Polyglot CheatSheet - Type Casting and Type Conversion
Last Updated: 2023-03-02
Type Casting vs Type Conversion
- type conversion / type coercion: implicit, made automatically by compiler.
- type casting: explicit, done by the programmer using a cast operator.
C++
Read more: C++ Type Casting
Go
NO implicit conversion in Go: Unlike in C, in Go assignment between items of different type requires an explicit conversion. (Otherwise build would fail.)
var i int = 42
var f float64 = float64(i)
var u uint = uint(f)
i := 42
f := float64(i)
u := uint(f)
Use strconv
in the standard library to convert between strings and numbers: https://pkg.go.dev/strconv
Rust
Explicit type conversion (casting) can be performed using the as
keyword.
let integer = decimal as u8;
Saturating cast: when casting from float to int. If the floating point value exceeds the upper bound or is less than the lower bound, the returned value will be equal to the bound crossed.
// result is 255
300.0_f32 as u8
// result is 0
-100.0_f32 as u8
// result is 0
f32::NAN as u8
Use unsafe
to bypass this, but may overflow:
unsafe {
// result is 44
300.0_f32.to_int_unchecked::<u8>()
// result is 156
(-100.0_f32).to_int_unchecked::<u8>()
}
Conversions
string to char array
>>> s = "asdf"
>>> [c for c in s]
['a', 's', 'd', 'f']
int to char
>>> chr(97)
'a'
char to int
>>> ord('a')
97
int to binary
>>> format(14, 'b')
'1110'
int to hex
>>> '%#x' % 255, '%x' % 255, '%X' % 255
('0xff', 'ff', 'FF')
>>> format(255, '#x'), format(255, 'x'), format(255, 'X')
('0xff', 'ff', 'FF')
>>> f'{255:#x}', f'{255:x}', f'{255:X}'
('0xff', 'ff', 'FF')