Segmentation fault with fscanf in C : buffer overflow?

Question

I would like to read a file with "1 million" rows with 9 columns. The program works well if the file has at the maximum 200,000 rows, otherwise I see the following error :

Segmentation fault : core dumped

error exit code : 139

The problem is that I want to read the file such that I can read values in different columns, therefore, I can not use "fgets" which would scan the whole row. I could not find a good solution to this problem, could I get some help on this ?

Here is a snapshot of my program (omitted the definition of "y" (as seen below)) :

int main(){
int number=290000;
int k,u,i,n = 10000;
float ns_ux[number], ns_uy[number], ns_uz[number], xn[number], yn[number], zn[number];
float l[number],b[number], ns[number], xf,x0,step,s;

FILE *fp=NULL;
fp=fopen("File_new.txt","w");
printf("Enter x0, xf, no. of subintervals: ");
scanf("%f%f%d",&x0, &xf,&n); 
FILE* val= NULL;

printf("k  xn   yn  zn  int_val     tau  \n");
val=fopen("file.txt", "r");

for(u=0;u<=(number-1);u++){
   fscanf(val,"%f %f %f %f %f %f %f %f %f", &xn[u], &yn[u], &zn[u], &ns_ux[u], &ns_uy[u], &ns_uz[u], &l[u], &b[u], &ns[u]);// \t is tab
            }
    for(k=0;k<=(number-1);k++){
    step = (xf-x0)/n;
    s = y(x0,xn[k],yn[k], zn[k], ns_ux[k], ns_uy[k], ns_uz[k], l[k], b[k], ns[k]) + y(xf,xn[k],yn[k], zn[k], ns_ux[k], ns_uy[k], ns_uz[k],l[k], b[k], ns[k]);

    for(i = 1; i < n; i++){
        s += 2*y(x0+i*step,xn[k],yn[k], zn[k], ns_ux[k], ns_uy[k], ns_uz[k], l[k], b[k], ns[k] );
        }
      int_val = s*step/2; 
      fprintf(fp,"%f\t%f\t%1.7f\t%f\n",l[k],b[k],fabs(int_val),ns[k]);
}
fclose(fp);

        return 0;
}

Answer 1

int number=290000;
float ns_ux[number], ns_uy[number], ns_uz[number], xn[number], yn[number], zn[number];

Array with 290000 elements on stack may cause problem . You should allocate memory on heap using malloc .

  float *ns_ux;
  ns_ux=malloc(sizeof(float)*290000);       // like this for all and check its return

Note-

1. You have many arrays , so after allocating free each one or it may lead to memory leak.

2. Check return of fopen and fscanf in your code.

3. For safety initialize s in your program.

Answer 2

由于这些数组是在堆栈上创建的，因此您可以尝试执行ulimit -s unlimited以设置“无限”堆栈大小

Answer 3

You should use malloc as it says before and protect it.

float *arr;

arr = (float *)malloc(sizeof(float) * 290000)
if (!arr)
{
   printf("error malloc");
   exit(0);
}

Don't forget to free !