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• File Segmentation when trying to write in a file

  - by user1286390

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

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• graphviz segmentation fault

  - by LucaB

  Hi I'm building a graph with many nodes, around 3000. I wrote a simple python program to do the trick with graphviz, but it gives me segmentation fault and I don't know why, if the graph is too big or if i'm missing something. The code is: #!/usr/bin/env python # Import graphviz import sys sys.path.append('..') sys.path.append('/usr/lib/graphviz') import gv # Import pygraph from pygraph.classes.graph import graph from pygraph.classes.digraph import digraph from pygraph.algorithms.searching import breadth_first_search from pygraph.readwrite.dot import write # Graph creation gr = graph() file = open('nodes.dat', 'r') line = file.readline() while line: gr.add_nodes([line[0:-1]]) line = file.readline() file.close() print 'nodes finished, beginning edges' edges = open('edges_ok.dat', 'r') edge = edges.readline() while edge: gr.add_edge((edge.split()[0], edge.split()[1])) edge = edges.readline() edges.close() print 'edges finished' print 'Drawing' # Draw as PNG dot = write(gr) gvv = gv.readstring(dot) gv.layout(gvv,'dot') gv.render(gvv,'svg','graph.svg') and it crashes at the gv.layout() call. The files are somthing like: nodes: node1 node2 node3 edges_ok: node1 node2 node2 node3

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• Why does it NOT give a segmentation violation?

  - by user198729

  The code below is said to give a segmentation violation: #include <stdio.h> #include <string.h> void function(char *str) { char buffer[16]; strcpy(buffer,str); } int main() { char large_string[256]; int i; for( i = 0; i < 255; i++) large_string[i] = 'A'; function(large_string); return 1; } It's compiled and run like this: gcc -Wall -Wextra hw.cpp && a.exe But there is nothing output. NOTE The above code indeed overwrites the ret address and so on if you really understand what's going underneath.

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• qapps runs well but breakpoint sometimes generates segmentation fault

  - by yan bellavance

  I have a qApp that generates a segmentation fault only when a breakpoint is inserted in the code (I can put it at different places) and only after 4-5 breakpoint stops. Do I have a problem with my code or is this a DBG bug. the method is part of a QThread Class. Basically what I did is i took the mandlebrot example, and have 3 instances of it in my program. So the program would look like a mainwindow that has 3 mandlebrot widgets in it, one besides the other. Is it possible that GDB doesnt support debugging qthread subclasses that are instantiated multiple times or is it thread-unsafe to do so. I dont have any problems at run-time.

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• Segmentation fault problem (C)

  - by user228938

  I have a struct named Game with an array of levels, defined like this: typedef struct { Level levels[x]; } Game; When I compile the code, if x is 1, 2 or 3, the program runs normally. If it's any other value (4, for instance), I get a segmentation fault. I'm not accessing the array anywhere. Main is something like this at the moment (commented everything except the initialization): int main (...) { Game g; return 0; } Any clue of what this might be? Thanks in advance.

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• C++ Segmentation fault in binary_function

  - by noryb009

  I'm using Visual Studio 2010 Beta 2 (also tried with NetBeans), and I'm having a segmentation fault in the following code: // One of the @link s20_3_3_comparisons comparison functors@endlink. template <class _Tp> struct less : public binary_function<_Tp, _Tp, bool> { bool operator()(const _Tp& __x, const _Tp& __y) const { return __x < __y; } //this is the problem line }; I don't know what in my program calls it, but I am trying to find out. (I think it's a map) Does anyone know what to do, or has encountered this before?

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• Segmentation fault when using files C++

  - by Popa Mihai

  I am using ubuntu 12.04. I have been trying a few IDE's for simple C++ school projects. However, with codelite, anjuta and kdevelop I encountered a problem: when I am trying to read / write in files I get segmentation fault: core dumped. I am using a basic source: #include<stdio.h> FILE*f=fopen("test.in","r"); FILE*g=fopen("test.out","w"); int main () { int a,b; fscanf(f,"%d %d",&a,&b); fprintf(g,"%d\n",a+b); fclose(f); fclose(g); return 0; } I have to say that programs with stdin/stdout work well. Thank you,

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• Segmentation fault C++ in recursive function

  - by user69514

  Why do I get a segmentation fault in my recursive function. It happens every time i call it when a value greater than 4 as a parameter #include <iostream> #include <limits> using namespace std; int printSeries(int n){ if(n==1){ return 1; } else if( n==2){ return 2; } else if( n==3){ return 3; } else if( n==4){ return printSeries(1) + printSeries(2) + printSeries(3); } else{ return printSeries(n-3) + printSeries((n-2) + printSeries(n-1)); } } int main(){ //double infinity = numeric_limits<double>::max(); for(int i=1; i<=10; i++){ cout << printSeries(i) << endl; } return 0; }

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• JVM segmentation faults due to "Invalid memory access of location"

  - by Dan

  I have a small project written in Scala 2.9.2 with unit tests written using ScalaTest. I use SBT for compiling and running my tests. Running sbt test on my project makes the JVM segfault regularly, but just compiling and running my project from SBT works fine. Here is the exact error message: Invalid memory access of location 0x8 rip=0x10959f3c9 [1] 11925 segmentation fault sbt I cannot locate a core dump anywhere, but would be happy to provide it if it can be obtained. Running java -version results in this: java version "1.6.0_37" Java(TM) SE Runtime Environment (build 1.6.0_37-b06-434-11M3909) Java HotSpot(TM) 64-Bit Server VM (build 20.12-b01-434, mixed mode) But I've also got Java 7 installed (though I was never able to actually run a Java program with it, afaik). Another issue that may be related: some of my test cases contain titles including parentheses like ( and ). SBT or ScalaTest (not sure) will consequently insert square parens in the middle of the output. For example, a test case with the name (..)..(..) might suddenly look like (..[)..](..). Any help resolving these issues is much appreciated :-) EDIT: I installed the Java 7 JDK, so now java -version shows the right thing: java version "1.7.0_07" Java(TM) SE Runtime Environment (build 1.7.0_07-b10) Java HotSpot(TM) 64-Bit Server VM (build 23.3-b01, mixed mode) This also means that I now get a more detailed segfault error and a core dump: # # A fatal error has been detected by the Java Runtime Environment: # # SIGSEGV (0xb) at pc=0x000000010a71a3e3, pid=16830, tid=19459 # # JRE version: 7.0_07-b10 # Java VM: Java HotSpot(TM) 64-Bit Server VM (23.3-b01 mixed mode bsd-amd64 compressed oops) # Problematic frame: # V [libjvm.dylib+0x3cd3e3] And the dump.

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• Why am I getting a segmentation fault?

  - by Phenom

  If I pass a value greater than 100 as the second argument to BinaryInsertionSort, I get a segmentation fault. int BinarySearch (int a[], int low, int high, int key) { int mid; if (low == high) return low; mid = low + ((high - low) / 2); if (key > a[mid]) return BinarySearch (a, mid + 1, high, key); else if (key < a[mid]) return BinarySearch (a, low, mid, key); return mid; } void BinaryInsertionSort (int a[], int n) { int ins, i, j; int tmp; for (i = 1; i < n; i++) { ins = BinarySearch (a, 0, i, a[i]); if (ins < i) { tmp = a[i]; memmove (a + ins + 1, a + ins, sizeof (int) * (i - ins)); a[ins] = tmp; } } }

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• Segmentation fault

  - by darkie15

  #include<stdio.h> #include<zlib.h> #include<unistd.h> #include<string.h> int main(int argc, char *argv[]) { char *path=NULL; size_t size; int index ; printf("\nArgument count is = %d", argc); printf ("\nThe 0th argument to the file is %s", argv[0]); path = getcwd(path, size); printf("\nThe current working directory is = %s", path); if (argc <= 1) { printf("\nUsage: ./output filename1 filename2 ..."); } else if (argc > 1) { for (index = 1; index <= argc;index++) { printf("\n File name entered is = %s", argv[index]); strcat(path,argv[index]); printf("\n The complete path of the file name is = %s", path); } } return 0; } In the above code, here is the output that I get while running the code: $ ./output test.txt Argument count is = 2 The 0th argument to the file is ./output The current working directory is = /home/welcomeuser File name entered is = test.txt The complete path of the file name is = /home/welcomeusertest.txt Segmentation fault (core dumped) Can anyone please me understand why I am getting a core dumped error? Regards, darkie

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• Getting segmentation fault after destructor

  - by therealsquiggy

  I'm making a small file reading and data validation program as part of my TAFE (a tertiary college) course, This includes checking and validating dates. I decided that it would be best done with a seperate class, rather than integrating it into my main driver class. The problem is that I'm getting a segmentation fault(core dumped) after my test program runs. Near as I can tell, the error occurs when the program terminates, popping up after the destructor is called. So far I have had no luck finding the cause of this fault, and was hoping that some enlightened soul might show me the error of my ways. date.h #ifndef DATE_H #define DATE_H #include <string> using std::string; #include <sstream> using std::stringstream; #include <cstdlib> using std::exit; #include <iostream> using std::cout; using std::endl; class date { public: explicit date(); ~date(); bool before(string dateIn1, string dateIn2); int yearsBetween(string dateIn1, string dateIn2); bool isValid(string dateIn); bool getDate(int date[], string dateIn); bool isLeapYear(int year); private: int days[]; }; #endif date.cpp #include "date.h" date::date() { days[0] = 31; days[1] = 28; days[2] = 31; days[3] = 30; days[4] = 31; days[5] = 30; days[6] = 31; days[7] = 31; days[8] = 30; days[9] = 31; days[10] = 30; days[11] = 31; } bool date::before(string dateIn1, string dateIn2) { int date1[3]; int date2[3]; getDate(date1, dateIn1); getDate(date2, dateIn2); if (date1[2] < date2[2]) { return true; } else if (date1[1] < date2[1]) { return true; } else if (date1[0] < date2[0]) { return true; } return false; } date::~date() { cout << "this is for testing only, plox delete\n"; } int date::yearsBetween(string dateIn1, string dateIn2) { int date1[3]; int date2[3]; getDate(date1, dateIn1); getDate(date2, dateIn2); int years = date2[2] - date1[2]; if (date1[1] > date2[1]) { years--; } if ((date1[1] == date2[1]) && (date1[0] > date2[1])) { years--; } return years; } bool date::isValid(string dateIn) { int date[3]; if (getDate(date, dateIn)) { if (date[1] <= 12) { int extraDay = 0; if (isLeapYear(date[2])) { extraDay++; } if ((date[0] + extraDay) <= days[date[1] - 1]) { return true; } } } else { return false; } } bool date::getDate(int date[], string dateIn) { string part1, part2, part3; size_t whereIs, lastFound; whereIs = dateIn.find("/"); part1 = dateIn.substr(0, whereIs); lastFound = whereIs + 1; whereIs = dateIn.find("/", lastFound); part2 = dateIn.substr(lastFound, whereIs - lastFound); lastFound = whereIs + 1; part3 = dateIn.substr(lastFound, 4); stringstream p1(part1); stringstream p2(part2); stringstream p3(part3); if (p1 >> date[0]) { if (p2>>date[1]) { return (p3>>date[2]); } else { return false; } return false; } } bool date::isLeapYear(int year) { return ((year % 4) == 0); } and Finally, the test program #include <iostream> using std::cout; using std::endl; #include "date.h" int main() { date d; cout << "1/1/1988 before 3/5/1990 [" << d.before("1/1/1988", "3/5/1990") << "]\n1/1/1988 before 1/1/1970 [" << d.before("a/a/1988", "1/1/1970") <<"]\n"; cout << "years between 1/1/1988 and 1/1/1998 [" << d.yearsBetween("1/1/1988", "1/1/1998") << "]\n"; cout << "is 1/1/1988 valid [" << d.isValid("1/1/1988") << "]\n" << "is 2/13/1988 valid [" << d.isValid("2/13/1988") << "]\n" << "is 32/12/1988 valid [" << d.isValid("32/12/1988") << "]\n"; cout << "blerg\n"; } I've left in some extraneous cout statements, which I've been using to try and locate the error. I thank you in advance.

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• Segmentation Fault?

  - by user336808

  Hello, when I run this program while inputting a number greater than 46348, I get a segmentation fault. For any values below it, the program works perfectly. I am using CodeBlocks 8.02 on Ubuntu 10.04 64-bit. The code is as follows: int main() { int number = 46348; vector<bool> sieve(number+1,false); vector<int> primes; sieve[0] = true; sieve[1] = true; for(int i = 2; i <= number; i++) { if(sieve[i]==false) { primes.push_back(i); int temp = i*i; while(temp <= number) { sieve[temp] = true; temp = temp + i; } } } for(int i = 0; i < primes.size(); i++) cout << primes[i] << " "; return 0; }

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• Segmentation fault in C recursive Combination (nCr)

  - by AruniRC

  PLease help me out here. The program is supposed to recursively find out the combination of two numbers. nCr = n!/ (r!(n-r)! ). I'm getting this error message when i compile it on GCC. Here's what the terminal shows: Enter two numbers: 8 4 Segmentation fault (Program exited with code:139) The code is given here: #include<stdio.h> float nCr(float, float, float); int main() { float a, b, c; printf("Enter two numbers: \n"); scanf("%f%f", &a, &b); c = nCr(a, b, a-b); printf("\n%.3f", c); return 0; } float nCr(float n, float r, float p) { if(n<1) return (1/(p*r))*(nCr(1, r-1, p-1)); if(r<1) return (n/(p*1))*(nCr(n-1, 1, p-1)); if(p<1) return (n/r)*(nCr(n-1, r-1, 1)); return ( n/(p*r) )*nCr(n-1, r-1, p-1); }

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• Testing fault tolerant code

  - by Robert

  I’m currently working on a server application were we have agreed to try and maintain a certain level of service. The level of service we want to guaranty is: if a request is accepted by the server and the server sends on an acknowledgement to the client we want to guaranty that the request will happen, even if the server crashes. As requests can be long running and the acknowledgement time needs be short we implement this by persisting the request, then sending an acknowledgement to the client, then carrying out the various actions to fulfill the request. As actions are carried out they too are persisted, so the server knows the state of a request on start up, and there’s also various reconciliation mechanisms with external systems to check the accuracy of our logs. This all seems to work fairly well, but we have difficult saying this with any conviction as we find it very difficult to test our fault tolerant code. So far we’ve come up with two strategies but neither is entirely satisfactory: Have an external process watch the server code and then try and kill it off at what the external process thinks is an appropriate point in the test Add code the application that will cause it to crash a certain know critical points My problem with the first strategy is the external process cannot know the exact state of the application, so we cannot be sure we’re hitting the most problematic points in the code. My problem with the second strategy, although it gives more control over were the fault takes, is I do not like have code to inject faults within my application, even with optional compilation etc. I fear it would be too easy to over look a fault injection point and have it slip into a production environment.

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• C lang. -- Error: Segmentation fault

  - by user233542

  I don't understand why this would give me a seg fault. Any ideas? This is the function that returns the signal to stop the program (plus the other function that is called within this): double bisect(double A0,double A1,double Sol[N],double tol,double c) { double Amid,shot; while (A1-A0 > tol) { Amid = 0.5*(A0+A1); shot = shoot(Sol, Amid, c); if (shot==2.*Pi) { return Amid; } if (shot > 2.*Pi){ A1 = Amid; } else if (shot < 2.*Pi){ A0 = Amid; } } return 0.5*(A1+A0); } double shoot(double Sol[N],double A,double c) { int i,j; /*Initial Conditions*/ for (i=0;i<buff;i++) { Sol[i] = 0.; } for (i=buff+l;i<N;i++) { Sol[i] = 2.*Pi; } Sol[buff]= 0; Sol[buff+1]= A*exp(sqrt(1+3*c)*dx); for (i=buff+2;i<buff+l;i++) { Sol[i] = (dx*dx)*( sin(Sol[i-1]) + c*sin(3.*(Sol[i-1])) ) - Sol[i-2] + 2.*Sol[i-1]; } return Sol[i-1]; } The values buff, l, N are defined using a #define statement. l = 401, buff = 50, N = 2000

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

  - by Mosh

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

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• Why I get a segmentation fault?

  - by frx08

  Why I get a segmentation fault? int main() { int height, width, step, step_mono, channels; int y, x; char str[15]; uchar *data, *data_mono; CvMemStorage* storage = cvCreateMemStorage(0); CvSeq* contour = 0; CvPoint* p; CvFont font; CvCapture *capture; IplImage *frame = 0, *mono_thres = 0; capture = cvCaptureFromAVI("source.avi"); //capture video if(!cvGrabFrame(capture)) exit(0); frame = cvRetrieveFrame(capture); //capture the first frame from video source cvNamedWindow("Result", 1); while(1){ mono_thres = cvCreateImage(cvGetSize(frame), 8, 1); height = frame -> height; width = frame -> width; step = frame -> widthStep; step_mono = mono_thres -> widthStep; channels = frame -> nChannels; data = (uchar *)frame -> imageData; data_mono = (uchar *)mono_thres -> imageData; //converts the image to a binary highlighting the lightest zone for(y=0;y < height;y++) for(x=0;x < width;x++) data_mono[y*step_mono+x*1+0] = data[y*step+x*channels+0]; cvThreshold(mono_thres, mono_thres, 230, 255, CV_THRESH_BINARY); cvFindContours(mono_thres, storage, &contour, sizeof(CvContour), CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE); //gets the coordinates of the contours and draws a circle and the coordinates in that point p = CV_GET_SEQ_ELEM(CvPoint, contour, 1); cvCircle(frame, *p, 1, CV_RGB(0,0,0), 2); cvInitFont(&font, CV_FONT_HERSHEY_PLAIN, 1.1, 1.1, 0, 1); sprintf(str, "(%d ,%d)", p->x, p->y); cvPutText(frame, str, cvPoint(p->x+5,p->y-5), &font, CV_RGB(0,0,0)); cvShowImage("Result", mono_thres); //next frame if(!cvGrabFrame(capture)) break; frame = cvRetrieveFrame(capture); if((cvWaitKey(10) & 255) == 27) break; } cvReleaseCapture(&capture); cvDestroyWindow("Result"); return 0; }

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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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• memcpy segmentation fault on linux but not os x

  - by Andre

  I'm working on implementing a log based file system for a file as a class project. I have a good amount of it working on my 64 bit OS X laptop, but when I try to run the code on the CS department's 32 bit linux machines, I get a seg fault. The API we're given allows writing DISK_SECTOR_SIZE (512) bytes at a time. Our log record consists of the 512 bytes the user wants to write as well as some metadata (which sector he wants to write to, the type of operation, etc). All in all, the size of the "record" object is 528 bytes, which means each log record spans 2 sectors on the disk. The first record writes 0-512 on sector 0, and 0-15 on sector 1. The second record writes 16-512 on sector 1, and 0-31 on sector 2. The third record writes 32-512 on sector 2, and 0-47 on sector 3. ETC. So what I do is read the two sectors I'll be modifying into 2 freshly allocated buffers, copy starting at record into buf1+the calculated offset for 512-offset bytes. This works correctly on both machines. However, the second memcpy fails. Specifically, "record+DISK_SECTOR_SIZE-offset" in the below code segfaults, but only on the linux machine. Running some random tests, it gets more curious. The linux machine reports sizeof(Record) to be 528. Therefore, if I tried to memcpy from record+500 into buf for 1 byte, it shouldn't have a problem. In fact, the biggest offset I can get from record is 254. That is, memcpy(buf1, record+254, 1) works, but memcpy(buf1, record+255, 1) segfaults. Does anyone know what I'm missing? Record *record = malloc(sizeof(Record)); record->tid = tid; record->opType = OP_WRITE; record->opArg = sector; int i; for (i = 0; i < DISK_SECTOR_SIZE; i++) { record->data[i] = buf[i]; // *buf is passed into this function } char* buf1 = malloc(DISK_SECTOR_SIZE); char* buf2 = malloc(DISK_SECTOR_SIZE); d_read(ad->disk, ad->curLogSector, buf1); d_read(ad->disk, ad->curLogSector+1, buf2); memcpy(buf1+offset, record, DISK_SECTOR_SIZE-offset); memcpy(buf2, record+DISK_SECTOR_SIZE-offset, offset+sizeof(Record)-sizeof(record->data));

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• Seg Fault when using std::string on an embedded Linux platform

  - by Brad

  Hi, I have been working for a couple of days on a problem with my application running on an embedded Arm Linux platform. Unfortunately the platform precludes me from using any of the usual useful tools for finding the exact issue. When the same code is run on the PC running Linux, I get no such error. In the sample below, I can reliably reproduce the problem by uncommenting the string, list or vector lines. Leaving them commented results in the application running to completion. I expect that something is corrupting the heap, but I cannot see what? The program will run for a few seconds before giving a segmentation fault. The code is compiled using a arm-linux cross compiler: arm-linux-g++ -Wall -otest fault.cpp -ldl -lpthread arm-linux-strip test Any ideas greatly appreciated. #include <stdio.h> #include <vector> #include <list> #include <string> using namespace std; ///////////////////////////////////////////////////////////////////////////// class TestSeg { static pthread_mutex_t _logLock; public: TestSeg() { } ~TestSeg() { } static void* TestThread( void *arg ) { int i = 0; while ( i++ < 10000 ) { printf( "%d\n", i ); WriteBad( "Function" ); } pthread_exit( NULL ); } static void WriteBad( const char* sFunction ) { pthread_mutex_lock( &_logLock ); printf( "%s\n", sFunction ); //string sKiller; // <----------------------------------Bad //list<char> killer; // <----------------------------------Bad //vector<char> killer; // <----------------------------------Bad pthread_mutex_unlock( &_logLock ); return; } void RunTest() { int threads = 100; pthread_t _rx_thread[threads]; for ( int i = 0 ; i < threads ; i++ ) { pthread_create( &_rx_thread[i], NULL, TestThread, NULL ); } for ( int i = 0 ; i < threads ; i++ ) { pthread_join( _rx_thread[i], NULL ); } } }; pthread_mutex_t TestSeg::_logLock = PTHREAD_MUTEX_INITIALIZER; int main( int argc, char *argv[] ) { TestSeg seg; seg.RunTest(); pthread_exit( NULL ); }

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• Best Practices of fault toleration and reliability for scheduled tasks or services

  - by user177883

  I have been working on many applications which run as windows service or scheduled tasks. Now, i want to make sure that these applications will be fault tolerant and reliable. For example; i have a service that runs every hour. if the service crashes while its operating or running, i d like the application to run again for the same period, to avoid data loss. moreover, i d like the program to report the error with details. My goal is to avoid data loss and not falling behind for running the program. I have built a class library that a user can import into a project. Library is supposed to keep information of running instance of the program, ie. program reads and writes information of running interval, running status etc. This data is stored in a database. I was curious, if there are some best practices to make the scheduled tasks/ windows services fault tolerant and reliable.

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• Segmentation fault in my C program

  - by user233542

  I don't understand why this would give me a seg fault. Any ideas? This is the function that returns the signal to stop the program (plus the other function that is called within this): double bisect(double A0,double A1,double Sol[N],double tol,double c) { double Amid,shot; while (A1-A0 > tol) { Amid = 0.5*(A0+A1); shot = shoot(Sol, Amid, c); if (shot==2.*Pi) { return Amid; } if (shot > 2.*Pi){ A1 = Amid; } else if (shot < 2.*Pi){ A0 = Amid; } } return 0.5*(A1+A0); } double shoot(double Sol[N],double A,double c) { int i,j; /*Initial Conditions*/ for (i=0;i<buff;i++) { Sol[i] = 0.; } for (i=buff+l;i<N;i++) { Sol[i] = 2.*Pi; } Sol[buff]= 0; Sol[buff+1]= A*exp(sqrt(1+3*c)*dx); for (i=buff+2;i<buff+l;i++) { Sol[i] = (dx*dx)*( sin(Sol[i-1]) + c*sin(3.*(Sol[i-1])) ) - Sol[i-2] + 2.*Sol[i-1]; } return Sol[i-1]; } The values buff, l, N are defined using a #define statement. l = 401, buff = 50, N = 2000 Here is the full code: #include <stdio.h> #include <stdlib.h> #include <math.h> #define w 10 /*characteristic width of a soliton*/ #define dx 0.05 /*distance between lattice sites*/ #define s (2*w)/dx /*size of soliton shape*/ #define l (int)(s+1) /*array length for soliton*/ #define N (int)2000 /*length of field array--lattice sites*/ #define Pi (double)4*atan(1) #define buff (int)50 double shoot(double Sol[N],double A,double c); double bisect(double A0,double A1,double Sol[N],double tol,double c); void super_pos(double antiSol[N],double Sol[N],double phi[][N]); void vel_ver(double phi[][N],double v,double c,int tsteps,double dt); int main(int argc, char **argv) { double c,Sol[N],antiSol[N],A,A0,A1,tol,v,dt; int tsteps,i; FILE *fp1,*fp2,*fp3; fp1 = fopen("soliton.dat","w"); fp2 = fopen("final-phi.dat","w"); fp3 = fopen("energy.dat","w"); printf("Please input the number of time steps:"); scanf("%d",&tsteps); printf("Also, enter the time step size:"); scanf("%lf",&dt); do{ printf("Please input the parameter c in the interval [-1/3,1]:"); scanf("%lf",&c);} while(c < (-1./3.) || c > 1.); printf("Please input the inital speed of eiter soliton:"); scanf("%lf",&v); double phi[tsteps+1][N]; tol = 0.0000001; A0 = 0.; A1 = 2.*Pi; A = bisect(A0,A1,Sol,tol,c); shoot(Sol,A,c); for (i=0;i<N;i++) { fprintf(fp1,"%d\t",i); fprintf(fp1,"%lf\n",Sol[i]); } fclose(fp1); super_pos(antiSol,Sol,phi); /*vel_ver(phi,v,c,tsteps,dt); for (i=0;i<N;i++){ fprintf(fp2,"%d\t",i); fprintf(fp2,"%lf\n",phi[tsteps][i]); }*/ } double shoot(double Sol[N],double A,double c) { int i,j; /*Initial Conditions*/ for (i=0;i<buff;i++) { Sol[i] = 0.; } for (i=buff+l;i<N;i++) { Sol[i] = 2.*Pi; } Sol[buff]= 0; Sol[buff+1]= A*exp(sqrt(1+3*c)*dx); for (i=buff+2;i<buff+l;i++) { Sol[i] = (dx*dx)*( sin(Sol[i-1]) + c*sin(3.*(Sol[i-1])) ) - Sol[i-2] + 2.*Sol[i-1]; } return Sol[i-1]; } double bisect(double A0,double A1,double Sol[N],double tol,double c) { double Amid,shot; while (A1-A0 > tol) { Amid = 0.5*(A0+A1); shot = shoot(Sol, Amid, c); if (shot==2.*Pi) { return Amid; } if (shot > 2.*Pi){ A1 = Amid; } else if (shot < 2.*Pi){ A0 = Amid; } } return 0.5*(A1+A0); } void super_pos(double antiSol[N],double Sol[N],double phi[][N]) { int i; /*for (i=0;i<N;i++) { phi[i]=0; } for (i=buffer+s;i<1950-s;i++) { phi[i]=2*Pi; }*/ for (i=0;i<N;i++) { antiSol[i] = Sol[N-i]; } /*for (i=0;i<s+1;i++) { phi[buffer+j] = Sol[j]; phi[1549+j] = antiSol[j]; }*/ for (i=0;i<N;i++) { phi[0][i] = antiSol[i] + Sol[i] - 2.*Pi; } } /* This funciton will set the 2nd input array to the derivative at the time t, for all points x in the lattice */ void deriv2(double phi[][N],double DphiDx2[][N],int t) { //double SolDer2[s+1]; int x; for (x=0;x<N;x++) { DphiDx2[t][x] = (phi[buff+x+1][t] + phi[buff+x-1][t] - 2.*phi[x][t])/(dx*dx); } /*for (i=0;i<N;i++) { ptr[i] = &SolDer2[i]; }*/ //return DphiDx2[x]; } void vel_ver(double phi[][N],double v,double c,int tsteps,double dt) { int t,x; double d1,d2,dp,DphiDx1[tsteps+1][N],DphiDx2[tsteps+1][N],dpdt[tsteps+1][N],p[tsteps+1][N]; for (t=0;t<tsteps;t++){ if (t==0){ for (x=0;x<N;x++){//inital conditions deriv2(phi,DphiDx2,t); dpdt[t][x] = DphiDx2[t][x] - sin(phi[t][x]) - sin(3.*phi[t][x]); DphiDx1[t][x] = (phi[t][x+1] - phi[t][x])/dx; p[t][x] = -v*DphiDx1[t][x]; } } for (x=0;x<N;x++){//velocity-verlet phi[t+1][x] = phi[t][x] + dt*p[t][x] + (dt*dt/2)*dpdt[t][x]; p[t+1][x] = p[t][x] + (dt/2)*dpdt[t][x]; deriv2(phi,DphiDx2,t+1); dpdt[t][x] = DphiDx2[t][x] - sin(phi[t+1][x]) - sin(3.*phi[t+1][x]); p[t+1][x] += (dt/2)*dpdt[t+1][x]; } } } So, this really isn't due to my overwriting the end of the Sol array. I've commented out both functions that I suspected of causing the problem (bisect or shoot) and inserted a print function. Two things happen. When I have code like below: double A,Pi,B,c; c=0; Pi = 4.*atan(1.); A = Pi; B = 1./4.; printf("%lf",B); B = shoot(Sol,A,c); printf("%lf",B); I get a segfault from the function, shoot. However, if I take away the shoot function so that I have: double A,Pi,B,c; c=0; Pi = 4.*atan(1.); A = Pi; B = 1./4.; printf("%lf",B); it gives me a segfault at the printf... Why!?

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• seg fault caused by malloc and sscanf in a function

  - by Framester

  Hi, I want to open a text file (see below), read the first int in every line and store it in an array, but I get an segmentation fault. I got rid of all gcc warnings, I read through several tutorials I found on the net and searched stackoverflow for solutions, but I could't make out, what I am doing wrong. It works when I have everything in the main function (see example 1), but not when I transfer it to second function (see example 2 further down). In example 2 I get, when I interpret gdb correctly a seg fault at sscanf (line,"%i",classes[i]);. I'm afraid, it could be something trivial, but I already wasted one day on it. Thanks in advance. [Example 1] Even though that works with everything in main: #include<stdio.h> #include<stdlib.h> #include<string.h> const int LENGTH = 1024; int main() { char *filename="somedatafile.txt"; int *classes; int lines; FILE *pfile = NULL; char line[LENGTH]; pfile=fopen(filename,"r"); int numlines=0; char *p; while(fgets(line,LENGTH,pfile)){ numlines++; } rewind(pfile); classes=(int *)malloc(numlines*sizeof(int)); if(classes == NULL){ printf("\nMemory error."); exit(1); } int i=0; while(fgets(line,LENGTH,pfile)){ printf("\n"); p = strtok (line," "); p = strtok (NULL, ", "); sscanf (line,"%i",&classes[i]); i++; } fclose(pfile); return 1; } [Example 2] This does not with the functionality transfered to a function: #include<stdio.h> #include<stdlib.h> #include<string.h> const int LENGTH = 1024; void read_data(int **classes,int *lines, char *filename){ FILE *pfile = NULL; char line[LENGTH]; pfile=fopen(filename,"r"); int numlines=0; char *p; while(fgets(line,LENGTH,pfile)){ numlines++; } rewind(pfile); * classes=(int *)malloc(numlines*sizeof(int)); if(*classes == NULL){ printf("\nMemory error."); exit(1); } int i=0; while(fgets(line,LENGTH,pfile)){ printf("\n"); p = strtok (line," "); p = strtok (NULL, ", "); sscanf (line,"%i",classes[i]); i++; } fclose(pfile); *lines=numlines; } int main() { char *filename="somedatafile.txt"; int *classes; int lines; read_data(&classes, &lines,filename) ; for(int i=0;i<lines;i++){ printf("\nclasses[i]=%i",classes[i]); } 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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• C++ Segementation fault in binary_function

  - by noryb009

  I'm using Visual Studio 2010 Beta 2 (also tried with NetBeans), and I'm having a segmentation fault in the following code: // One of the @link s20_3_3_comparisons comparison functors@endlink. template <class _Tp> struct less : public binary_function<_Tp, _Tp, bool> { bool operator()(const _Tp& __x, const _Tp& __y) const { return __x < __y; } //this is the problem line }; I don't know what in my program calls it, but I am trying to find out. (I think it's a map) Does anyone know what to do, or has encountered this before?

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