Format strings in Rust

The formatting mini-language: width, precision, alignment, debug output.

fn main() {
    let name = "polars";
    let rate = 91.5_f64;
    let rows = vec![1, 2, 3];

    println!("{name:>10} | {rate:6.2}");
    println!("{:<10} | {:06.2}", "numpy", 8.0);
    println!("{rows:?}");
    println!("{:#?}", (1, "two"));
    println!("{:08b} {:#x}", 5, 255);
    println!("{}%", (rate * 10.0).round() / 10.0);
}

How it works

1. {:>8} right-aligns in eight columns, {:<} left-aligns.
2. {:.2} fixes the decimals, {:?} asks for the debug form.
3. A name inside the braces reads the variable directly.

Keywords and builtins used here

• f64
• fn
• let
• main

The run, in numbers

Lines

12

Characters to type

297

Tokens

103

Three-star pace

90 tpm

At the three-star pace of 90 tokens a minute, this run takes about 69 seconds.

Type this snippet

Step 1 of 3 in Text, step 27 of 39 in Language basics.

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