How to decode Unicode escape sequences like "\u00ed" to proper UTF-8 encoded characters?

In PHP, you can use the utf8_decode() function to decode a string that contains Unicode escape sequences.

Here's an example:

<?php

// Define a string in Unicode escape sequence
$unicode_string = "\u00e7af\u00e9 au lait";

// Convert the string from Unicode escape sequence to UTF-8 encoding
$utf8_string = json_decode('"' . $unicode_string . '"');

// Output the result
echo $utf8_string; // Output: "çafé au lait"

You can also use the mb_convert_encoding() function to achieve the same result:

<?php

// Define a string in Unicode escape sequence
$unicode_string = "\u00e7af\u00e9 au lait";

// Convert the string from Unicode escape sequence to UTF-8 encoding
$utf8_string = json_decode('"' . $unicode_string . '"');

// Convert the UTF-8 string to ISO-8859-1 encoding
$iso_string = mb_convert_encoding($utf8_string, "ISO-8859-1", "UTF-8");

// Convert the ISO-8859-1 string back to UTF-8 encoding
$utf8_string = mb_convert_encoding($iso_string, "UTF-8", "ISO-8859-1");

// Output the result
echo $utf8_string; // Output: "çafé au lait"

Both of these functions will convert the Unicode escape sequence "\u00ed" to the UTF-8 encoded character "í".