fseek() broken under Windows?

Code:

---

#include <stdio.h>

int main()
{
    FILE* fp = fopen("main.c", "r");
    fputc(fgetc(fp), stdout);
    fseek(fp, -1, SEEK_CUR);
    fputc(fgetc(fp), stdout);
    return 0;
}

---

Under linux, the two fgetc() will return the same character "#". But under Windows the second fgetc() returns EOF. Why is that happen?

BTW, if I change the code to fseek(fp, 0, SEEK_CUR), Linux returns two different characters "#" and "i" while windows returns two "#".

If you read the standard, you will find that "for a binary stream, the new position, measured in characters from the beginning of the
file, is obtained by adding offset to the position specified by whence", and that "for a text stream, either offset shall be zero, or offset shall be a value returned by an earlier successful call to the ftell function on a stream associated with the same file and whence shall be SEEK_SET".

You did not specify binary mode, yet you are using the file stream as if it were a binary stream. Thus, write:

Code:

---

FILE* fp = fopen("main.c", "rb");

---

and check if it works in both cases.

FILE* fp = fopen("main.c", "rb");
That works both on windows and linux. Thank you!