解决方法
PC-Lint可以找到这种问题.
看看http://gimpel-online.com/MsgRef.html,错误代码947：
Subtract operator applied to pointers — An expression of the form p – q was found where both p and q are pointers. This is of special importance in cases where the maximum pointer can overflow the type that holds pointer differences. For example,suppose that the maximum pointer is 3 Gigabytes -1,and that pointer differences are represented by a long,where the maximum long is 2 Gigabytes -1. Note that both of these quantities fit within a 32 bit word. Then subtracting a small pointer from a very large pointer will produce an apparent negative value in the long representing the pointer difference. Conversely,subtracting a very large pointer from a small pointer can produce a positive quantity.
