C++ 程序片断：

char x = -1;
cout<< (unsigned)x << endl;
// 输出为 4294967295

x = 1;
cout<< (unsigned)x << endl;
// 输出为 1

经测试：

(unsigned)转换等效于(unsigned int)

Also:

(unsigned char)对于char值为负数的转换方式很迷惑