C语言中，调用成员变量用点还是用箭头，取决于当前的ID是指针还是结构体本身。
如：typedef struct {
float height;
float weight;
} Person;
int main(int argc, char *argv[]) {
Person jiushen;
Person *lengleng = (Person *)malloc(sizeof(Person));
//注意这里结构体指针的声明，要分配空间
jiushen.weight = 60;
jiushen.height = 175;
lengleng -> height = 165;
(*lengleng).weight = 50;
printf("%f, %f\n", jiushen.weight, lengleng->weight);
}
可以看出，对于指针lengleng,
lengleng -> weight
等价于
(*lengleng).weight
)
