Write file with int[10] without ‘ ’ or ‘\n’, When I read it, there is something wrong?

Question

#define MAXN 1000000
FILE *fp1;
fp1 = fopen("num.txt", "w");
for(int i=0; i<MAXN; i++) {
    int a = rand() % (MAXN/10);
    fprintf(fp1, "%d", a);
}
...
FILE *fp2;
fp2 = fopen("num.txt", "r");
int a;
fscanf(fp2, "%d", &a);
printf("%d", a);

when I create a file, and fopen it to fp.

and I read it with fread, and I got the wrong num

(such as the first num 6414, and I got num -1182340738)

And I write it with '\n' or ' ' there is no error.

Answer 1

There doesn't appear to be a character separating the numbers, how does your parser know when one number ends and the next starts?

This I guess is your problem, it's thinking it's one very big number and overflowing to negative.

Answer 2

If your add \n,the file buffer will flush,but without \n it will not flush, so you should close first fp1 before you open the fp2.