Notice that floats in an expression are not automatically converted to double; this is a change from the original definition. In general, mathematical functions like those in <math.h> will use double precision. The main reason for using float is to save storage in large arrays, or, less often, to save time on machines where double-precision arithmetic is particularly expensive.

关于float是否转换为double? 老谭的书(C编译系统将实型常量作为双精度来处理)与K&R的书中不一样?

楼上的,那K&R的书上为何是这样写的.

The main reason for using float is to save storage in large arrays, to save time on machines where double-precision arithmetic is particularly expensive.