强制转换
unsigned int x,y;
char z;
x=0x80000001;
y=*(unsigned int*)x;
z=*(char*)x;

假设0x80000001有效可访问，上面代码有问题吗
[解决办法]
unsigned int x,y;
char z;
x=0x8001;
y=*(unsigned int*)&x;
z=*(char*)&x;