William McBrine wrote in a message to Roy J. Tellason:

-=> Roy J. Tellason wrote to William McBrine <=-

 WM> /* get a little-endian short, return an int */
 WM> unsigned getshort(const unsigned char *x)
 WM> {
 WM>         return ((unsigned) x[1] << 8) + (unsigned) x[0];
 WM> }

 RJT> What's the effect of that "const" in there?

 WM> It indicates to the compiler that the value pointed to by x will
 WM> not be modified by getshort(). So this function can take both const
 WM> and non-const parameters. Without it, one might get a warning when
 WM> calling it with a const parameter.

So you'd use one when the function is called,  to make it match.

 WM> In practice, in this particular context, it doesn't mean much. But
 WM> I try always to add "const" to my * parameters, where possible.

I'm still not clear why that's a good thing to do.  But then,  it's been a
long time since I was studying c seriously...

---