Hi all, Why can't use post increment operator along with & or ++ operators ? The compiler complains that it needs an lvalue when i say ++i++ or &i++. Please let me know what happens internally with the above two expressions. thanks.
Because i++ evaluates to a number, not a variable. You can't do ++i++ or &i++ for the same reason you can't do ++5 or &5; neither make sense.
But why the following code works? Code: int main() { [SIZE=2][COLOR=#0000ff]int[/COLOR][/SIZE][SIZE=2] b=10;[/SIZE] [SIZE=2][COLOR=#0000ff]int[/COLOR][/SIZE][SIZE=2] *j=&++b;[/SIZE] [SIZE=2]++*j++;[/SIZE] [SIZE=2]}[/SIZE]
int *j=&++b; ++b in value context evaluates to b, which is an lvalue, so its address can be taken. ++*j++; Preincrement *j and postincrement j. No problem there. Except j will no longer be pointing at a valid object (it points to (&b)+4). You can always preincrement a dereferenced pointer. I guess you're misreading ++*j++ as ++(*j)++, since you seem to be comparing it with ++i++. ++*j++ is valid, but ++(*j)++ is not (you get the same error as ++i++), and is a different expression due to operator precedence. ++*j++ is equivalent to ++(*(j++)).
