parse_size

Parses a human-written size such as "1.5 KiB", "10MB" or "512" into a number of bytes.

The number is a non-negative decimal (a fraction is allowed, at most 18 decimal digits are used, and the result is rounded down), optionally followed by whitespace and a unit, matched without regard to case:

• none or B: bytes;
• KiB, MiB, GiB, TiB, PiB, EiB, and the single letters K, M, G, T, P, E: powers of 1024;
• KB, MB, GB, TB, PB, EB: powers of 1000.

format_size writes the binary form back.

Import

use helpers4::bytes::parse_size;

Cargo feature bytes (enabled by default). To compile only this module:

cargo add helpers4 --no-default-features --features bytes

or in Cargo.toml:

[dependencies]
helpers4 = { version = "0.0.6", default-features = false, features = ["bytes"] }

Signature

pub fn parse_size(input: &str) -> Result<u64, ParseSizeError>

Parameters

Parameter	Type	Description
input	&str	The size to parse.

Returns

Result<u64, ParseSizeError> — Ok on success, otherwise an Err: see Errors.

Errors

Returns a ParseSizeError for an empty string, something other than a number where one is expected, an unknown unit, or a size that does not fit in a u64.

Examples

use helpers4::bytes::parse_size;

assert_eq!(parse_size("1.5 KiB"), Ok(1536));
assert_eq!(parse_size("10MB"), Ok(10_000_000));
assert_eq!(parse_size("512"), Ok(512));
assert!(parse_size("ten").is_err());

Error type: ParseSizeError

Why a string could not be parsed as a size.

use helpers4::bytes::ParseSizeError;

#[non_exhaustive]
pub enum ParseSizeError {
    /// The string is empty or only whitespace.
    Empty,
    /// A number was expected but something else was found.
    ExpectedNumber {
        /// Byte offset of the offending character in the input.
        index: usize,
    },
    /// The unit is not one of the known ones (`B`, `KB`, `KiB`, `K`, ...).
    UnknownUnit {
        /// Byte offset of the unit in the input.
        index: usize,
    },
    /// The size does not fit in a `u64`.
    Overflow,
}

Source

src/bytes/parse_size.rs