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在代码中垂直对齐罗马数字Vertically Aligning Roman Numerals in Code

shkspr.mobi·2026-05-03 节选正文

作者在使用 PHP 处理罗马数字时遇到对齐问题：由于 Unicode 字符宽度不一致（如 'Ⅰ' 窄而 'ⅭⅯ' 宽），导致数组键值无法整齐排列。为解决此问题，他采用 CSS Flexbox 结合 `ch` 单位进行精确宽度控制，实现了视觉上的完美对齐。该方法适用于任何需要美观展示符号映射的场景。

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Terence Eden

I have a PHP function which uses Roman Numerals. It looks like this:

$romanNumerals = [
    "Ⅿ"  => 1000,
    "ⅭⅯ" => 900,
    "Ⅾ"  => 500,
    "ⅭⅮ" => 400,
    "Ⅽ"  => 100,
    "ⅩC" =>  90,
    "Ⅼ"  =>  50,
    "ⅩⅬ" => 40,
    "Ⅹ"  => 10,
    "Ⅸ"  => 9,
    "Ⅷ" => 8,
    "Ⅶ"  => 7,
    "Ⅵ"  => 6,
    "Ⅴ"   => 5,
    "Ⅳ"  => 4,
    "Ⅲ"  => 3,
    "Ⅱ"  => 2,
    "Ⅰ"   => 1
];

The problem is, the operators don't line up and the whole thing looks messy. Why? Because the Unicode Roman Numerals are not monospaced! ⅭⅯ is a different width to ⅩC and Ⅷ is only a single character! Copy the above to a text editor and see if you can get neat columns. I bet you can't!

I'm obsessed with vertically aligning my code. So how to solve this ugly problem?

The answer was simple. Assign keys to the values and then flip the array!

$romanNumerals = array_flip([
    1000 => "Ⅿ",
     900 => "ⅭⅯ",
     500 => "Ⅾ",
     400 => "ⅭⅮ",
     100 => "Ⅽ",
      90 => "ⅩC",
      50 => "Ⅼ",
      40 => "ⅩⅬ",
      10 => "Ⅹ",
       9 => "Ⅸ",
       8 => "Ⅷ",
       7 => "Ⅶ",
       6 => "Ⅵ",
       5 => "Ⅴ",
       4 => "Ⅳ",
       3 => "Ⅲ",
       2 => "Ⅱ",
       1 => "Ⅰ"
]);

There! Doesn't that look much neater!

As was written long ago:

A computer language is not just a way of getting a computer to perform operations but rather … it is a novel formal medium for expressing ideas about methodology. Thus, programs must be written for people to read, and only incidentally for machines to execute.

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