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2003-09-23 11:09:59 AM
cppbuilder35
I run the following code which calls several subroutines and
then writes intermediate data to files. After calling the
subroutine "convect" for the 47th time (that's right, the 47th)
-- I get an error "Thread stopped. Fault: access violation at
0x426440: read of address 0xffffffff" I also get a standard error message on my screen that the file hydro3.txt can't be
opened. I programmed this message into my code.
I don't know what the run time error message means. I have checked to make sure that the data I am writing is good, but if I remove the subroutine convect, evrything works fine. Ideas?
Thanks.
===============================================================
#include "includes.h"
int main()
{
FILE *fp;
// Define types
double *rho; // mass density
double *m; // momentum density
double *E; // total energy density
double *E_field; // electric field
double *phi; // potential
double *D; // doping profile
double dt; // temp{*word*203}step size
double dx; // spatial step size
double *a; // interpolation coeffcient
int i;
int j;
// Read in initial densities and electric field
D = dvector(0,N+1);
rho = dvector(0,N+1);
m = dvector(0,N+1);
E = dvector(0,N+1);
E_field = dvector(0,N+1);
phi = dvector(0,N+1);
a = dvector(0,N+1);
dx = initial(D, rho, phi, E_field, m, E, N);
if ((fp = fopen("hydro1.txt","w")) == NULL)
fprintf(stderr, "Error opening file%s.", "hydro1.txt");
for (i=0; i <= N+1 ; ++i )
fprintf(fp, "%-e\t%-e\t%-e\t%-e\t%-e\n\n", rho[i], m[i],
E[i], phi[i], E_field[i]);
fclose(fp);
for (j=1;j<=200;j++)
{
// Step One: Relaxation and Electric Field update
dt = relax(D, rho, phi, E_field, m, E, dx, a, N);
if ((fp = fopen("hydro2.txt","w")) == NULL)
fprintf(stderr, "Error opening file %
s.", "hydro2.txt");
for (i=0; i <= N+1 ; ++i )
fprintf(fp, "%-e\t%-e\t%-e\t%-e\t%-e\n\n",rho[i], m[i],
E[i], phi[i], E_field[i]);
fclose(fp);
//Step Two: Convection
convect(rho, m, E, E_field, N, dt, dx, a);
if ((fp = fopen("hydro3.txt","w")) == NULL)
fprintf(stderr, "Error opening file%
s.", "hydro3.txt");
for (i=0; i <= N+1 ; i++ )
fprintf(fp, "%-e\t%-e\t%-e\t%-e\t%-e\n\n", rho[i], m[i],
E[i], phi[i], E_field[i]);
fclose(fp);
printf("%-d\n",j);
}
return 0;
}//end main
 

cory wrote:
the cause of the non-opening.
0x426440, you will see the code that generated the error. The cause
will either be right there, before it, or elsewhere that set up the
error-waiting-to-happen.
In this particular case, it's likely cause by the fprintf() on the
invalid fp because the file couldn't be opened.
You might want to break the for(j) loop on error.
You need to handle the open-error better, including reporting
why it fails.
I think "i" goes too high in all these "for" loops.
Probably meant i<=N;
If N+1 is the number of doubles in the vector, then the index values
go from 0 to N not N+1;