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
...
