std/fmt

Library guide · API index and notation

This page is generated from the bundled library in this checkout. Signatures and adjacent source comments are reproduced below; the linked guide explains usage, storage, failures, and platform support.

import "std/fmt"

Names used in signatures

Unqualified names denote this package’s types (including other source files in the same package), language built-ins, or generic parameters such as T. Qualified names use the import aliases below. These aliases belong to the library source; import a dependency yourself to use its alias in your program.

Alignment

Enum · Source

pub enum Alignment {
    Left, Right, Center
}

Sign

Enum · Source

pub enum Sign {
    NegativeOnly, Always, Space
}

FloatStyle

Enum · Source

pub enum FloatStyle {
    Fixed, Scientific
}

Options

Struct · Source

Width counts output bytes, not Unicode scalars, graphemes, or display columns. Fill must be ASCII. Numeric zero padding follows the sign. Center places an odd extra padding byte on the right. radix must be in 2..=36.

pub struct Options {
    pub width: usize
    pub fill: u8
    pub alignment: Alignment
    pub sign: Sign
    pub radix: u8
    pub uppercase: bool
    pub zero_pad: bool
}

defaults

Function · Source

pub fn defaults() -> Options

Formatter

Struct · Source

Statically dispatched byte formatting. W implements the std/io writer contract. No allocation, implicit flush, global locale, or format parser. Each failure reports total bytes emitted by this Formatter, including the failing write’s partial progress. Prior bytes are never rolled back.

pub struct Formatter<W> {
    // Private implementation fields omitted.
}

Formatter.new

Function · Source

pub fn new(sink: &mut W) -> Formatter<W> from(sink)

Formatter.written

Function · Source

pub fn written(&self) -> usize

Formatter.bytes

Function · Source

pub fn bytes(&mut self, value: &[u8]) -> void!io.Error

Formatter.string

Function · Source

pub fn string(&mut self, value: &str) -> void!io.Error

Formatter.decimal

Function · Source

Default decimal helpers also form the structural error-formatting contract.

pub fn decimal(&mut self, value: i64) -> void!io.Error

Formatter.natural

Function · Source

pub fn natural(&mut self, value: u64) -> void!io.Error

Formatter.padded_string

Function · Source

pub fn padded_string(&mut self, value: &str, options: &Options) -> void!io.Error

Formatter.boolean

Function · Source

pub fn boolean(&mut self, value: bool, options: &Options) -> void!io.Error

Formatter.codepoint

Function · Source

pub fn codepoint(&mut self, value: u32, options: &Options) -> void!io.Error

Formatter.unsigned

Function · Source

pub fn unsigned(&mut self, value: u64, options: &Options) -> void!io.Error

Formatter.signed

Function · Source

pub fn signed(&mut self, value: i64, options: &Options) -> void!io.Error

Formatter.floating

Function · Source

Precision is mandatory, 0..=324 decimal places. Scientific uses exactly precision digits after its radix point; the exponent has at least 2 digits. Round to nearest, ties to even. Preserve negative zero. Emit inf/nan (or uppercase forms); all NaNs are canonicalized to an unsigned nan spelling.

pub fn floating(&mut self, value: f64, precision: usize, style: FloatStyle, options: &Options) -> void!io.Error

FormatError

Enum · Source

Transactional decimal formatting into caller storage. Width is a minimum; values are never truncated. The full output is checked before the first write.

pub enum FormatError {
    BufferTooSmall
}

write_u32_padded

Function · Source

pub fn write_u32_padded(destination: &mut[u8], value: u32, width: usize) -> usize!FormatError

print

Function · Source

These reserved declarations lower to fixed, statically typed functions before normal checking. All output uses one Formatter and preserves io.Error counts. print/println automatically format primitives and borrow custom value places.

@compiler(print)
pub fn print<W, T>(sink: &mut W, value: T) -> usize!io.Error

println

Function · Source

@compiler(println)
pub fn println<W, T>(sink: &mut W, value: T) -> usize!io.Error

printf

Function · Source

printf requires a literal format followed by heterogeneous arguments. {} is automatic; {{ and }} escape braces. Options after ‘:’ are [[fill]align][sign][0][width][.precision][type]; see the formatting reference.

@compiler(printf)
pub fn printf<W>(sink: &mut W, format: &str) -> usize!io.Error

Codepoint

Struct · Source

A codepoint wrapper selects UTF-8 scalar rendering instead of integer output.

pub struct Codepoint {
    // Private implementation fields omitted.
}

Codepoint.format

Function · Source

pub fn format<W>(&self, output: &mut Formatter<W>) -> void!io.Error

codepoint

Function · Source

pub fn codepoint(value: u32) -> Codepoint