Unsigned long is an unsigned long integer, which depends on the specific situation. Unsigned and signed are the same length, but the first bit is no longer used as a sign bit, so there will be one more bit in the numerical value part.

There are signed and unsigned by symbol, char, short, long and long long by length. In a 32-bit compiler, Int is equivalent to long.

Short is 16 bit, and int is generally 32 bit.

Either this book is nonsense or you are wrong. Long is 32 bits, that is, 4 bytes. Int, as I said above,

Dividing the byte after bit conversion by 8 may be different in some places, because the CPU in the past was not 8 bits 1 byte, and now that strange thing doesn't exist, 8 bits 1 byte is the de facto standard.