1. To make the program easier to read， which in turn makes it easier to maintain later.

　　3. It is easier to see what a named constant represents， if it is well named， than a literal constant，

　　which merely displays its value.

　　4. “%d %s %g\n”

　　6. The programmer can put in subscript checks where they are needed; in places where the subscript is already known to be correct （for example， from having been checked earlier）， there is no

　　overhead expended in checking it again. But the real reason they are omitted is the fact that subscripts are implemented as pointer expressions， which are described in Chapter 8

　　7. More characters would be copied than are actually needed; however， the output_col would be

　　updated properly， so the next range of characters would be copied into the output array at the

　　proper place， replacing any extra characters from the preceding operation. The only potential

　　problem is that the unbounded strcpy might copy more characters into the output array than it

　　has room to hold， destroying some other variables.