First of all, look at int and char, which are integer data and character data respectively. They occupy 1 and 2 bytes in the computer (TC environment), and the number of bytes occupied by different environments may be different. Unsigned int is unsigned integer data, and unsigned char is unsigned character data. The number of bytes they occupy in the computer is exactly the same as that of int and char. The difference is that the data ranges of unsigned int and int (= signed int) are different. Unsigned data is not divided into positive and negative, and the range of signed number is smaller than unsigned data, because it needs a data bit to store the sign bit. So you can know the difference between unsigned char and char! By the way, the scope of these four data types! Int (= signed int)-32768 ~+32767 unsigned int 0 ~ 65535 char (= signed char)-128 ~+127

Unsigned characters 0~255