Isaac Marino Bavaresco wrote:

>> BTW I don't see 'const' being used anywhere, but I thought a const
>> byte * meant not that the pointer couldn't change, just the
>> pointer's own address didn't.  But see, there's two more questions,
>> (1) to see if I'm right, and (2) to see if the compiler got it right
>> :)
> 
> When 'const' is to the left side of the asterisk, it means that the
> element pointed by the pointer must not be changed. When the 'const'
> is to the right side of the asterisk, then the pointer value itself
> must not be changed. 
> 
> The pointer own address can't be changed, only its own content
> (address of the element pointed by it) or the content of the element
> pointed by it.

It helps to place the const somewhat unconventionally after the type and
read the type's "meaning" from right to left:

typedef uint8_t byte;

byte *p1; // (Non-const) ptr to (non-const) byte. 
// Both p1 and its target *p1 can be modified.

byte const *p2; // (Non-const) ptr to const byte. 
// The pointer p2 can be changed, but the byte *p2 can't.

byte *const p3; // Const ptr to (non-const) byte. 
// The pointer p3 can't be changed, but the byte *p3 can.

byte const *const p4; // Const ptr to const byte. 
// Neither the ptr p4 nor the byte *p4 can be changed.

Gerhard
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