Segmentation fault !, program works:S

[jspri]

Hi, my program compiles but when i run it, i get segmentation fault ? can anybody help > thanks in advance.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(void)
{

float winddata[6572][15];
int undays = 0;
FILE *wind_data;

wind_data = fopen("wind_data.txt","r");

if(wind_data == NULL){
        printf("Error: can't open file.\n");
        return(1);
}
else{
        int i;
        int j;
        while(!feof(wind_data))
        {
        for(i = 0; i <6573; i++){
        for(j = 0; j <15; j++)
        {
        fscanf(wind_data, "%f", &(winddata[i][j]));
        }
        }


}
        for(i =0; i<6573; i++){
        if(winddata[i][3] < 5.828){
        undays++;
        }
        }
        fclose(wind_data);
        printf("Unproductive days %d\n", undays);
        return(0);

}

when i run it, the program displays the Unproductive days, but on a next line i get
"Segmentation fault.

[bithub]

you are accessing data outside the buffer. The buffer is declared as 6572, but your for loop goes to 6573. You get a seg fault when you try to access winddata[6572][0]

[prog-bman]

your overstepping the array bounds
This:

for(i =0; i<6573; i++)

Should be:

for(i =0; i<6572; i++)

Remeber arrays start at 0

[iwabee]

while (!feof(wind_data))
{
    for (i = 0; i < 6573; i++)
        for(j = 0; j <15; j++)
            fscanf(wind_data, "%f", &(winddata[i][j]));
}

This is some baaad code...
http://faq.cprogramming.com/cgi-bin/...&id=1043284351

[sand_man]

This is some baaad code...
http://faq.cprogramming.com/cgi-bin/...&id=1043284351

well, if we are going to get picky then

int i;
int j;

should be declared at the top with

float winddata[6572][15];
int undays = 0;
FILE *wind_data;

[quzah]

well, if we are going to get picky then

int i;
int j;

should be declared at the top with

float winddata[6572][15];
int undays = 0;
FILE *wind_data;

If we're going to get picky, it could be C99, in which case, it wouldn't matter.

Quzah.

[iwabee]

well, if we are going to get picky then

Picky? Are you on drugs or something? If wind_data.txt have even one return at the end of the file, then his code will go whole forfor loop all over again reading who knows what who knows where.

[jspri]

thanks guys

[Hammer]

well, if we are going to get picky then

int i;
int j;

should be declared at the top with

float winddata[6572][15];
int undays = 0;
FILE *wind_data;

But they are at the top.... of their own code block.

>>fscanf(wind_data, "%f", &(winddata[i][j]));
Always check the return code from these type of functions, to make sure they worked correctly.

>>if(winddata[i][3] < 5.828)
A word of warning:
http://www.cygnus-software.com/paper...ringfloats.htm