tYSR20

Chapter 9: Taking a Second Look at C++ Pointers 127Table 9-2Adding OffsetsOffset Result Is the Address of+ 0 0x110 charArray[0]+ 1 0x111 charArray[1]+ 2 0x112 charArray[2]... ... ...+ n 0x110 + n charArray[n]The addition of an offset to a pointer is similar to applying an index to anarray.Thus, ifchar* ptr = &charArray[0];then*(ptr + n) ← corresponds with → charArray[n]Because * has higher precedence than addition, * ptr + n adds n to thecharacter that ptr points to. The parentheses are needed to force the additionto occur before the indirection. The expression *(ptr + n) retrievesthe character pointed at by the pointer ptr plus the offset n.In fact, the correspondence between the two forms of expression is so strongthat C++ considers array[n] nothing more than a simplified version of *(ptr+ n), where ptr points to the first element in array.array[n] -- C++ interprets as → *(&array[0] + n)In order to complete the association, C++ takes a second shortcut. If givenchar charArray[20];charArray is defined as &charArray[0];.That is, the name of an array without a subscript present is the address ofthe array itself. Thus, you can further simplify the association toarray[n] --> C++ interprets as --> *(array + n)