rust - 在 Rust 中居中动态字符串？

Question

fn main() {
    println!("{:=^50}", "Stuff");
    println!("{:=^50}", format_args!("Stuff {}", 42));
}

有人会认为它没有理由不工作，但实际上，它没有:

======================Stuff=======================
Stuff 42

Playground .

我当然可以自己做，但是有没有内置的方法来做到这一点？

Answer 1

试试 this (见 fmt):

fn main() {
    println!("{:=^50}", "Stuff");
    println!("{:=^50}", format!("Stuff {}", 42));
}

输出:

======================Stuff=======================
=====================Stuff 42=====================

试试 this :

fn main() {
    println!("{:=^50}", "Stuff");
    println!("{:=^50}", std::fmt::format(format_args!("Stuff {}", 42)));
}

输出:

======================Stuff=======================
=====================Stuff 42=====================

见 format_args :

This macro produces a value of type fmt::Arguments. This value can be passed to the macros within std::fmt for performing useful redirection. All other formatting macros (format!, write!, println!, etc) are proxied through this one. format_args!, unlike its derived macros, avoids heap allocations.

Arguments :

The format_args! macro will safely create an instance of this structure. The macro validates the format string at compile-time so usage of the write and format functions can be safely performed.

见 Display for Arguments :

impl Display for Arguments<'_> {
    fn fmt(&self, fmt: &mut Formatter<'_>) -> Result {
        write(fmt.buf, *self)
    }
}