C++ types

C++ has several standard, or built-in, types. They could be divided into several classes: integers, character and floating point numbers.

Integers

Integer types differ by their size in bits. There are 8 bits (char), 16 bits (short), 32 bits (int), and 64 bits (long long). Though the exact size depends on a processor architecture and compiler; in order to get the same size in all cases, one should use constant size types, like int32_t, defined in inttypes.h (cinttypes in C++) header. By default, each integer type is signed; to make them unsigned they should be prefixed by unsigned keyword.

The most common integer type in int it is 32 bits long (except for 16-bit processors, where it is 16 bits long; on 64-bit processors it is 32 bits long). You should remember that on 64-bit processors it is less than the pointer size (which is 64 bits), thus it should not be casted. In modern style programs, it is recommend to use size_t instead of unsigned int and ptrdif_t instead of int, these types are 32 bits long on 32-bit processor and or 64 bits long on 64-bit processors. This will allow to avoid unsafe cast as well as will not downgrade the perfomance on both modern and old processors.

The next type is long, on all processors it is 32 bits long including 16 bits processor (unlike int). It is not recommended for usage in modern programs (use int instead).

Type tables

Type	Size
	64-bit	32-bit	16-bit
char	8 bits	8 bits	8 bits
short	16 bits	16 bits	16 bits
int	32 bits	32 bits	16 bits
long	32 bits	32 bits	32 bits
long long	64 bits	64 bits
ptrdiff_t / size_t	64 bits	32 bits	16 bits
int8_t / uint8_t	8 bits	8 bits	8 bits
int16_t / uint16_t	16 bits	16 bits	16 bits
int32_t / uint32_t	32 bits	32 bits	32 bits
int64_t / uint64_t	64 bits	64 bits	64 bits