#include<stdio.h>
int main(void){
unsigned char a=165;
unsigned char b=a*2;
printf("%d",b);
return 0;
}

unsigned char的范围是0-255，a*2=330=0x14a,超出了范围，截取低8位，b=0x4a=74,所以结果是74

周宇华 发表于 2014-4-15 17:53
unsigned char的范围是0-255，a*2=330=0x14a,超出了范围，截取低8位，b=0x4a=74,所以结果是74 ...

额 这样啊 谢谢