Why do inconsistent lines in the C FAQ ask question 16.7?

C FAQ question 16.7: http://c-faq.com/strangeprob/ptralign.html

I have a question regarding the line:

s.i32 |= (unsigned)(*p++ << 8);

I understand how this line of code works, but I don’t understand why it is not just written like this:

s.i32 |= (long) *p++ << 8;

or

s.i32 |= (unsigned)*p++ << 8; 

Why is that?

=============================

struct mystruct {
    char c;
    long int i32;
    int i16;
} s;

char buf[7];
unsigned char *p;
fread(buf, 7, 1, fp);
p = buf;

s.c = *p++;

s.i32 = (long)*p++ << 24;
s.i32 |= (long)*p++ << 16;
s.i32 |= (unsigned)(*p++ << 8); // line in question
s.i32 |= *p++;

s.i16 = *p++ << 8;
s.i16 |= *p++;

=============

Update:

It’s still not clear to me why casting should be performed after the shift operation for the line in question. Maybe, as a few words said: "This is an example, not the only opportunity."

If something is wrong with the two alternatives I proposed, add your answer. At the moment, I am choosing littleadv comment as the answer, although the order of priority for casting and <actually it didn’t bother me.

P.S. FAQ, .