Thread: 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.

Thanks you guys.