PHP Escaped special characters to html - php

Question

I have string that looks like this "v\u00e4lkommen till mig" that I get after doing utf8_encode() on the string.
I would like that string to become
välkommen till mig
where the character
\u00e4 = ä = ä
How can I achive this in PHP?

Answer 1

Do not use utf8_(de|en)code. It just converts from UTF8 to ISO-8859-1 and back. ISO 8859-1 does not provide the same characters as ISO-8859-15 or Windows1252, which are the most used encodings (besides UTF-8). Better use mb_convert_encoding.
"v\u00e4lkommen till mig" > This string looks like a JSON encoded string which IS already utf8 encoded. The unicode code positiotion of "ä" is U+00E4 >> \u00e4.
Example
<?php
header('Content-Type: text/html; charset=utf-8');
$json = '"v\u00e4lkommen till mig"';
var_dump(json_decode($json)); //It will return a utf8 encoded string "välkommen till mig"
What is the source of this string?
There is no need to replace the ä with its HTML representation ä, if you print it in a utf8 encoded document and tell the browser the used encoding. If it is necessary, use htmlentities:
<?php
$json = '"v\u00e4lkommen till mig"';
$string = json_decode($json);
echo htmlentities($string, ENT_COMPAT, 'UTF-8');

Answer 2

Edit: Since you want to keep HTML characters, and I now think your source string isn't quite what you posted (I think it is actual unicode, rather than containing \unnnn as a string), I think your best option is this:
$html = str_replace( str_replace( str_replace( htmlentities( $whatever ), '<', '<' ), '>', '>' ), '&', '&' );
(note: no call to utf8-decode)
Original answer:
There is no direct conversion. First, decode it again:
$decoded = utf8_decode( $whatever );
then encode as HTML:
$html = htmlentities( $decoded );
and of course you can do it without a variable:
$html = htmlentities( utf8_decode( $whatever ) );
http://php.net/manual/en/function.utf8-decode.php
http://php.net/manual/en/function.htmlentities.php
To do this by regular expression (not recommended, likely slower, less reliable), you can use the fact that HTML supports &#xnnnn; constructs, where the nnnn is the same as your existing \unnnn values. So you can say:
$html = preg_replace( '/\\\\u([0-9a-f]{4})/i', '&#x$1;', $whatever )

Answer 3

The html_entity_decode worked for me.
$json = '"v\u00e4lkommen till mig"';
echo $decoded = html_entity_decode( json_decode($json) );