Format

Builds a String from a format string and a list of values.

Module: Std

Signature

func Format(fmt: char8[], args: Display...) -> String;

Parameters

Name	Type	Description
fmt	char8[]	The format string. Each {} is replaced by an argument.
args	Display...	Values to substitute, in order. Any Display type.

Returns

String — a new string with each {} placeholder in fmt replaced by the corresponding argument's ToString() value.

Description

Format walks the format string and replaces each {} placeholder, in order, with the next argument rendered through its Display implementation. Text outside placeholders is copied verbatim. Arguments beyond the number of placeholders are ignored; placeholders beyond the number of arguments are left empty.

WARNING

Format writes into a fixed 1024-byte buffer, so output longer than 1024 bytes is truncated. For building large strings incrementally, use StringBuilder.

Example

import Std::Format;
import Std::Io::PrintLine;

func Main() -> int {
    let x = 3;
    let y = 4;
    let s = Format("point = ({}, {})", x, y);
    PrintLine(s);                 // point = (3, 4)
    return 0;
}

See also

• Display — the interface that makes a type formattable
• Print — format and write to standard output in one call
• StringBuilder — assemble large strings without the size limit