What's the error in this code?(C - File Handling) - c

Question

What I want to do is to write n(taken from user) elements to a file.Then read the elements again to an array and sort them and again write them in another file.
Finally open that file and display its contents.
But the code seems not to work, all syntax, grammar etc is checked what's the error??
#include<stdio.h>
struct data
{
int a,ar[100];
}e;
int main()
{ FILE *f1,*f2;
int i,j,n,t;
printf("\nEnter Array Size:");
scanf("%d",&n);
f1=fopen("Array.txt","w");
for(i=0;i<n;i++)
{ printf("\nEnter %d element:",i+1);
scanf("%d",&e.a);
fprintf(f1,"%d",e.a);
}
fflush(stdin);
fclose(f1);
rewind(f1);
i=0;
f1=fopen("Array.txt","r");
while((fscanf(f1,"%d",&e.ar[i++]))!=EOF)
{}
fclose(f1);
for(i=0;i<n;i++)
{ for(j=0;j<n-1;j++)
{ if(e.ar[j]>e.ar[j+1])
{ t=e.ar[j];
e.ar[j]=e.ar[j+1];
e.ar[j+1]=t;
}
}
}
f2=fopen("Sort.txt","w");
i=0;
while((fprintf(f2,"%d",e.ar[i]))!=EOF)
{ i++;}
fclose(f2);
f2=fopen("Sort.txt","r");
while((fscanf(f2,"%d",&e.a))!=EOF)
{ printf("%d ",e.a);
}
fclose(f2);
return 0;
}

Answer 1

So you want to know the error? I found a HUGE one.
As I was running your program, I have determined a segmentation fault occurs after this line:
f2=fopen("Sort.txt","w");
The major error here is that you opened a file for writing data to it, but you're making a rather confusing loop.
This is your code:
i=0;
while((fprintf(f2,"%d",e.ar[i]))!=EOF)
{ i++;}
In the state it is in, the value of i will exceed the upper bound value of your ar int array. You set the upper bound value to 100, but in the while loop, it will run endlessly until segmentation fault happens (when i goes past 100) because fprintf will never return an EOF (according to what the linux manual on fprintf claims).
What I would suggest instead is this:
for(i=0;i<n;i++){
fprintf(f2,"%d",e.ar[i]);
}
where n is the number of elements to finally print (as indicated by user at beginning of the program).