Why does my while >0 go past it into negative numbers?

Code:

---

#include  int main () {      FILE * pfile;    unsigned long long bytesremaining =0;    unsigned long long remain = 0;    char name[150] = "";    printf("enter the file name and path\n");    gets(name);      pfile = fopen (name,"rb");      if (pfile==NULL)        perror ("Error opening file");    else    {        fseeko64 (pfile, 0, SEEK_END);        remain = ftello64 (pfile);        bytesremaining=remain;        printf(" bytes left =%I64d\n",bytesremaining);        fclose (pfile);        printf ("\nFile:\n%s\ncontains %I64d bytes:\n", name, remain);        while (bytesremaining >0)        {            printf("bytes remaining = %I64d\n" , bytesremaining);            bytesremaining =bytesremaining-8;          }        break;    }    return 0; }

---

Thanks

it is not letting me edit my post it should be

Code:

---

#include  int main () {      FILE * pfile;    unsigned long long bytesremaining =0;    unsigned long long remain = 0;    char name[150] = "";    printf("enter the file name and path\n");    gets(name);      pfile = fopen (name,"rb");      if (pfile==NULL)        perror ("Error opening file");    else    {        fseeko64 (pfile, 0, SEEK_END);        remain = ftello64 (pfile);        bytesremaining=remain;        printf(" bytes left =%I64d\n",bytesremaining);        fclose (pfile);        printf ("\nFile:\n%s\ncontains %I64d bytes:\n", name, remain);        while (bytesremaining >0)        {            printf("bytes remaining = %I64d\n" , bytesremaining);            bytesremaining =bytesremaining-8;          }        break;    }    return 0; }

---

Why is this not working?

I cannot edit my posts or reply(just quick reply)

Unless bytesremaining is a multiple of 8 such that it could reach 0 exactly, wrapping the unsigned value is practically guaranteed.

Technically printf requires the type to match the format string, so "%I64" should be "%U64". So it's not that bytesremaining is negative, you're just interpreting the very large integer it wraps around to as if it were negative.

Thanks you guys.