > element2) return 1 ; return 0; } int ReadChecked(char nullcheck) { if (nullcheck=='\n') return 1; else return 0; } int main() { FILE fp1; int k; fp1=fopen("readdata.txt","r"); Readfile(fp1,&ReadChecked); Bubblesort((char*)array,5,sizeof(array[0]),&Compare); printf("after sorting \n"); for (k=0;k<5;k++) printf("%d",array[k]); return 0; } The error i get is fsc1.c: In function ‘ReadFile’: fsc1.c:19: warning: passing argument 1 of ‘strcpy’ makes pointer from integer without a cast fsc1.c: In function ‘Bubblesort’: fsc1.c:40: warning: passing argument 1 of ‘cf’ from incompatible pointer type fsc1.c:40: warning: passing argument 2 of ‘cf’ from incompatible pointer type fsc1.c:43: warning: incompatible implicit declaration of built-in function ‘malloc’ fsc1.c:47: warning: incompatible implicit declaration of built-in function ‘free’ fsc1.c: In function ‘main’: fsc1.c:80: error: incompatible types in assignment fsc1.c:82: warning: passing argument 1 of ‘Bubblesort’ from incompatible pointer type

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  • How to find an element in an array in C

    - by gkaykck
    I am trying to find the location of an element in the array. I have tried to use this code i generated for(i=0;i<10;i++) { if (strcmp(temp[0],varptr[i])==0) j=i; } varptr is a pointer which points to array var[11][10] and it is by the definition *varptr[11][10]. I have assigned strings to var[i] and i want to get the "i" number of my element NOT THE ADRESS. Thanks for any comment. EDit: temp is also a pointer which points to the string that i want to check. Also i am using the 2D array for keeping variable names and their address. So yes i want to keep it inside a 2D array. The question is this code is not working at all, it does not assigns i to j, so i wonder where is the problem with this idea? writing a "break" does not change if the code works or not, it just optimizes the code a little. Full Code: #include <stdio.h> #include <string.h> #include <ctype.h> double atof(char*); int main(void) { char in[100], *temp[10],var[11][10],*varptr[11][10]; int i,j, n = 0,fullval=0; double val[11]; strcpy(var[11], "ans"); for(i=0;i<11;i++) { for(j=0;j<10;j++) varptr[i][j]=&var[i][j]; } START: printf("Enter the expression: "); fflush(stdout); for(i=0;i<10;i++) temp[i]=NULL; if (fgets(in, sizeof in, stdin) != NULL) { temp[0] = strtok(in, " "); if (temp[0] != NULL) { for (n = 1; n < 10 && (temp[n] = strtok(NULL," ")) != NULL; n++) ; } if (*temp[0]=="quit") { goto FINISH;} if (isdigit(*temp[0])) { if (*temp[1]=='+') val[0] = atof(temp[0])+atof(temp[2]); else if (*temp[1]=='-') val[0] = atof(temp[0])-atof(temp[2]); else if (*temp[1]=='*') val[0] = atof(temp[0])*atof(temp[2]); else if (*temp[1]=='/') val[0] = atof(temp[0])/atof(temp[2]); printf("%s = %f\n",var[11],val[0]); goto START; } else if (temp[1]==NULL) //asking the value of a variable { for(i=0;i<10;i++) { if (strcmp(temp[0],varptr[i])==0) j=i; } printf("%s = %d\n",var[j],val[j]); goto START; } if (*temp[1]==61) { strcpy(var[fullval], temp[0]); if ((temp[3])!=NULL) { } val[fullval]=atof(temp[2]); printf("%s = %f\n",var[fullval],val[fullval]); fullval++; goto START; } if (*temp[1]!=61) { } } getch(); FINISH: return 0; }

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  • Two functions working but not when I put them together

    - by Error_404
    I'm really new to C(I have been learning Cuda and wanted to learn C so I can run everything together instead of generating data in Java/Python and copy/pasting it manually to my Cuda program to play with). I am trying to open a large file(20+gb) and parse some data but because I was having problems I decided to try to break down my problem first to verify I can open and read line by line a file and then in another file take a sample of the output of a line and try to parse it, then if all goes well I can simply bring them together. I managed(after a bit of a struggle) to get each part working but when I combine them together it doesn't work(I tried in both eclipse & QT creator. QT creator says it exited unexpectedly and eclipse just stops..). Here's the parsing part(it works exactly as I want): #include <string.h> #include <stdio.h> int main() { char line[1024] = "[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 4],"; size_t len = strlen(line); memmove(line, line+1, len-3); line[len-3] = 0; printf("%s \n",line); char str[100], *s = str, *t = NULL; strcpy(str, line); while ((t = strtok(s, " ,")) != NULL) { s = NULL; printf(":%s:\n", t); } return 0; } The data in variable line is exactly as I get if I print each line of a file. But when I copy/paste it into my main program then it doesn't work(QT shows nothing and eclipse just shows the first line). This code is just a few file IO commands that are wrapped around the commands above(everything within the while loop is the exact same as above) #include <stdio.h> #include <stdlib.h> int main() { char line[1024]; FILE *fp = fopen("/Users/me/Desktop/output.txt","r"); printf("Starting.. \n"); int count = 0; int list[30]; //items will be stored here while(fgets(line, 1024, fp) != NULL){ count++; //char line[1024] = "[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 4],"; size_t len = strlen(line); memmove(line, line+1, len-3); line[len-3] = 0; printf("%s \n",line); char str[100], *s = str, *t = NULL; strcpy(str, line); while ((t = strtok(s, " ,")) != NULL) { s = NULL; printf(":%s:\n", t); } } printf(" num of lines is %i \n", count); return 0; } eclipse output: Starting.. 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 4 I can't figure out what I'm doing wrong. I'm using a mac with gcc 4.2, if that helps. The only thing I can think of is maybe I'm doing something wrong the way I parse the list variable so its not accessible later on(I'm not sure its a wild guess). Is there anything I'm missing?

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  • file doesn't open, running outside of debugger results in seg fault (c++)

    - by misterich
    Hello (and thanks in advance) I'm in a bit of a quandry, I cant seem to figure out why I'm seg faulting. A couple of notes: It's for a course -- and sadly I am required to use use C-strings instead of std::string. Please dont fix my code (I wont learn that way and I will keep bugging you). please just point out the flaws in my logic and suggest a different function/way. platform: gcc version 4.4.1 on Suse Linux 11.2 (2.6.31 kernel) Here's the code main.cpp: // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C/C++ Std Library) #include <cstdlib> /// EXIT_SUCCESS, EXIT_FAILURE #include <iostream> /// cin, cout, ifstream #include <cassert> /// assert // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "dict.h" /// Header for the dictionary class // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR CONSTANTS #define ENTER '\n' /// Used to accept new lines, quit program. #define SPACE ' ' /// One way to end the program // /////////////////////////////////////////////////////////////////////////////////// // CUSTOM DATA TYPES /// File Namespace -- keep it local namespace { /// Possible program prompts to display for the user. enum FNS_Prompts { fileName_, /// prints out the name of the file noFile_, /// no file was passed to the program tooMany_, /// more than one file was passed to the program noMemory_, /// Not enough memory to use the program usage_, /// how to use the program word_, /// ask the user to define a word. notFound_, /// the word is not in the dictionary done_, /// the program is closing normally }; } // /////////////////////////////////////////////////////////////////////////////////// // Namespace using namespace std; /// Nothing special in the way of namespaces // /////////////////////////////////////////////////////////////////////////////////// // FUNCTIONS /** prompt() prompts the user to do something, uses enum Prompts for parameter. */ void prompt(FNS_Prompts msg /** determines the prompt to use*/) { switch(msg) { case fileName_ : { cout << ENTER << ENTER << "The file name is: "; break; } case noFile_ : { cout << ENTER << ENTER << "...Sorry, a dictionary file is needed. Try again." << endl; break; } case tooMany_ : { cout << ENTER << ENTER << "...Sorry, you can only specify one dictionary file. Try again." << endl; break; } case noMemory_ : { cout << ENTER << ENTER << "...Sorry, there isn't enough memory available to run this program." << endl; break; } case usage_ : { cout << "USAGE:" << endl << " lookup.exe [dictionary file name]" << endl << endl; break; } case done_ : { cout << ENTER << ENTER << "like Master P says, \"Word.\"" << ENTER << endl; break; } case word_ : { cout << ENTER << ENTER << "Enter a word in the dictionary to get it's definition." << ENTER << "Enter \"?\" to get a sorted list of all words in the dictionary." << ENTER << "... Press the Enter key to quit the program: "; break; } case notFound_ : { cout << ENTER << ENTER << "...Sorry, that word is not in the dictionary." << endl; break; } default : { cout << ENTER << ENTER << "something passed an invalid enum to prompt(). " << endl; assert(false); /// something passed in an invalid enum } } } /** useDictionary() uses the dictionary created by createDictionary * - prompts user to lookup a word * - ends when the user enters an empty word */ void useDictionary(Dictionary &d) { char *userEntry = new char; /// user's input on the command line if( !userEntry ) // check the pointer to the heap { cout << ENTER << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } do { prompt(word_); // test code cout << endl << "----------------------------------------" << endl << "Enter something: "; cin.getline(userEntry, INPUT_LINE_MAX_LEN, ENTER); cout << ENTER << userEntry << endl; }while ( userEntry[0] != NIL && userEntry[0] != SPACE ); // GARBAGE COLLECTION delete[] userEntry; } /** Program Entry * Reads in the required, single file from the command prompt. * - If there is no file, state such and error out. * - If there is more than one file, state such and error out. * - If there is a single file: * - Create the database object * - Populate the database object * - Prompt the user for entry * main() will return EXIT_SUCCESS upon termination. */ int main(int argc, /// the number of files being passed into the program char *argv[] /// pointer to the filename being passed into tthe program ) { // EXECUTE /* Testing code * / char tempFile[INPUT_LINE_MAX_LEN] = {NIL}; cout << "enter filename: "; cin.getline(tempFile, INPUT_LINE_MAX_LEN, '\n'); */ // uncomment after successful debugging if(argc <= 1) { prompt(noFile_); prompt(usage_); return EXIT_FAILURE; /// no file was passed to the program } else if(argc > 2) { prompt(tooMany_); prompt(usage_); return EXIT_FAILURE; /// more than one file was passed to the program } else { prompt(fileName_); cout << argv[1]; // print out name of dictionary file if( !argv[1] ) { prompt(noFile_); prompt(usage_); return EXIT_FAILURE; /// file does not exist } /* file.open( argv[1] ); // open file numEntries >> in.getline(file); // determine number of dictionary objects to create file.close(); // close file Dictionary[ numEntries ](argv[1]); // create the dictionary object */ // TEMPORARY FILE FOR TESTING!!!! //Dictionary scrabble(tempFile); Dictionary scrabble(argv[1]); // creaate the dicitonary object //*/ useDictionary(scrabble); // prompt the user, use the dictionary } // exit return EXIT_SUCCESS; /// terminate program. } Dict.h/.cpp #ifndef DICT_H #define DICT_H // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (Custom header files) #include "entry.h" /// class for dictionary entries // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define INPUT_LINE_MAX_LEN 256 /// Maximum length of each line in the dictionary file class Dictionary { public : // // Do NOT modify the public section of this class // typedef void (*WordDefFunc)(const char *word, const char *definition); Dictionary( const char *filename ); ~Dictionary(); const char *lookupDefinition( const char *word ); void forEach( WordDefFunc func ); private : // // You get to provide the private members // // VARIABLES int m_numEntries; /// stores the number of entries in the dictionary Entry *m_DictEntry_ptr; /// points to an array of class Entry // Private Functions }; #endif ----------------------------------- // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C/C++ Std Library) #include <iostream> /// cout, getline #include <fstream> // ifstream #include <cstring> /// strchr // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "dict.h" /// Header file required by assignment //#include "entry.h" /// Dicitonary Entry Class // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define COMMA ',' /// Delimiter for file #define ENTER '\n' /// Carriage return character #define FILE_ERR_MSG "The data file could not be opened. Program will now terminate." #pragma warning(disable : 4996) /// turn off MS compiler warning about strcpy() // /////////////////////////////////////////////////////////////////////////////////// // Namespace reference using namespace std; // /////////////////////////////////////////////////////////////////////////////////// // PRIVATE MEMBER FUNCTIONS /** * Sorts the dictionary entries. */ /* static void sortDictionary(?) { // sort through the words using qsort } */ /** NO LONGER NEEDED?? * parses out the length of the first cell in a delimited cell * / int getWordLength(char *str /// string of data to parse ) { return strcspn(str, COMMA); } */ // /////////////////////////////////////////////////////////////////////////////////// // PUBLIC MEMBER FUNCTIONS /** constructor for the class * - opens/reads in file * - creates initializes the array of member vars * - creates pointers to entry objects * - stores pointers to entry objects in member var * - ? sort now or later? */ Dictionary::Dictionary( const char *filename ) { // Create a filestream, open the file to be read in ifstream dataFile(filename, ios::in ); /* if( dataFile.fail() ) { cout << FILE_ERR_MSG << endl; exit(EXIT_FAILURE); } */ if( dataFile.is_open() ) { // read first line of data // TEST CODE in.getline(dataFile, INPUT_LINE_MAX_LEN) >> m_numEntries; // TEST CODE char temp[INPUT_LINE_MAX_LEN] = {NIL}; // TEST CODE dataFile.getline(temp,INPUT_LINE_MAX_LEN,'\n'); dataFile >> m_numEntries; /** Number of terms in the dictionary file * \todo find out how many lines in the file, subtract one, ingore first line */ //create the array of entries m_DictEntry_ptr = new Entry[m_numEntries]; // check for valid memory allocation if( !m_DictEntry_ptr ) { cout << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } // loop thru each line of the file, parsing words/def's and populating entry objects for(int EntryIdx = 0; EntryIdx < m_numEntries; ++EntryIdx) { // VARIABLES char *tempW_ptr; /// points to a temporary word char *tempD_ptr; /// points to a temporary def char *w_ptr; /// points to the word in the Entry object char *d_ptr; /// points to the definition in the Entry int tempWLen; /// length of the temp word string int tempDLen; /// length of the temp def string char tempLine[INPUT_LINE_MAX_LEN] = {NIL}; /// stores a single line from the file // EXECUTE // getline(dataFile, tempLine) // get a "word,def" line from the file dataFile.getline(tempLine, INPUT_LINE_MAX_LEN); // get a "word,def" line from the file // Parse the string tempW_ptr = tempLine; // point the temp word pointer at the first char in the line tempD_ptr = strchr(tempLine, COMMA); // point the def pointer at the comma *tempD_ptr = NIL; // replace the comma with a NIL ++tempD_ptr; // increment the temp def pointer // find the string lengths... +1 to account for terminator tempWLen = strlen(tempW_ptr) + 1; tempDLen = strlen(tempD_ptr) + 1; // Allocate heap memory for the term and defnition w_ptr = new char[ tempWLen ]; d_ptr = new char[ tempDLen ]; // check memory allocation if( !w_ptr && !d_ptr ) { cout << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } // copy the temp word, def into the newly allocated memory and terminate the strings strcpy(w_ptr,tempW_ptr); w_ptr[tempWLen] = NIL; strcpy(d_ptr,tempD_ptr); d_ptr[tempDLen] = NIL; // set the pointers for the entry objects m_DictEntry_ptr[ EntryIdx ].setWordPtr(w_ptr); m_DictEntry_ptr[ EntryIdx ].setDefPtr(d_ptr); } // close the file dataFile.close(); } else { cout << ENTER << FILE_ERR_MSG << endl; exit(EXIT_FAILURE); } } /** * cleans up dynamic memory */ Dictionary::~Dictionary() { delete[] m_DictEntry_ptr; /// thou shalt not have memory leaks. } /** * Looks up definition */ /* const char *lookupDefinition( const char *word ) { // print out the word ---- definition } */ /** * prints out the entire dictionary in sorted order */ /* void forEach( WordDefFunc func ) { // to sort before or now.... that is the question } */ Entry.h/cpp #ifndef ENTRY_H #define ENTRY_H // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C++ Std lib) #include <cstdlib> /// EXIT_SUCCESS, NULL // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define NIL '\0' /// C-String terminator #define MEM_ERR_MSG "Memory allocation has failed. Program will now terminate." // /////////////////////////////////////////////////////////////////////////////////// // CLASS DEFINITION class Entry { public: Entry(void) : m_word_ptr(NULL), m_def_ptr(NULL) { /* default constructor */ }; void setWordPtr(char *w_ptr); /// sets the pointer to the word - only if the pointer is empty void setDefPtr(char *d_ptr); /// sets the ponter to the definition - only if the pointer is empty /// returns what is pointed to by the word pointer char getWord(void) const { return *m_word_ptr; } /// returns what is pointed to by the definition pointer char getDef(void) const { return *m_def_ptr; } private: char *m_word_ptr; /** points to a dictionary word */ char *m_def_ptr; /** points to a dictionary definition */ }; #endif -------------------------------------------------- // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "entry.h" /// class header file // /////////////////////////////////////////////////////////////////////////////////// // PUBLIC FUNCTIONS /* * only change the word member var if it is in its initial state */ void Entry::setWordPtr(char *w_ptr) { if(m_word_ptr == NULL) { m_word_ptr = w_ptr; } } /* * only change the def member var if it is in its initial state */ void Entry::setDefPtr(char *d_ptr) { if(m_def_ptr == NULL) { m_word_ptr = d_ptr; } }

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  • Faulting DLL (ISAPI Filter)...

    - by Brad
    I wrote this ISAPI filter to rewrite the URL because we had some sites that moved locations... Basically the filter looks at the referrer, and if it's the local server, it looks at the requested URL and compared it to the full referrer. If the first path is identical, nothing is done, however if not, it takes the first path from the full referrer and prepends it to the URL. For example: /Content/imgs/img.jpg from a referrer of http://myserver/wr/apps/default.htm would be rewritten as /wr/Content/imgs/img.jpg. When I view the log file, everything looks good. However the DLL keeps faulting with the following information: Faulting application w3wp.exe, version 6.0.3790.3959, faulting module URLRedirector.dll, version 0.0.0.0, fault address 0x0002df25. Here's the code: #include <windows.h> #include <stdio.h> #include <stdlib.h> #include <httpfilt.h> #include <time.h> #include <string.h> #ifdef _DEBUG #define TO_FILE // uncomment out to use a log file #ifdef TO_FILE #define DEST ghFile #define DebugMsg(x) WriteToFile x; HANDLE ghFile; #define LOGFILE "W:\\Temp\\URLRedirector.log" void WriteToFile (HANDLE hFile, char *szFormat, ...) { char szBuf[1024]; DWORD dwWritten; va_list list; va_start (list, szFormat); vsprintf (szBuf, szFormat, list); hFile = CreateFile (LOGFILE, GENERIC_WRITE, 0, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL); if (hFile != INVALID_HANDLE_VALUE) { SetFilePointer (hFile, 0, NULL, FILE_END); WriteFile (hFile, szBuf, lstrlen (szBuf), &dwWritten, NULL); CloseHandle (hFile); } va_end (list); } #endif #endif BOOL WINAPI __stdcall GetFilterVersion(HTTP_FILTER_VERSION *pVer) { /* Specify the types and order of notification */ pVer->dwFlags = (SF_NOTIFY_ORDER_HIGH | SF_NOTIFY_SECURE_PORT | SF_NOTIFY_NONSECURE_PORT | SF_NOTIFY_PREPROC_HEADERS | SF_NOTIFY_END_OF_NET_SESSION); pVer->dwFilterVersion = HTTP_FILTER_REVISION; strcpy(pVer->lpszFilterDesc, "URL Redirector, Version 1.0"); return TRUE; } DWORD WINAPI __stdcall HttpFilterProc(HTTP_FILTER_CONTEXT *pfc, DWORD NotificationType, VOID *pvData) { CHAR *pPhysPath; PHTTP_FILTER_URL_MAP pURLMap; PHTTP_FILTER_PREPROC_HEADERS pHeaderInfo; CHAR szReferrer[255], szServer[255], szURL[255], szNewURL[255]; DWORD dwRSize = sizeof(szReferrer); DWORD dwSSize = sizeof(szServer); DWORD dwUSize = sizeof(szURL); int iTmp, iTmp2; CHAR *pos, tmp[255], *tmp2; switch (NotificationType) { case SF_NOTIFY_PREPROC_HEADERS : pHeaderInfo = (PHTTP_FILTER_PREPROC_HEADERS)pvData; if (pfc->GetServerVariable(pfc, "HTTP_REFERER", szReferrer, &dwRSize)) { DebugMsg(( DEST, "Referrer: %s\r\n", szReferrer )); if (pfc->GetServerVariable(pfc, "SERVER_NAME", szServer, &dwSSize)) DebugMsg(( DEST, "Server Name: %s\r\n", szServer )); if (pHeaderInfo->GetHeader(pfc, "URL", szURL, &dwUSize)) DebugMsg(( DEST, "URL: %s\r\n", szURL )); iTmp = strnstr(szReferrer, szServer, strlen(szReferrer)); if(iTmp > 0) { //Referred is our own server... strcpy(tmp, szReferrer + iTmp); DebugMsg(( DEST, "tmp: %s - %d\r\n", tmp, strlen(tmp) )); pos = strchr(tmp+1, '/'); DebugMsg(( DEST, "pos: %s - %d\r\n", pos, strlen(pos) )); iTmp2 = strlen(tmp) - strlen(pos) + 1; strncpy(tmp2, tmp, iTmp2); tmp2[iTmp2] = '\0'; DebugMsg(( DEST, "tmp2: %s\r\n", tmp2)); if(strncmp(szURL, tmp2, iTmp2) != 0) { //First paths don't match, create new URL... strncpy(szNewURL, tmp2, iTmp2-1); strcat(szNewURL, szURL); DebugMsg(( DEST, "newURL: %s\r\n", szNewURL)); pHeaderInfo->SetHeader(pfc, "URL", szNewURL); return SF_STATUS_REQ_HANDLED_NOTIFICATION; } } } break; default : break; } return SF_STATUS_REQ_NEXT_NOTIFICATION; } /* simple function to compare two strings and return the position at which the compare ended */ static int strnstr ( const char *string, const char *strCharSet, int n) { int len = (strCharSet != NULL ) ? ((int)strlen(strCharSet )) : 0 ; int ret, I, J, found; if ( 0 == n || 0 == len ) { return -1; } ret = -1; found = 0; for (I = 0 ; I <= n - len && found != 1 ; I++) { J = 0 ; for ( ; J < len ; J++ ) { if (toupper(string[I + J]) != toupper(strCharSet [J])) { break; // Exit For(J) } } if ( J == len) { ret = I + (J); found = 1; } } return ret; }

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  • Illustration of buffer overflows for students (linux, C)

    - by osgx
    Hello My friend is teacher of first-year CS students. We want to show them buffer overflow exploitation. But modern distribs are protected from simples buffer overflows: HOME=`perl -e "print 'A'x269"` one_widely_used_utility_is_here --help on debian (blame it) Caught signal 11, on modern commercial redhat *** buffer overflow detected ***: /usr/bin/one_widely_used_utility_is_here terminated ======= Backtrace: ========= /lib/libc.so.6(__chk_fail+0x41)[0xc321c1] /lib/libc.so.6(__strcpy_chk+0x43)[0xc315e3] /usr/bin/one_widely_used_utility_is_here[0x805xxxc] /usr/bin/one_widely_used_utility_is_here[0x804xxxc] /lib/libc.so.6(__libc_start_main+0xdc)[0xb61e9c] /usr/bin/one_widely_used_utility_is_here[0x804xxx1] ======= Memory map: ======== 00336000-00341000 r-xp 00000000 08:02 2751047 /lib/libgcc_s-4.1.2-20080825.so.1 00341000-00342000 rwxp 0000a000 08:02 2751047 /lib/libgcc_s-4.1.2-20080825.so.1 008f3000-008f4000 r-xp 008f3000 00:00 0 [vdso] The same detector fails for more synthetic examples from the internet. How can we demonstrate buffer overflow with modern non-GPL distribs (there is no debian in classes) How can we DISABLE canary word checking in stack ? DISABLE checking variants of strcpy/strcat ? write an example (in plain C) with working buffer overrun ?

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  • free() on stack memory

    - by vidicon
    I'm supporting some c code on Solaris, and I've seen something weird at least I think it is: char new_login[64]; ... strcpy(new_login, (char *)login); ... free(new_login); My understanding is that since the variable is a local array the memory comes from the stack and does not need to be freed, and moreover since no malloc/calloc/realloc was used the behaviour is undefined. This is a real-time system so I think it is a waste of cycles. Am I missing something obvious?

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  • gcc does not generate debugger info when using -g, -ggdb, -g3, or -ggdb3

    - by CJJ
    I'm using GCC 4.4.1 and GDB 7.0-ubuntu on Ubuntu 9.10. However, GCC won't generate debugger info when using any of the following switches: -g, -g3, -ggdb, or -ggdb3. So when I run the program with GDB, its as if there was no debugger information generated. I have created very simple test source files in a new, empty folder. Here is one example: #include <stdlib.h> #include <stdio.h> int main (int argc, char **argv) { char msg[4]; // allocate 4 bytes on the stack strcpy (msg, "hello world"); // overflow printf ("%s\n", msg); return 0; }

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  • parsing string off a configuration using strtok in C

    - by Jessica
    in the configuration file i have entries similar to this one: filepath = c:\Program Files\some value Where the path can contain spaces and there are no quotes on that string. I tried parsing this with strtok like: char *option; char *value; value = strtok(line, " ="); strcpy(option, value); value = strtok(NULL, " ="); where line is the line I am reading from the file, option will contain the left side of the equal (filepath) and value will contain the right side (c:\program files\some value). I know, it's poor coding, but I haven't found something better. sorry... In any case, for those options where there's no space in the right side it works great, but in those containing spaces it only return the string until the 1st space: c:\Program. Is there any other way to do this? Code is appreciated. Jessica

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