You can decipher most of them yourself.
u prefix means
- The number is the number of bits used. There's 8 bits to the byte.
_t means it's a
uint8_t is an unsigned 8 bit value, so it takes 1 byte. A
uint16_t is an unsigned 16 bit value, so it takes 2 bytes (16/8 = 2)
The only fuzzy one is
int. That is "a signed integer value at the native size for the compiler". On an 8-bit system like the ATMega chips that is 16 bits, so 2 bytes. On 32-bit systems, like the ARM based Due, it's 32 bits, so 4 bytes. Of the three it is the only one that changes.
Personally I rarely use
int and always use
uint8_t etc., since the variable type is the same no matter what architecture you compile for. When you use
int you can run into problems if you had a program that worked fine on a 32-bit ARM but then doesn't work right on an 8-bit ATMega, since the
int can only store a fraction of the range of numbers on the 8-bit system compared to the 32-bit system.