1.2 Data Types

1.2.1 Integer Types

The following table summarises the relationship between Rust’s and C++’s integer data types:

Rust	C++	C & C++
i8	int8_t	char
i16	int16_t	short
i32	int32_t	int
i64	int64_t	long
i128
u8	uint8_t	unsigned char
u16	uint16_t	unsigned short
u32	uint32_t	unsigned int
u64	uint64_t	unsigned long
u128
isize
usize	size_t

While the equivalence between the first column and the second column always holds true, the third column depends on the platform and here I’m assuming you’re on a modern, 64-bit system.

While the relationships described in the table are always true, C++’s integer types are much more complex. The types above are fixed width integer types, and there are additional integer types whose width is dependent on the implementation. These include C-compatible ones (i.e. char, short, int, long, long long), and other C++ artifects such as int_fast16_t and int_least32_t. You can learn about them at cppreference.

1.2.2 Floating Point Numbers

For floating numbers, f32 and f64 correspond to float and double, respectively (stand for single-precision and double-precision floating point numbers).