learnrust/byexample/src/main.rs

fn formatted_stuff() {
    // string formatting

    // automatically casts to string (I assume that's a trait?)
    println!("{} days", 31);

    // Positional arguments
    // it should check that all are there at compile time
    println!("{0}, this is {1}. {1}, this is {0}", "Alice", "Bob");
    // it does check. this form uses macros (makes sense, really)
    // Something like "error: invalid reference to argument `2` (there are 2 arguments)"


    // named argments, too
    println!("{subject} {verb} {object}",
             object="the lazy dog",
             subject="the quick brown fox",
             verb="jumps over");

    // formatting flags are announced by ':'
    // I'm guessing 'b' means 'format as a binary number'
    println!("{} of {:b} people know binary, the other half doesn't", 1, 2);

    // "width", with padding
    println!("{number:>width$}", number=1, width=6);

    // and zero padding
    println!("{number:>0width$}", number=1, width=6);
    // this doesn't work for all characters -- just 0
    // the '$' means "look for the width in the named argument 'width'
    // can also use a positional argument
    println!("{number:>0$}", 6, number=1);
    // or an inline width
    println!("{number:>6}", number=1);


    // see https://doc.rust-lang.org/std/fmt/ for more info

}


fn main() {

    formatted_stuff();
}