Reference · General

float

float(any) -> float | error(str)

What it does

The value as a float. Text is parsed (a sign, digits, a point, an exponent, with spaces around them allowed); an int or a decimal becomes the nearest float; a float is itself. What cannot be a float is an error value, not a runtime error, so the result can be checked with is_err or given a default with ??.

Examples

print(float("3.5"), float(" 2 "), float("1e3"), float("+2.5"))print(float(3), float(dec("1.25")), float(1.5))

3.5 2.0 1000.0 2.53.0 1.25 1.5

Edge cases

• nan, inf and -inf are read as text: float("nan") is NaN, a float, not an error.
• Only ASCII digits and a point: a comma, a _ between digits, hex ("0x10"), binary ("0b11"), octal ("0o17") and digits in other scripts are errors, in the browser too.
• The empty string and null are errors, not 0.0: give the default with ??.
• A boolean is an error too, unlike int(true), which is 1.
• float(1) is 1.0, with type_of float, in the browser too: a whole float stays a float there, so 2.0 / 0 is inf and an int parameter refuses 2.0.

print(float("nan"), float("inf"), float("-inf"))print(float("3,5"), float("1_000"), float("0x10"))print(float(""), float(null), float(true))print(float(null) ?? 0.0, type_of(float(1)))

NaN inf -inferr("not a number: \"3,5\"") err("not a number: \"1_000\"") err("not a number: \"0x10\"")err("not a number: \"\"") err("cannot convert null to float") err("cannot convert bool to float")0.0 float

Errors

The error value says what was given. is_err sees it, ? passes it on, ?? replaces it. A page that needs an int from text uses int instead.

let x = float("x")print(is_err(x), x.error, x ?? 0.0)

true not a number: "x" 0.0

Chaining

print("1.5,2.5" | split(",") | map(float) | sum)print(["1", "x", "2.5"] | map(float) | filter((v) => !is_err(v)))

4.0[1.0, 2.5]

See also

int, dec, str, is_err, round

Edit this page on GitHub · every example's output was made by running it (tools/refcheck.mjs) · questions on Discord or r/quillo