将\ u表情符号字符串转换为电子邮件正文的utf-8

Question

I am having the following emoji in a PHP string variable

$emoji = "\u{1F9D1}\u{1F4AC}";
echo $emoji;

This code above will print the following emoji.

Answer 1

$foo = preg_replace('#\\\u\{(.*?)\}#', '&#x$1;', $emoji);

• \u needs to be escaped because it has special meaning in a regular expression, and since the backslash also has special meaning in PHP text literals, we need three of them here.

• { and } also have special meaning, so they need to get escaped with a single backslash.

• (.*?) matches everything (expect newlines), ? makes it ungreedy.

• I added an ; at the end in the replacement - browsers are fault tolerant when it’s missing, but it is technically required by HTML syntax.

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And the “other direction”, as requested:

$emojihtml = '🧑💬';

$bar = preg_replace('~&#x(.*?);~', '\u{$1}', $emojihtml);

(I used ~ for the regex delimiters here, because # is part of what we want to match, saves on escaping.)