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  • bubble sort on array of c structures not sorting properly

    - by xmpirate
    I have the following program for books record and I want to sort the records on name of book. the code isn't showing any error but it's not sorting all the records. #include "stdio.h" #include "string.h" #define SIZE 5 struct books{ //define struct char name[100],author[100]; int year,copies; }; struct books book1[SIZE],book2[SIZE],*pointer; //define struct vars void sort(struct books *,int); //define sort func main() { int i; char c; for(i=0;i<SIZE;i++) //scanning values { gets(book1[i].name); gets(book1[i].author); scanf("%d%d",&book1[i].year,&book1[i].copies); while((c = getchar()) != '\n' && c != EOF); } pointer=book1; sort(pointer,SIZE); //sort call i=0; //printing values while(i<SIZE) { printf("##########################################################################\n"); printf("Book: %s\nAuthor: %s\nYear of Publication: %d\nNo of Copies: %d\n",book1[i].name,book1[i].author,book1[i].year,book1[i].copies); printf("##########################################################################\n"); i++; } } void sort(struct books *pointer,int n) { int i,j,sorted=0; struct books temp; for(i=0;(i<n-1)&&(sorted==0);i++) //bubble sort on the book name { sorted=1; for(j=0;j<n-i-1;j++) { if(strcmp((*pointer).name,(*(pointer+1)).name)>0) { //copy to temp val strcpy(temp.name,(*pointer).name); strcpy(temp.author,(*pointer).author); temp.year=(*pointer).year; temp.copies=(*pointer).copies; //copy next val strcpy((*pointer).name,(*(pointer+1)).name); strcpy((*pointer).author,(*(pointer+1)).author); (*pointer).year=(*(pointer+1)).year; (*pointer).copies=(*(pointer+1)).copies; //copy back temp val strcpy((*(pointer+1)).name,temp.name); strcpy((*(pointer+1)).author,temp.author); (*(pointer+1)).year=temp.year; (*(pointer+1)).copies=temp.copies; sorted=0; } *pointer++; } } } My Imput The C Programming Language X Y Z 1934 56 Inferno Dan Brown 1993 453 harry Potter and the soccers stone J K Rowling 2012 150 Ruby On Rails jim aurther nil 2004 130 Learn Python Easy Way gmaps4rails 1967 100 And the output ########################################################################## Book: Inferno Author: Dan Brown Year of Publication: 1993 No of Copies: 453 ########################################################################## ########################################################################## Book: The C Programming Language Author: X Y Z Year of Publication: 1934 No of Copies: 56 ########################################################################## ########################################################################## Book: Ruby On Rails Author: jim aurther nil Year of Publication: 2004 No of Copies: 130 ########################################################################## ########################################################################## Book: Learn Python Easy Way Author: gmaps4rails Year of Publication: 1967 No of Copies: 100 ########################################################################## ########################################################################## Book: Author: Year of Publication: 0 No of Copies: 0 ########################################################################## We can see the above sorting is wrong? What I'm I doing wrong?

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  • multiple timer to one process (without linking to rt)

    - by Richard
    Hi, is there any way to register multiple timer to a single process? I have tried following code, yet without success. (Use "gcc -lrt" to compile it...). Program output nothing, which should atleast print "test". Is it possibly due to the dependence to linking to rt? #define TT_SIGUSR1 (SIGRTMAX) #define TT_SIGUSR2 (SIGRTMAX - 1) #define TIME_INTERVAL_1 1 #define TIME_INTERVAL_2 2 #include <signal.h> #include <time.h> #include <stdio.h> #include <unistd.h> #include <linux/unistd.h> #include <sys/syscall.h> #include <sys/time.h> #include <sys/types.h> #include <sched.h> #include <signal.h> #include <setjmp.h> #include <errno.h> #include <assert.h> timer_t create_timer(int signo) { timer_t timerid; struct sigevent se; se.sigev_signo = signo; if (timer_create(CLOCK_REALTIME, &se, &timerid) == -1) { fprintf(stderr, "Failed to create timer\n"); exit(-1); } return timerid; } void set_timer(timer_t timerid, int seconds) { struct itimerspec timervals; timervals.it_value.tv_sec = seconds; timervals.it_value.tv_nsec = 0; timervals.it_interval.tv_sec = seconds; timervals.it_interval.tv_nsec = 0; if (timer_settime(timerid, 0, &timervals, NULL) == -1) { fprintf(stderr, "Failed to start timer\n"); exit(-1); } return; } void install_sighandler2(int signo, void(*handler)(int)) { struct sigaction sigact; sigemptyset(&sigact.sa_mask); sigact.sa_flags = SA_SIGINFO; //register the Signal Handler sigact.sa_sigaction = handler; // Set up sigaction to catch signal first timer if (sigaction(signo, &sigact, NULL) == -1) { printf("sigaction failed"); return -1; } } void install_sighandler(int signo, void(*handler)(int)) { sigset_t set; struct sigaction act; /* Setup the handler */ act.sa_handler = handler; act.sa_flags = SA_RESTART; sigaction(signo, &act, 0); /* Unblock the signal */ sigemptyset(&set); sigaddset(&set, signo); sigprocmask(SIG_UNBLOCK, &set, NULL); return; } void signal_handler(int signo) { printf("receiving sig %d", signo); } int main() { printf("test"); timer_t timer1 = create_timer(TT_SIGUSR1); timer_t timer2 = create_timer(TT_SIGUSR2); set_timer(timer1, TIME_INTERVAL_1); set_timer(timer2, TIME_INTERVAL_2); install_sighandler2(TT_SIGUSR1, signal_handler); install_sighandler(TT_SIGUSR2, signal_handler); while (1) ; return 0; }

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  • how to get rid off garbage in array of chars?

    - by fang_dejavu
    hi, I'm writing a C program but I keep having problems with my array of chars. I keep getting garbage when I print it using prinf. here is an example of what I get when I print it: char at t.symbol is Aôÿ¿ char at tabl[0].symbol is A char at tabl[1].symbol is a char at tabl[2].symbol is a char at tabl[3].symbol is d char at tabl[4].symbol is e char at tabl[5].symbol is f char at tabl[6].symbol is g char at tabl[7].symbol is h char at tabl[8].symbol is i char at tabl[9].symbol is x char at t[0].symbol is a0AÃ char at t[1].symbol is b)@Ã4 char at t[2].symbol is ckU* char at t[3].symbol is Aôÿ¿ char at t[4].symbol is gØ could someone tell me how to get rid off the garbage in the array of chars? here is my code #define MAX 100 #ifndef SYMBSIZE #define SYMBSIZE 1 #endif typedef struct tableme { char symbol[SYMBSIZE]; int value; int casenmbr; int otherinfo; }tabletype; int main(int argc, char **argv) { tabletype t[MAX]; t[3].symbol[0] = 'A'; t[0].value=1; t[0].casenmbr = 7; t[0].otherinfo = 682; tabletype tabl[MAX]; tabl[0].value = 1; tabl[0].symbol[0] = 'A'; tabl[1].value = 11; tabl[1].symbol[0]= 'a'; tabl[2].value = 12; tabl[2].symbol[0] = 'a'; tabl[3].value = 13; tabl[3].symbol[0] = 'd'; tabl[4].value = 14; tabl[4].symbol[0] = 'e'; tabl[5].value = 15; tabl[5].symbol[0] = 'f'; tabl[6].value = 16; tabl[6].symbol[0] = 'g'; tabl[7].value = 17; tabl[7].symbol[0] = 'h'; tabl[8].symbol[0] = 'i'; tabl[9].symbol[0] = 'x'; t[1].symbol[0] = 'b'; t[0].symbol[0]= 'a'; t[2].symbol[0]= 'c'; t[4].symbol[0]= 'g'; printf("char at t.symbol is %s \n", t[3].symbol); for( x=0;x<10;x++) { printf("char at tabl[%d].symbol is %s \n",x, tabl[x].symbol); } int j; for(j = 0; j<5;j++) { printf("char at t[%d].symbol is %s \n",j, t[j].symbol); } return 0; }

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  • OpenGL/GLSL: Render to cube map?

    - by BobDole
    I'm trying to figure out how to render my scene to a cube map. I've been stuck on this for a bit and figured I would ask you guys for some help. I'm new to OpenGL and this is the first time I'm using a FBO. I currently have a working example of using a cubemap bmp file, and the samplerCube sample type in the fragment shader is attached to GL_TEXTURE1. I'm not changing the shader code at all. I'm just changing the fact that I wont be calling the function that was loading the cubemap bmp file and trying to use the below code to render to a cubemap. You can see below that I'm also attaching the texture again to GL_TEXTURE1. This is so when I set the uniform: glUniform1i(getUniLoc(myProg, "Cubemap"), 1); it can access it in my fragment shader via uniform samplerCube Cubemap. I'm calling the below function like so: cubeMapTexture = renderToCubeMap(150, GL_RGBA8, GL_RGBA, GL_UNSIGNED_BYTE); Now, I realize in the draw loop below that I'm not changing the view direction to look down the +x, -x, +y, -y, +z, -z axis. I really was just wanting to see something working first before implemented that. I figured I should at least see something on my object the way the code is now. I'm not seeing anything, just straight black. I've made my background white still the object is black. I've removed lighting, and coloring to just sample the cubemap texture and still black. I'm thinking the problem might be the format types when setting my texture which is GL_RGB8, GL_RGBA but I've also tried: GL_RGBA, GL_RGBA GL_RGB, GL_RGB I thought this would be standard since we are rendering to a texture attached to a framebuffer, but I've seen different examples that use different enum values. I've also tried binding the cube map texture in every draw call that I'm wanting to use the cube map: glBindTexture(GL_TEXTURE_CUBE_MAP, cubeMapTexture); Also, I'm not creating a depth buffer for the FBO which I saw in most examples, because I'm only wanting the color buffer for my cube map. I actually added one to see if that was the problem and still got the same results. I could of fudged that up when I tried. Any help that can point me in the right direction would be appreciated. GLuint renderToCubeMap(int size, GLenum InternalFormat, GLenum Format, GLenum Type) { // color cube map GLuint textureObject; int face; GLenum status; //glEnable(GL_TEXTURE_2D); glActiveTexture(GL_TEXTURE1); glGenTextures(1, &textureObject); glBindTexture(GL_TEXTURE_CUBE_MAP, textureObject); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE); for (face = 0; face < 6; face++) { glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, 0, InternalFormat, size, size, 0, Format, Type, NULL); } // framebuffer object glGenFramebuffers(1, &fbo); glBindFramebuffer(GL_FRAMEBUFFER, fbo); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X, textureObject, 0); status = glCheckFramebufferStatus(GL_FRAMEBUFFER); printf("%d\"\n", status); printf("%d\n", GL_FRAMEBUFFER_COMPLETE); glViewport(0,0,size, size); for (face = 1; face < 6; face++) { drawSpheres(); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, textureObject, 0); } //Bind 0, which means render to back buffer, as a result, fb is unbound glBindFramebuffer(GL_FRAMEBUFFER, 0); return textureObject; }

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  • Child transforms problem when loading 3DS models using assimp

    - by MhdSyrwan
    I'm trying to load a textured 3d model into my scene using assimp model loader. The problem is that child meshes are not situated correctly (they don't have the correct transformations). In brief: all the mTansform matrices are identity matrices, why would that be? I'm using this code to render the model: void recursive_render (const struct aiScene *sc, const struct aiNode* nd, float scale) { unsigned int i; unsigned int n=0, t; aiMatrix4x4 m = nd->mTransformation; m.Scaling(aiVector3D(scale, scale, scale), m); // update transform m.Transpose(); glPushMatrix(); glMultMatrixf((float*)&m); // draw all meshes assigned to this node for (; n < nd->mNumMeshes; ++n) { const struct aiMesh* mesh = scene->mMeshes[nd->mMeshes[n]]; apply_material(sc->mMaterials[mesh->mMaterialIndex]); if (mesh->HasBones()){ printf("model has bones"); abort(); } if(mesh->mNormals == NULL) { glDisable(GL_LIGHTING); } else { glEnable(GL_LIGHTING); } if(mesh->mColors[0] != NULL) { glEnable(GL_COLOR_MATERIAL); } else { glDisable(GL_COLOR_MATERIAL); } for (t = 0; t < mesh->mNumFaces; ++t) { const struct aiFace* face = &mesh->mFaces[t]; GLenum face_mode; switch(face->mNumIndices) { case 1: face_mode = GL_POINTS; break; case 2: face_mode = GL_LINES; break; case 3: face_mode = GL_TRIANGLES; break; default: face_mode = GL_POLYGON; break; } glBegin(face_mode); for(i = 0; i < face->mNumIndices; i++)// go through all vertices in face { int vertexIndex = face->mIndices[i];// get group index for current index if(mesh->mColors[0] != NULL) Color4f(&mesh->mColors[0][vertexIndex]); if(mesh->mNormals != NULL) if(mesh->HasTextureCoords(0))//HasTextureCoords(texture_coordinates_set) { glTexCoord2f(mesh->mTextureCoords[0][vertexIndex].x, 1 - mesh->mTextureCoords[0][vertexIndex].y); //mTextureCoords[channel][vertex] } glNormal3fv(&mesh->mNormals[vertexIndex].x); glVertex3fv(&mesh->mVertices[vertexIndex].x); } glEnd(); } } // draw all children for (n = 0; n < nd->mNumChildren; ++n) { recursive_render(sc, nd->mChildren[n], scale); } glPopMatrix(); } What's the problem in my code ? I've added some code to abort the program if there's any bone in the meshes, but the program doesn't abort, this means : no bones, is that normal? if (mesh->HasBones()){ printf("model has bones"); abort(); } Note: I am using openGL & SFML & assimp

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  • CreateProcess doesn't pass command line arguments

    - by mnh
    Hello I have the following code but it isn't working as expected, can't figure out what the problem is. Basically, I'm executing a process (a .NET process) and passing it command line arguments, it is executed successfully by CreateProcess() but CreateProcess() isn't passing the command line arguments What am I doing wrong here?? int main(int argc, char* argv[]) { PROCESS_INFORMATION ProcessInfo; //This is what we get as an [out] parameter STARTUPINFO StartupInfo; //This is an [in] parameter ZeroMemory(&StartupInfo, sizeof(StartupInfo)); StartupInfo.cb = sizeof StartupInfo ; //Only compulsory field LPTSTR cmdArgs = "[email protected]"; if(CreateProcess("D:\\email\\smtp.exe", cmdArgs, NULL,NULL,FALSE,0,NULL, NULL,&StartupInfo,&ProcessInfo)) { WaitForSingleObject(ProcessInfo.hProcess,INFINITE); CloseHandle(ProcessInfo.hThread); CloseHandle(ProcessInfo.hProcess); printf("Yohoo!"); } else { printf("The process could not be started..."); } return 0; } EDIT: Hey one more thing, if I pass my cmdArgs like this: // a space as the first character LPTSTR cmdArgs = " [email protected]"; Then I get the error, then CreateProcess returns TRUE but my target process isn't executed. Object reference not set to an instance of an object

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  • How does Visual Studio decide the order in which stack variables should be allocated?

    - by Jason
    I'm trying to turn some of the programs in gera's Insecure Programming by example into client/server applications that could be used in capture the flag scenarios to teach exploit development. The problem I'm having is that I'm not sure how Visual Studio (I'm using 2005 Professional Edition) decides where to allocate variables on the stack. When I compile and run example 1: int main() { int cookie; char buf[80]; printf("buf: %08x cookie: %08x\n", &buf, &cookie); gets(buf); if (cookie == 0x41424344) printf("you win!\n"); } I get the following result: buf: 0012ff14 cookie: 0012ff64 buf starts at an address eighty bytes lower than cookie, and any four bytes that are copied in buf after the first eighty will appear in cookie. The problem I'm having is when I place this code in some other function. When I compile and run the following code, I get a different result: buf appears at an address greater than cookie's. void ClientSocketHandler(SOCKET cs){ int cookie; char buf[80]; char stringToSend[160]; int numBytesRecved; int totalNumBytes; sprintf(stringToSend,"buf: %08x cookie: %08x\n",&buf,&cookie); send(cs,stringToSend,strlen(stringToSend),NULL); The result is: buf: 0012fd00 cookie: 0012fcfc Now there is no way to set cookie to arbitrary data via overwriting buf. Is there any way to tell Visual Studio to allocate cookie before buf? Is there any way to tell beforehand how the variables will be allocated? Thanks, Jason

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  • DFS function, can you guys tell me what is the wrong with this code?

    - by danielDhobbs
    can you guys tell me what is the wrong with this code? it is not working with 1 2 1 3 1 4 2 5 2 6 2 7 2 8 3 8 3 9 4 10 1 - 4 - 10 and stop DFS function void Is_Connected(graphType* g, int v){ //function to define the graph is connected or not int i=0; g_node* w; top = NULL; g -> visited[v] = TRUE; push(v); printf("%d", v); while (top != NULL) { w = g -> adjList[v]; while (w) { if (!g -> visited[w -> vertex]) { push(w -> vertex); g -> visited[w -> vertex] = TRUE; printf("->%d", w->vertex); v = w -> vertex; w = g -> adjList[v]; } else { w = w -> link; } } i++; v = pop(); } if (i == (g -> x)-1){ //number of vertices = number of vertetices pass through puts("\nIs_Connected() result : yes"); } else{ puts("\nIs_Connected() result : no"); } }

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  • I have having following warning in gcc compilation in 32 bit architecture but not having any such wa

    - by thetna
    symbol.c: In function 'symbol_FPrint': symbol.c:1209: warning: format '%ld' expects type 'long int', but argument 3 has type 'SYMBOL' symbol.c: In function 'symbol_FPrintOtter': symbol.c:1236: warning: format '%ld' expects type 'long int', but argument 3 has type 'SYMBOL' symbol.c:1239: warning: format '%ld' expects type 'long int', but argument 3 has type 'SYMBOL' symbol.c:1243: warning: format '%ld' expects type 'long int', but argument 3 has type 'SYMBOL' symbol.c:1266: warning: format '%ld' expects type 'long int', but argument 3 has type 'SYMBOL' In symbol.c 1198 #ifdef CHECK 1199 else { 1200 misc_StartErrorReport(); 1201 misc_ErrorReport("\n In symbol_FPrint: Cannot print symbol.\n"); 1202 misc_FinishErrorReport(); 1203 } 1204 #endif 1205 } 1206 else if (symbol_SignatureExists()) 1207 fputs(symbol_Name(Symbol), File); 1208 else 1209 fprintf(File, "%ld", Symbol); 1210 } And SYMBOL is defined as: typedef size_t SYMBOL When i replaced '%ld' with '%zu' , i got the following warning: symbol.c: In function 'symbol_FPrint': symbol.c:1209: warning: ISO C90 does not support the 'z' printf length modifier Note: From here it has been edited on 26th of march 2010 and and following problem has beeen added because of its similarity to the above mentioned problem. I have following statement: printf("\n\t %4d:%4d:%4d:%4d:%4d:%s:%d", Index, S->info, S->weight, Precedence[Index],S->props,S->name, S->length); The warning I get while compiling in 64 bit architecture is : format ‘%4d’ expects type ‘int’, but argument 5 has type ‘size_t’ here are the definitions of parameter: NAT props; typedef unsigned int NAT; How can i get rid of this so that i can compile without warning in 32 and 64 bit architecture? What can be its solution?

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  • Passing char * into fopen with C.

    - by Rhys
    Hey there, I'm writing a program that passes data from a file into an array, but I'm having trouble with fopen (). It seems to work fine when I hardcode the file path into the parameters (eg fopen ("data/1.dat", "r");) but when I pass it as a pointer, it returns NULL. Note that line 142 will print "data/1.dat" if entered from command line so parse_args () appears to be working. 132 int 133 main(int argc, char **argv) 134 { 135 FILE *in_file; 136 int *nextItem = (int *) malloc (sizeof (int)); 137 set_t *dictionary; 138 139 /* Parse Arguments */ 140 clo_t *iopts = parse_args(argc, argv); 141 142 printf ("INPUT FILE: %s.\n", iopts->input_file); /* This prints correct path */ 143 /* Initialise dictionary */ 144 dictionary = set_create (SET_INITAL_SIZE); 145 146 /* Use fscanf to read all data values into new set_t */ 147 if ((in_file = fopen (iopts->input_file, "r")) == NULL) 148 { 149 printf ("File not found...\n"); 150 return 0; 151 } Thanks! Rhys

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  • How do I test OpenCL on GPU when logged in remotely on Mac?

    - by Christopher Bruns
    My OpenCL program can find the GPU device when I am logged in at the console, but not when I am logged in remotely with ssh. Further, if I run the program as root in the ssh session, the program can find the GPU. The computer is a Snow Leopard Mac with a GeForce 9400 GPU. If I run the program (see below) from the console or as root, the output is as follows (notice the "GeForce 9400" line): 2 devices found Device #0 name = GeForce 9400 Device #1 name = Intel(R) Core(TM)2 Duo CPU P8700 @ 2.53GHz but if it is just me, over ssh, there is no GeForce 9400 entry: 1 devices found Device #0 name = Intel(R) Core(TM)2 Duo CPU P8700 @ 2.53GHz I would like to test my code on the GPU without having to be root. Is that possible? Simplified GPU finding program below: #include <stdio.h> #include <OpenCL/opencl.h> int main(int argc, char** argv) { char dname[500]; size_t namesize; cl_device_id devices[10]; cl_uint num_devices; int d; clGetDeviceIDs(0, CL_DEVICE_TYPE_ALL, 10, devices, &num_devices); printf("%d devices found\n", num_devices); for (d = 0; d < num_devices; ++d) { clGetDeviceInfo(devices[d], CL_DEVICE_NAME, 500, dname, &namesize); printf("Device #%d name = %s\n", d, dname); } return 0; } EDIT: I found essentially the same question being asked on nvidia's forums. Unfortunately, the only answer was of the form "this is the wrong forum".

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  • How do you capture a group with regex?

    - by Sylvain
    Hi, I'm trying to extract a string from another using regex. I'm using the POSIX regex functions (regcomp, regexec ...), and I fail at capturing a group ... For instance, let the pattern be something as simple as "MAIL FROM:<(.*)>" (with REG_EXTENDED cflags) I want to capture everything between '<' and '' My problem is that regmatch_t gives me the boundaries of the whole pattern (MAIL FROM:<...) instead of just what's between the parenthesis ... What am I missing ? Thanks in advance, edit: some code #define SENDER_REGEX "MAIL FROM:<(.*)>" int main(int ac, char **av) { regex_t regex; int status; regmatch_t pmatch[1]; if (regcomp(&regex, SENDER_REGEX, REG_ICASE|REG_EXTENDED) != 0) printf("regcomp error\n"); status = regexec(&regex, av[1], 1, pmatch, 0); regfree(&regex); if (!status) printf( "matched from %d (%c) to %d (%c)\n" , pmatch[0].rm_so , av[1][pmatch[0].rm_so] , pmatch[0].rm_eo , av[1][pmatch[0].rm_eo] ); return (0); } outputs: $./a.out "012345MAIL FROM:<abcd>$" matched from 6 (M) to 22 ($) solution: as RarrRarrRarr said, the indices are indeed in pmatch[1].rm_so and pmatch[1].rm_eo hence regmatch_t pmatch[1]; becomes regmatch_t pmatch[2]; and regexec(&regex, av[1], 1, pmatch, 0); becomes regexec(&regex, av[1], 2, pmatch, 0); Thanks :)

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  • Some general C questions.

    - by b-gen-jack-o-neill
    Hello. I am trying to fully understand the process pro writing code in some language to execution by OS. In my case, the language would be C and the OS would be Windows. So far, I read many different articles, but I am not sure, whether I understand the process right, and I would like to ask you if you know some good articles on some subjects I couldn´t find. So, what I think I know about C (and basically other languages): C compiler itself handles only data types, basic math operations, pointers operations, and work with functions. By work with functions I mean how to pass argument to it, and how to get output from function. During compilation, function call is replaced by passing arguments to stack, and than if function is not inline, its call is replaced by some symbol for linker. Linker than find the function definition, and replace the symbol to jump adress to that function (and of course than jump back to program). If the above is generally true and I get it right, where to final .exe file actually linker saves the functions? After the main() function? And what creates the .exe header? Compiler or Linker? Now, additional capabilities of C, today known as C standart library is set of functions and the declarations of them, that other programmers wrote to extend and simplify use of C language. But these functions like printf() were (or could be?) written in different language, or assembler. And there comes my next question, can be, for example printf() function be written in pure C without use of assembler? I know this is quite big question, but I just mostly want to know, wheather I am right or not. And trust me, I read a lots of articles on the web, and I would not ask you, If I could find these infromation together on one place, in one article. Insted I must piece by piece gather informations, so I am not sure if I am right. Thanks.

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  • Execution time in nano seconds and related issues

    - by anup
    Hi All, I am using the following code to compute execution time in milli-secs. struct timespec tp; if (clock_gettime (CLOCK_REALTIME, &tp) == 0) return ((tp.tv_sec * 1000000000) + tp.tv_nsec); else return ; Can you please tell me whether this is correct? Let's name this function comptime_nano(). Now, I write the following code in main() to check execution times of following operations. unsigned long int a, b, s1, s3; a = (unsigned long int)(1) << 63; b = (unsigned long int)(1) << 63; btime = comptime_nano(); s1 = b >> 30; atime = comptime_nano(); printf ("Time =%ld for %lu\n", (atime - btime), s1); btime = comptime_nano(); s3 = a >> 1; atime = comptime_nano(); printf ("Time =%ld for %lu\n", (atime - btime), s3); To my surprise, the first operation takes about roughly 4 times more time than the second. Again, if I change the relative ordering of these operations, the respective timings change drastically. Please comment...

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  • Making a switch statement in C with an array?

    - by Eric
    I am trying to make a switch statement that takes in a word into an array and then throws each letter through a switch statement and allocates a point to each letter depending on which letter it is and giving a final point value for the word, and I can't seem to get the array part right. Any help would be appreciated! int main(){ int letter_points = 0; char word[7]; int word_length = 7; int i; printf("Enter a Word\n"); scanf("%s", word); for(i = 0; i < word_length; i++){ switch(word){ //1 point case 'A': case 'E': case 'I': case 'L': case 'N': case 'O': case 'R': case 'S': case 'T': case 'U': letter_points++; break; //2 points case 'D': case 'G': letter_points += 2; break; //3 points case 'B': case 'C': case 'M': case 'P': letter_points += 3; break; //4 points case 'F': case 'H': case 'V': case 'W': case 'Y': letter_points += 4; break; //5 points case 'K': letter_points += 5; break; //8 points case 'J': case 'X': letter_points += 8; break; //10 points case 'Q': case 'Z': letter_points += 10; break; } } printf("%d\n", letter_points); return; }

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  • Debugging Maya plug-ins: can't get output or debugger to engage

    - by brainjam
    I'm not a total beginner at Maya, but this is my first time trying to write a plug-in for it. I've downloaded the 30-day eval version of Maya2011 (32bit version on 64bit Windows 7), and have tried building a couple of plug-ins with VC 2008 Express. The first one is helloWorldCmd from the sample directory ..\devkit\plug-ins, and it basically doesn't work until you convert the line cout<<"Hello World"<<endl; to cerr<<"Hello World"<<endl;, but I can live with that. The second one is the SelectRingContext2 example from David Gould's book. The plug-in works as advertised, but I cannot get any debugging output from it. I've tried putting cout, cerr,printf, and MGlobal::displayInfo into the doIt() method, and can't get a peep. I also haven't figured out how to run the plug-in in a debugger. I'm afraid I'm missing something easy but slightly obscure, like a flag somewhere. Anybody out there have any hints? Edit: Turns out the action is happening in the redoIt() method. So I can get MGlobal::displayInfo and cerr producing output. Still don't know why cout and printf don't work, and I'm not sure how to run in the debugger. When I run maya -d (which some of the online advice says I should do) it just shows the output window but never loads the rest.

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  • C-macro: set a register field defined by a bit-mask to a given value

    - by geschema
    I've got 32-bit registers with field defined as bit-masks, e.g. #define BM_TEST_FIELD 0x000F0000 I need a macro that allows me to set a field (defined by its bit-mask) of a register (defined by its address) to a given value. Here's what I came up with: #include <stdio.h> #include <assert.h> typedef unsigned int u32; /* * Set a given field defined by a bit-mask MASK of a 32-bit register at address * ADDR to a value VALUE. */ #define SET_REGISTER_FIELD(ADDR, MASK, VALUE) \ { \ u32 mask=(MASK); u32 value=(VALUE); \ u32 mem_reg = *(volatile u32*)(ADDR); /* Get current register value */ \ assert((MASK) != 0); /* Null masks are not supported */ \ while(0 == (mask & 0x01)) /* Shift the value to the left until */ \ { /* it aligns with the bit field */ \ mask = mask >> 1; value = value << 1; \ } \ mem_reg &= ~(MASK); /* Clear previous register field value */ \ mem_reg |= value; /* Update register field with new value */ \ *(volatile u32*)(ADDR) = mem_reg; /* Update actual register */ \ } /* Test case */ #define BM_TEST_FIELD 0x000F0000 int main() { u32 reg = 0x12345678; printf("Register before: 0x%.8X\n", reg);/* should be 0x12345678 */ SET_REGISTER_FIELD(&reg, BM_TEST_FIELD, 0xA); printf("Register after: 0x%.8X\n", reg); /* should be 0x123A5678 */ return 0; } Is there a simpler way to do it?

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  • c - strncpy issue

    - by Joe
    Hi there, I am getting segmentation fault when using strncpy and (pointer-to-struct)-(member) notation: I have simplified my code. I initialise a struct and set all of it's tokens to an empty string. Then a declare a pointer to a struct and assign the address of the struct to it. I pass the pointer to a function. I can print out the contents of the struct at the beginning of the function, but if I try to use the tp - mnemonic in a strncpy function, I get seg fault. Can anyone tell me what I am doing wrong? typedef struct tok { char* label; char* mnem; char* operand; }Tokens; Tokens* tokenise(Tokens* tp, char* line) { // This prints fine printf("Print this - %s\n", tp -> mnem); // This function gives me segmentation fault strncpy(tp -> mnem, line, 4); return tp; } int main() { char* line = "This is a line"; Tokens tokens; tokens.label = ""; tokens.mnem = "load"; tokens.operand = ""; Tokens* tp = &tokens; tp = tokenise(tp, line); return 0; } I have used printf statements to confirm that the code definitely stops executing at the strncpy function. Can anyone tell me where I am going wrong? Many thanks Joe

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  • Visual Studio expression containing a term named "by" cannot be evaluated in the watch window

    - by Andrei Pana
    Consider my C++ code below: int _tmain(int argc, _TCHAR* argv[]) { int by = 10; printf("%d\n", by); int bx = 20; printf("%d\n", (by + bx)); return 0; } which works fine. The funny thing is with the "by" variable. If I try to add a watch for a simple expression that contains by, the result will be CXX0030: Error: expression cannot be evaluated. For example, on a breakpoint on return 0, if I add the following watches I get the results mentioned: by : 10 bx : 20 by + 5 : CXX0030: Error: expression cannot be evaluated bx + 5 : 25 by + bx : CXX0030: Error: expression cannot be evaluated (by) + bx : 30 by + (bx) : CXX0030: Error: expression cannot be evaluated bx + (by) : CXX0014: Error: missing operrand This happens on VS2010, VS2008 on multiple computers. So, more out of curiosity, what is happening with "by"? Is it some kind of strange operator? Why doesn't bx get the same treatment? (I've tried google on this but it is quite difficult to get some relevant hits with terms like "by")

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  • Direct invocation vs indirect invocation in C

    - by Mohit Deshpande
    I am new to C and I was reading about how pointers "point" to the address of another variable. So I have tried indirect invocation and direct invocation and received the same results (as any C/C++ developer could have predicted). This is what I did: int cost; int *cost_ptr; int main() { cost_ptr = &cost; //assign pointer to cost cost = 100; //intialize cost with a value printf("\nDirect Access: %d", cost); cost = 0; //reset the value *cost_ptr = 100; printf("\nIndirect Access: %d", *cost_ptr); //some code here return 0; //1 } So I am wondering if indirect invocation with pointers has any advantages over direct invocation or vice-versa. Some advantages/disadvantages could include speed, amount of memory consumed performing the operation (most likely the same but I just wanted to put that out there), safeness (like dangling pointers) , good programming practice, etc. 1Funny thing, I am using the GNU C Compiler (gcc) and it still compiles without the return statement and everything is as expected. Maybe because the C++ compiler will automatically insert the return statement if you forget.

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  • How do I get uri of HTTP packet with winpcap?

    - by Gtker
    Based on this article I can get all incoming packets. /* Callback function invoked by libpcap for every incoming packet */ void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data) { struct tm *ltime; char timestr[16]; ip_header *ih; udp_header *uh; u_int ip_len; u_short sport,dport; time_t local_tv_sec; /* convert the timestamp to readable format */ local_tv_sec = header->ts.tv_sec; ltime=localtime(&local_tv_sec); strftime( timestr, sizeof timestr, "%H:%M:%S", ltime); /* print timestamp and length of the packet */ printf("%s.%.6d len:%d ", timestr, header->ts.tv_usec, header->len); /* retireve the position of the ip header */ ih = (ip_header *) (pkt_data + 14); //length of ethernet header /* retireve the position of the udp header */ ip_len = (ih->ver_ihl & 0xf) * 4; uh = (udp_header *) ((u_char*)ih + ip_len); /* convert from network byte order to host byte order */ sport = ntohs( uh->sport ); dport = ntohs( uh->dport ); /* print ip addresses and udp ports */ printf("%d.%d.%d.%d.%d -> %d.%d.%d.%d.%d\n", ih->saddr.byte1, ih->saddr.byte2, ih->saddr.byte3, ih->saddr.byte4, sport, ih->daddr.byte1, ih->daddr.byte2, ih->daddr.byte3, ih->daddr.byte4, dport); } But how do I extract URI information in packet_handler?

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  • Using fgets to read strings from file in C

    - by Ivan
    I am trying to read strings from a file that has each string on a new line but I think it reads a newline character once instead of a string and I don't know why. If I'm going about reading strings the wrong way please correct me. i=0; F1 = fopen("alg.txt", "r"); F2 = fopen("tul.txt", "w"); if(!feof(F1)) { do{ //start scanning file fgets(inimene[i].Enimi, 20, F1); fgets(inimene[i].Pnimi, 20, F1); fgets(inimene[i].Kood, 12, F1); printf("i=%d\nEnimi=%s\nPnimi=%s\nKaad=%s",i,inimene[i].Enimi,inimene[i].Pnimi,inimene[i].Kood); i++;} while(!feof(F1));}; /*finish getting structs*/ The printf is there to let me see what was read into what and here is the result i=0 Enimi=peter Pnimi=pupkin Kood=223456iatb i=1 Enimi= Pnimi=masha Kaad=gubkina i=2 Enimi=234567iasb Pnimi=sasha Kood=dudkina As you can see after the first struct is read there is a blank(a newline?) onct and then everything is shifted. I suppose I could read a dummy string to absorb that extra blank and then nothing would be shifted, but that doesn't help me understand the problem and avoid in the future.

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  • Double Free inside of a destructor upon adding to a vector

    - by Shawn B
    Hey, I am working on a drum machine, and am having problems with vectors. Each Sequence has a list of samples, and the samples are ordered in a vector. However, when a sample is push_back on the vector, the sample's destructor is called, and results in a double free error. Here is the Sample creation code: class XSample { public: Uint8 Repeat; Uint8 PlayCount; Uint16 Beats; Uint16 *Beat; Uint16 BeatsPerMinute; XSample(Uint16 NewBeats,Uint16 NewBPM,Uint8 NewRepeat); ~XSample(); void GenerateSample(); void PlaySample(); }; XSample::XSample(Uint16 NewBeats,Uint16 NewBPM,Uint8 NewRepeat) { Beats = NewBeats; BeatsPerMinute = NewBPM; Repeat = NewRepeat-1; PlayCount = 0; printf("XSample Construction\n"); Beat = new Uint16[Beats]; } XSample::~XSample() { printf("XSample Destruction\n"); delete [] Beat; } And the 'Dynamo' code that creates each sample in the vector: class XDynamo { public: std::vector<XSample> Samples; void CreateSample(Uint16 NewBeats,Uint16 NewBPM,Uint8 NewRepeat); }; void XDynamo::CreateSample(Uint16 NewBeats,Uint16 NewBPM,Uint8 NewRepeat) { Samples.push_back(XSample(NewBeats,NewBPM,NewRepeat)); } Here is main(): int main() { XDynamo Dynamo; Dynamo.CreateSample(4,120,2); Dynamo.CreateSample(8,240,1); return 0; } And this is what happens when the program is run: Starting program: /home/shawn/dynamo2/dynamo [Thread debugging using libthread_db enabled] XSample Construction XSample Destruction XSample Construction XSample Destruction *** glibc detected *** /home/shawn/dynamo2/dynamo: double free or corruption (fasttop): 0x0804d008 *** However, when the delete [] is removed from the destructor, the program runs perfectly. What is causing this? Any help is greatly appreciated.

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  • Reading Serial Data From C (OSX /dev/tty)

    - by Jud Stephenson
    I am trying to read data from a bluetooth barcode scanner (KDC300) using C. Here is the code I have so far, and the program successfully establishes a bluetooth connection to the scanner, but when a barcode is scanned, no input is displayed on the screen (Eventually more will be done with the data, but we have to get it working first, right). Here is the program: #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <fcntl.h> #include <errno.h> #include <termios.h> #include <sys/ioctl.h> int main (int argc, const char * argv[]) { // define vars int STOP = 0; //char buf[255]; if(argv[1]) { int fd = open("/dev/tty.KDC1", O_RDONLY); if(fd == -1) { printf("%s", strcat("Unable to open /dev/tty.", argv[1])); } int res; while(STOP == 0) { while((res = read(fd,buf,255)) == 0); { if(res > 0) { buf[res]=0; printf("%s:%d\n", buf, res); if(buf[sizeof(buf)]=='\n') break; } } } } return 0; } If anyone has any ideas, I am at a loss on this so far. If it is any help, I can run screen /dev/tty.KDC1 and any barcodes scanned on the scanner appear in the terminal, I just can't do anything with the data. Jud

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  • Writing re-entrant lexer with Flex

    - by Viet
    I'm newbie to flex. I'm trying to write a simple re-entrant lexer/scanner with flex. The lexer definition goes below. I get stuck with compilation errors as shown below (yyg issue): reentrant.l: /* Definitions */ digit [0-9] letter [a-zA-Z] alphanum [a-zA-Z0-9] identifier [a-zA-Z_][a-zA-Z0-9_]+ integer [0-9]+ natural [0-9]*[1-9][0-9]* decimal ([0-9]+\.|\.[0-9]+|[0-9]+\.[0-9]+) %{ #include <stdio.h> #define ECHO fwrite(yytext, yyleng, 1, yyout) int totalNums = 0; %} %option reentrant %option prefix="simpleit_" %% ^(.*)\r?\n printf("%d\t%s", yylineno++, yytext); %% /* Routines */ int yywrap(yyscan_t yyscanner) { return 1; } int main(int argc, char* argv[]) { yyscan_t yyscanner; if(argc < 2) { printf("Usage: %s fileName\n", argv[0]); return -1; } yyin = fopen(argv[1], "rb"); yylex(yyscanner); return 0; } Compilation errors: vietlq@mylappie:~/Desktop/parsers/reentrant$ gcc lex.simpleit_.c reentrant.l: In function ‘main’: reentrant.l:44: error: ‘yyg’ undeclared (first use in this function) reentrant.l:44: error: (Each undeclared identifier is reported only once reentrant.l:44: error: for each function it appears in.)

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