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  • boost.asio error on read from socket.

    - by niXman
    The following code of the client: typedef boost::array<char, 10> header_packet; header_packet header; boost::system::error_code error; ... /** send header */ boost::asio::write( _socket, boost::asio::buffer(header, header.size()), boost::asio::transfer_all(), error ); /** send body */ boost::asio::write( _socket, boost::asio::buffer(buffer, buffer.length()), boost::asio::transfer_all(), error ); of the server: struct header { boost::uint32_t header_length; boost::uint32_t id; boost::uint32_t body_length; }; static header unpack_header(const header_packet& data) { header hdr; sscanf(data.data(), "%02d%04d%04d", &hdr.header_length, &hdr.id, &hdr.body_length); return hdr; } void connection::start() { boost::asio::async_read( _socket, boost::asio::buffer(_header, _header.size()), boost::bind( &connection::read_header_handler, shared_from_this(), boost::asio::placeholders::error ) ); } /***************************************************************************/ void connection::read_header_handler(const boost::system::error_code& e) { if ( !e ) { std::cout << "readed header: " << _header.c_array() << std::endl; std::cout << constants::unpack_header(_header); boost::asio::async_read( _socket, boost::asio::buffer(_body, constants::unpack_header(_header).body_length), boost::bind( &connection::read_body_handler, shared_from_this(), boost::asio::placeholders::error ) ); } else { /** report error */ std::cout << "read header finished with error: " << e.message() << std::endl; } } /***************************************************************************/ void connection::read_body_handler(const boost::system::error_code& e) { if ( !e ) { std::cout << "readed body: " << _body.c_array() << std::endl; start(); } else { /** report error */ std::cout << "read body finished with error: " << e.message() << std::endl; } } On the server side the method read_header_handler() is called, but the method read_body_handler() is never called. Though the client has written down the data in a socket. The header is readed and decoded successfully. What's the error?

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  • Problem intialising 2D array

    - by TeeJay
    Ok, so I have a 2D Array that is initialised with values from a file (format: x y z). My file reads in the values correctly but when adding the z value to the matrix/2DArray, I run into a segfault and I have no idea why. It is possibly incorrect use of pointers? I still don't quite have the hang of them yet. This is my intialiser, works fine, even intialises all "z" values to 0. int** make2DArray(int rows, int columns) { int** newArray; newArray = (int**)malloc(rows*sizeof(int*)); if (newArray == NULL) { printf("out of memory for newArray.\n"); } for (int i = 0; i < rows; i++) { newArray[i] = (int*)malloc(columns*sizeof(int)); if (newArray[i] == NULL) { printf("out of memory for newArray[%d].\n", i); } } //intialise all values to 0 for (int i = 0; i < rows; i++) { for (int j = 0; j < columns; j++) { newArray[i][j] = 0; } } return newArray; } This is how I call the initialiser (and problem function). int** map = make2DArray(rows, columns); fillMatrix(&map, mapFile); And this is the problem code. void fillMatrix(int*** inMatrix, FILE* inFile) { int x, y, z; char line[100]; while(fgets(line, sizeof(line), inFile) != NULL) { sscanf(line, "%d %d %d", &x, &y, &z); *inMatrix[x][y] = z; } } From what I can gather through the use of ddd, the problem comes when y gets to 47. The map file has a max "x" value of 47 and a max "y" value of 63, I'm pretty sure I haven't got the order mixed up, so I don't know why the program is segfault-ing? I'm sure it's some newbie mistake...

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  • add space to every word's end in a string in C

    - by hlx98007
    Here I have a string: *line = "123 567 890 "; with 2 spaces at the end. I wish to add those 2 spaces to 3's end and 7's end to make it like this: "123 567 890" I was trying to achieve the following steps: parse the string into words by words list (array of strings). From upstream function I will get values of variables word_count, *line and remain. concatenate them with a space at the end. add space distributively, with left to right priority, so when a fair division cannot be done, the second to last word's end will have (no. of spaces) spaces, the previous ones will get (spaces + 1) spaces. concatenate everything together to make it a new *line. Here is a part of my faulty code: int add_space(char *line, int remain, int word_count) { if (remain == 0.0) return 0; // Don't need to operate. int ret; char arr[word_count][line_width]; memset(arr, 0, word_count * line_width * sizeof(char)); char *blank = calloc(line_width, sizeof(char)); if (blank == NULL) { fprintf(stderr, "calloc for arr error!\n"); return -1; } for (int i = 0; i < word_count; i++) { ret = sscanf(line, "%s", arr[i]); // gdb shows somehow it won't read in. if (ret != 1) { fprintf(stderr, "Error occured!\n"); return -1; } arr[i] = strcat(arr[i], " "); // won't compile. } size_t spaces = remain / (word_count * 1.0); memset(blank, ' ', spaces + 1); for (int i = 0; i < word_count - 1; i++) { arr[0] = strcat(arr[i], blank); // won't compile. } memset(blank, ' ', spaces); arr[word_count-1] = strcat(arr[word_count-1], blank); for (int i = 1; i < word_count; i++) { arr[0] = strcat(arr[0], arr[i]); } free(blank); return 0; } It is not working, could you help me find the parts that do not work and fix them please? Thank you guys.

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  • Picking good first estimates for Goldschmidt division

    - by Mads Elvheim
    I'm calculating fixedpoint reciprocals in Q22.10 with Goldschmidt division for use in my software rasterizer on ARM. This is done by just setting the nominator to 1, i.e the nominator becomes the scalar on the first iteration. To be honest, I'm kind of following the wikipedia algorithm blindly here. The article says that if the denominator is scaled in the half-open range (0.5, 1.0], a good first estimate can be based on the denominator alone: Let F be the estimated scalar and D be the denominator, then F = 2 - D. But when doing this, I lose a lot of precision. Say if I want to find the reciprocal of 512.00002f. In order to scale the number down, I lose 10 bits of precision in the fraction part, which is shifted out. So, my questions are: Is there a way to pick a better estimate which does not require normalization? Also, is it possible to pre-calculate the first estimates so the series converges faster? Right now, it converges after the 4th iteration on average. On ARM this is about ~50 cycles worst case, and that's not taking emulation of clz/bsr into account, nor memory lookups. Here is my testcase. Note: The software implementation of clz on line 13 is from my post here. You can replace it with an intrinsic if you want. #include <stdio.h> #include <stdint.h> const unsigned int BASE = 22ULL; static unsigned int divfp(unsigned int val, int* iter) { /* Nominator, denominator, estimate scalar and previous denominator */ unsigned long long N,D,F, DPREV; int bitpos; *iter = 1; D = val; /* Get the shift amount + is right-shift, - is left-shift. */ bitpos = 31 - clz(val) - BASE; /* Normalize into the half-range (0.5, 1.0] */ if(0 < bitpos) D >>= bitpos; else D <<= (-bitpos); /* (FNi / FDi) == (FN(i+1) / FD(i+1)) */ /* F = 2 - D */ F = (2ULL<<BASE) - D; /* N = F for the first iteration, because the nominator is simply 1. So don't waste a 64-bit UMULL on a multiply with 1 */ N = F; D = ((unsigned long long)D*F)>>BASE; while(1){ DPREV = D; F = (2<<(BASE)) - D; D = ((unsigned long long)D*F)>>BASE; /* Bail when we get the same value for two denominators in a row. This means that the error is too small to make any further progress. */ if(D == DPREV) break; N = ((unsigned long long)N*F)>>BASE; *iter = *iter + 1; } if(0 < bitpos) N >>= bitpos; else N <<= (-bitpos); return N; } int main(int argc, char* argv[]) { double fv, fa; int iter; unsigned int D, result; sscanf(argv[1], "%lf", &fv); D = fv*(double)(1<<BASE); result = divfp(D, &iter); fa = (double)result / (double)(1UL << BASE); printf("Value: %8.8lf 1/value: %8.8lf FP value: 0x%.8X\n", fv, fa, result); printf("iteration: %d\n",iter); return 0; }

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  • Weird behavior of fork() and execvp() in C

    - by ron
    After some remarks from my previous post , I made the following modifications : int main() { char errorStr[BUFF3]; while (1) { int i , errorFile; char *line = malloc(BUFFER); char *origLine = line; fgets(line, 128, stdin); // get a line from stdin // get complete diagnostics on the given string lineData info = runDiagnostics(line); char command[20]; sscanf(line, "%20s ", command); line = strchr(line, ' '); // here I remove the command from the line , the command is stored in "commmand" above printf("The Command is: %s\n", command); int currentCount = 0; // number of elements in the line int *argumentsCount = &currentCount; // pointer to that // get the elements separated char** arguments = separateLineGetElements(line,argumentsCount); printf("\nOutput after separating the given line from the user\n"); for (i = 0; i < *argumentsCount; i++) { printf("Argument %i is: %s\n", i, arguments[i]); } // here we call a method that would execute the commands pid_t pid ; if (-1 == (pid = fork())) { sprintf(errorStr,"fork: %s\n",strerror(errno)); write(errorFile,errorStr,strlen(errorStr + 1)); perror("fork"); exit(1); } else if (pid == 0) // fork was successful { printf("\nIn son process\n"); // if (execvp(arguments[0],arguments) < 0) // for the moment I ignore this line if (execvp(command,arguments) < 0) // execute the command { perror("execvp"); printf("ERROR: execvp failed\n"); exit(1); } } else // parent { int status = 0; pid = wait(&status); printf("Process %d returned with status %d.", pid, status); } // print each element of the line for (i = 0; i < *argumentsCount; i++) { printf("Argument %i is: %s\n", i, arguments[i]); } // free all the elements from the memory for (i = 0; i < *argumentsCount; i++) { free(arguments[i]); } free(arguments); free(origLine); } return 0; } When I enter in the Console : ls out.txt I get : The Command is: ls execvp: No such file or directory In son process ERROR: execvp failed Process 4047 returned with status 256.Argument 0 is: > Argument 1 is: out.txt So I guess that the son process is active , but from some reason the execvp fails . Why ? Regards REMARK : The ls command is just an example . I need to make this works with any given command . EDIT 1 : User input : ls > qq.out Program output : The Command is: ls Output after separating the given line from the user Argument 0 is: > Argument 1 is: qq.out In son process >: cannot access qq.out: No such file or directory Process 4885 returned with status 512.Argument 0 is: > Argument 1 is: qq.out

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  • Generating 2-dimensional vla ends in segmentation fault

    - by Framester
    Hi, further developing the code from yesterday (seg fault caused by malloc and sscanf in a function), I tried with the help of some tutorials I found on the net to generate a 2-dim vla. But I get a segmentation fault at (*data)[i][j]=atof(p);. The program is supposed to read a matrix out of a text file and load it into a 2d array (cols 1-9) and a 1D array (col 10) [Example code] #include<stdio.h> #include<stdlib.h> #include<math.h> #include<string.h> const int LENGTH = 1024; void read_data(float ***data, int **classes, int *nrow,int *ncol, char *filename){ FILE *pfile = NULL; char line[LENGTH]; if(!( pfile=fopen(filename,"r"))){ printf("Error opening %s.", filename); exit(1); } int numlines=0; int numcols=0; char *p; fgets(line,LENGTH,pfile); p = strtok (line," "); while (p != NULL){ p = strtok (NULL, ", "); numcols++; } while(fgets(line,LENGTH,pfile)){ numlines++; } rewind(pfile); int numfeats=numcols-1; *data=(float**) malloc(numlines*sizeof(float*)); *classes=(int *)malloc(numlines*sizeof(int)); if(*classes == NULL){ printf("\nOut of memory."); exit(1); } int i=0; while(fgets(line,LENGTH,pfile)){ p = strtok (line," "); for(int j=0;j<numfeats;j++) { (data)[i]=malloc(numfeats*sizeof(float)); printf("%i ",i); (*data)[i][j]=atof(p); p = strtok (NULL, ", "); } (*classes)[i]=atoi(p); i++; } fclose(pfile); *nrow=numlines; *ncol=numfeats; } int main() { char *filename="somedatafile.txt"; float **data2; int *classes2; int r,c; read_data(&data2,&classes2, &r, &c,filename) ; for(int i=0;i<r;i++){ printf("\n"); for(int j=0;j<c;j++){ printf("%f",data2[i][j]); } } return 1; } [Content of somedatafile.txt] 50 21 77 0 28 0 27 48 22 2 55 0 92 0 0 26 36 92 56 4 53 0 82 0 52 -5 29 30 2 1 37 0 76 0 28 18 40 48 8 1 37 0 79 0 34 -26 43 46 2 1 85 0 88 -4 6 1 3 83 80 5 56 0 81 0 -4 11 25 86 62 4 55 -1 95 -3 54 -4 40 41 2 1 53 8 77 0 28 0 23 48 24 4 37 0 101 -7 28 0 64 73 8 1 ...

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  • flex and bison: wrong output

    - by user2972227
    I am doing a homework using flex and bison to make a complex number calculator. But my program cannot give a correct output. .lex file: %option noyywrap %{ #include<stdio.h> #include<stdlib.h> #include "complex_cal.h" #define YYSTYPE complex #include "complex_cal.tab.h" void RmWs(char* str); %} /* Add your Flex definitions here */ /* Some definitions are already provided to you*/ ws [ \t]+ digits [0-9] number (0|[1-9]+{digits}*)\.?{digits}* im [i] complexnum {ws}*[-]*{ws}*{number}{ws}*[+|-]{ws}*{number}{ws}*{im}{ws}* op [-+*/()] %% {complexnum} {RmWs(yytext); sscanf(yytext,"%lf %lf",&(yylval.real),&(yylval.img)); return CNUMBER;} {ws} /**/ {op} return *yytext; %% /* function provided to student to remove */ /* all the whitespaces from a string. */ void RmWs(char* str){ int i=0,j=0; char temp[strlen(str)+1]; strcpy(temp,str); while (temp[i]!='\0'){ while (temp[i]==' '){i++;} str[j]=temp[i]; i++; j++; } str[j]='\0'; } .y file: %{ #include <stdio.h> #include <stdlib.h> #include "complex_cal.h" /* prototypes of the provided functions */ complex complex_add (complex, complex); complex complex_sub (complex, complex); complex complex_mul (complex, complex); complex complex_div (complex, complex); /* prototypes of the provided functions */ int yylex(void); int yyerror(const char*); %} %token CNUMBER %left '+' '-' %left '*' '/' %nonassoc '(' ')' %% /* start: Add your grammar rules and actions here */ complexexp: complexexp '+' complexexpmultidiv {$$=complex_add($1, $3);} | complexexp '-' complexexpmultidiv {$$=complex_sub($1, $3);} | complexexpmultidiv {$$.real=$1.real;$$.img=$1.img;} ; complexexpmultidiv: complexexpmultidiv '*' complexsimple {$$=complex_mul($1, $3);} | complexexpmultidiv '/' complexsimple {$$=complex_div($1, $3);} | complexsimple {$$.real=$1.real;$$.img=$1.img;} ; complexsimple: '(' complexexp ')' {$$.real=$2.real;$$.img=$2.img;} | '(' CNUMBER ')' {$$.real=$2.real;$$.img=$2.img;} ; /* end: Add your grammar rules and actions here */ %% int main(){ return yyparse(); } int yyerror(const char* s){ printf("%s\n", s); return 0; } /* function provided to do complex addition */ /* input : complex numbers c1, c2 */ /* output: nothing */ /* side effect : none */ /* return value: result of addition in c3 */ complex complex_add (complex c1, complex c2){ /* c1 + c2 */ complex c3; c3.real = c1.real + c2.real; c3.img = c1.img + c2.img; return c3; } /* function provided to do complex subtraction */ /* input : complex numbers c1, c2 */ /* output: nothing */ /* side effect : none */ /* return value: result of subtraction in c3 */ complex complex_sub (complex c1, complex c2){ /* c1 - c2 */ complex c3; c3.real = c1.real - c2.real; c3.img = c1.img - c2.img; return c3; } /* function provided to do complex multiplication */ /* input : complex numbers c1, c2 */ /* output: nothing */ /* side effect : none */ /* return value: result of multiplication in c3 */ complex complex_mul (complex c1, complex c2){ /* c1 * c2 */ complex c3; c3.real = c1.real*c2.real - c1.img*c2.img; c3.img = c1.img*c2.real + c1.real*c2.img; return c3; } /* function provided to do complex division */ /* input : complex numbers c1, c2 */ /* output: nothing */ /* side effect : none */ /* return value: result of c1/c2 in c3 */ complex complex_div (complex c1, complex c2){ /* c1 / c2 (i.e. c1 divided by c2 ) */ complex c3; double d; /*divisor calculation using the conjugate of c2*/ d = c2.real*c2.real + c2.img*c2.img; c3.real = (c1.real*c2.real + c1.img*c2.img)/d; c3.img = (c1.img*c2.real - c1.real*c2.img)/d; return c3; } .h file: #include <string.h> /* struct for holding a complex number */ typedef struct { double real; double img; } complex; /* define the return type of FLEX */ #define YYSTYPE complex Script for compiling the file: bison -d -v complex_cal.y flex -ocomplex_cal.lex.yy.c complex_cal.lex gcc -o complex_cal complex_cal.lex.yy.c complex_cal.tab.c ./complex_cal Some correct sample run of the program: input:(5+6i)*(6+1i) output:24.000000+41.000000i input:(7+8i)/(-3-4i)*(5+7i) output:-11.720000-14.040000i input:(7+8i)/((-3-4i)*(5+7i)) output:-0.128108+0.211351i But when I run this program, the program only give an output which is identical to my input. For example, when I input (5+6i)(6+1i), it just gives (5+6i)(6+1i). Even if I input any other things, for example, input "abc" it just gives "abc" and is not syntax error. I don't know where the problem is and I hope to know how to solve it.

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  • Using glDrawElements does not draw my .obj file

    - by Hallik
    I am trying to correctly import an .OBJ file from 3ds Max. I got this working using glBegin() & glEnd() from a previous question on here, but had really poor performance obviously, so I am trying to use glDrawElements now. I am importing a chessboard, its game pieces, etc. The board, each game piece, and each square on the board is stored in a struct GroupObject. The way I store the data is like this: struct Vertex { float position[3]; float texCoord[2]; float normal[3]; float tangent[4]; float bitangent[3]; }; struct Material { float ambient[4]; float diffuse[4]; float specular[4]; float shininess; // [0 = min shininess, 1 = max shininess] float alpha; // [0 = fully transparent, 1 = fully opaque] std::string name; std::string colorMapFilename; std::string bumpMapFilename; std::vector<int> indices; int id; }; //A chess piece or square struct GroupObject { std::vector<Material *> materials; std::string objectName; std::string groupName; int index; }; All vertices are triangles, so there are always 3 points. When I am looping through the faces f section in the obj file, I store the v0, v1, & v2 in the Material-indices. (I am doing v[0-2] - 1 to account for obj files being 1-based and my vectors being 0-based. So when I get to the render method, I am trying to loop through every object, which loops through every material attached to that object. I set the material information and try and use glDrawElements. However, the screen is black. I was able to draw the model just fine when I looped through each distinct material with all the indices associated with that material, and it drew the model fine. This time around, so I can use the stencil buffer for selecting GroupObjects, I changed up the loop, but the screen is black. Here is my render loop. The only thing I changed was the for loop(s) so they go through each object, and each material in the object in turn. void GLEngine::drawModel() { glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); // Vertex arrays setup glEnableClientState( GL_VERTEX_ARRAY ); glVertexPointer(3, GL_FLOAT, model.getVertexSize(), model.getVertexBuffer()->position); glEnableClientState( GL_NORMAL_ARRAY ); glNormalPointer(GL_FLOAT, model.getVertexSize(), model.getVertexBuffer()->normal); glClientActiveTexture( GL_TEXTURE0 ); glEnableClientState( GL_TEXTURE_COORD_ARRAY ); glTexCoordPointer(2, GL_FLOAT, model.getVertexSize(), model.getVertexBuffer()->texCoord); glUseProgram(blinnPhongShader); objects = model.getObjects(); // Loop through objects... for( int i=0 ; i < objects.size(); i++ ) { ModelOBJ::GroupObject *object = objects[i]; // Loop through materials used by object... for( int j=0 ; j<object->materials.size() ; j++ ) { ModelOBJ::Material *pMaterial = object->materials[j]; glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, pMaterial->ambient); glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, pMaterial->diffuse); glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, pMaterial->specular); glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, pMaterial->shininess * 128.0f); // Draw faces, letting OpenGL loop through them glDrawElements( GL_TRIANGLES, pMaterial->indices.size(), GL_UNSIGNED_INT, &pMaterial->indices ); } } if (model.hasNormals()) glDisableClientState(GL_NORMAL_ARRAY); if (model.hasTextureCoords()) { glClientActiveTexture(GL_TEXTURE0); glDisableClientState(GL_TEXTURE_COORD_ARRAY); } if (model.hasPositions()) glDisableClientState(GL_VERTEX_ARRAY); glBindTexture(GL_TEXTURE_2D, 0); glUseProgram(0); glDisable(GL_BLEND); } I don't know what I am missing that's important. If it's also helpful, here is where I read a 'f' face line and store the info in the obj importer in the pMaterial-indices. else if (sscanf(buffer, "%d/%d/%d", &v[0], &vt[0], &vn[0]) == 3) // v/vt/vn { fscanf(pFile, "%d/%d/%d", &v[1], &vt[1], &vn[1]); fscanf(pFile, "%d/%d/%d", &v[2], &vt[2], &vn[2]); v[0] = (v[0] < 0) ? v[0] + numVertices - 1 : v[0] - 1; v[1] = (v[1] < 0) ? v[1] + numVertices - 1 : v[1] - 1; v[2] = (v[2] < 0) ? v[2] + numVertices - 1 : v[2] - 1; currentMaterial->indices.push_back(v[0]); currentMaterial->indices.push_back(v[1]); currentMaterial->indices.push_back(v[2]); Again, this worked drawing it all together only separated by materials, so I haven't changed code anywhere else except added the indices to the materials within objects, and the loop in the draw method. Before everything was showing up black, now with the setup as above, I am getting an unhandled exception write violation on the glDrawElements line. I did a breakpoint there, and there are over 600 elements in the pMaterial-indices array, so it's not empty, it has indices to use. When I set the glDrawElements like this, it gives me the black screen but no errors glDrawElements( GL_TRIANGLES, pMaterial->indices.size(), GL_UNSIGNED_INT, &pMaterial->indices[0] ); I have also tried adding this when I loop through the faces on import if ( currentMaterial->startIndex == -1 ) currentMaterial->startIndex = v[0]; currentMaterial->triangleCount++; And when drawing... //in draw method glDrawElements( GL_TRIANGLES, pMaterial->triangleCount * 3, GL_UNSIGNED_INT, model.getIndexBuffer() + pMaterial->startIndex );

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