enum kind {E_INT, E_ADD, E_TIMES}; struct Exp { enum Exp_Kind_tkind; } struct Exp_Add{ enum Exp_Kind_tkind; struct Exp *left; struct Exp *right;}
c语言中指针的强制类型转换
原文：https://www.cnblogs.com/huangmengyu/p/14190722.html
