rust - 有没有办法在 Rust 中用 "0x"右对齐十六进制数？

Question

我正在尝试用 Rust 打印这样的东西:

Base:       0x40, length: 900
Base:     0x5500, length: 301

现在我有:

println!("Base: {:>width$x}, length: {}", 67106, 54, width=10);

Base:      10622, length: 54

有没有办法让 Rust 包含“0x”前缀？这两个不编译:

println!("Base: {:>width#$x}, length: {}", 67106, 54, width=10);
println!("Base: {:>width$#x}, length: {}", 67106, 54, width=10);

error: invalid format string: expected `'}'`, found `'#'`
 --> src/main.rs:2:29
  |
2 |     println!("Base: {:>width#$x}, length: {}", 67106, 54, width=10);
  |                     -       ^ expected `}` in format string
  |                     |
  |                     because of this opening brace
  |
  = note: if you intended to print `{`, you can escape it using `{{`

error: invalid format string: expected `'}'`, found `'#'`
 --> src/main.rs:3:30
  |
3 |     println!("Base: {:>width$#x}, length: {}", 67106, 54, width=10);
  |                     -        ^ expected `}` in format string
  |                     |
  |                     because of this opening brace
  |
  = note: if you intended to print `{`, you can escape it using `{{`

我最好的是:

println!("Base: 0x{:0>8x}, length: {}", 67106, 54);

Base: 0x00010622, length: 54

这可能没问题，但我很好奇是否有办法做到这一点。另外，我想也许这会奏效，但没有这样的运气:

println!("Base: {:>10}, length: {}", format_args!("{:#x}", 67106), 54);

Base: 0x10622, length: 54

Answer 1

println!("Base: {:>#10x}, length: {}", 0x40, 900);

您需要在宽度前加上# 来设置替代形式。查看std::fmt syntax格式的解释。

将 width 作为参数传递，将是:

println!("Base: {:>#width$x}, length: {}", 67106, 301, width=10);