Segmentation Fault in C when reading a file full of ints

Question

I am simply trying to open a file and read the ints and print the array. However, a segmentation fault shows up. I am not sure what I am doing wrong.

int main (int argc, char *argv[])
{
   int size;
   int i;
   FILE* p = fopen(argv[1], "r");
   fscanf(p, "%d", &size);
   int a[size];

   for(i=0; i<size; i++)
   {
      a[i] = fscanf(p,"%d",&a[i]);

   }

   for(i=0;i<size;i++)
  {
      printf("%d", a[i]);
  }

}

Any help will be appreciated. Thanks.

Answer 1

The code looks fine, however you can add some validation to it to make sure your input is correct.

int main (int argc, char *argv[])
{
   int size=0;
   int i=0;
   int ret=0;

   // make sure arcv[1] exists:
   if (argc < 2)
   {
       printf("not enough arguments provided");
       return -1;
   }

   FILE* p = fopen(argv[1], "r");

   // make sure file exists
   if (p == 0) // or p == NULL
   {
       printf("file does not exists");
       return -1;
   }

   ret = fscanf(p, "%d", &size);
   // make sure the size is a valid number
   if (ret == EOF || ret <= 0 || size <= 0)
   {
       printf("invalid file");
       return -1;
   }
   int a[size];

   for(i=0; i<size; i++)
   {
      fscanf(p,"%d",a+i);
   }

   for(i=0;i<size;i++)
   {
      printf("%d", a[i]);
   }

}