Understanding what \u0000 is in PHP / JSON and getting rid of it

Question

I haven't a clue what is going on but I have a string inside an array. It must be a string as I have ran this on it first:

$array[0] = (string)$array[0];

If I output $array[0] to the browser in plain text it shows this:

hellothere

But if I JSON encode $array I get this:

hello\u0000there

Also, I need to separate the 'there' part (the bit after the \u0000), but this doesn't work:

explode('\u0000', $array[0]);

I don't even know what \u0000 is or how to control it in PHP.

I did see this link: Trying to find and get rid of this \u0000 from my json ...which suggests str_replacing the JSON that is generated. I can't do that (and need to separate it as mentioned above first) so I then checked Google for 'php check for backslash \0 byte' but I still can't work out what to do.

`\u` is used to escape unicode symbols, basically the unicode equivalent to `\x00`. — Havenard, Jul 06 '13 at 05:24
\u0000 is unicode. http://stackoverflow.com/questions/6058394/unicode-character-in-php-string — James P., Jul 06 '13 at 05:24

score 13 · Accepted Answer · answered Jul 06 '13 at 05:24

13

\uXXXX is the JSON Unicode escape notation (X is hexadecimal).

In this case, it means the 0 ASCII char, aka the NUL byte, to split it you can either do:

explode('\u0000', json_encode($array[0]));

Or better yet:

explode("\0", $array[0]); // PHP doesn't use the same notation as JSON

answered Jul 06 '13 at 05:24

Alix Axel

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explode("\0", $array[0]) - that's the one. None of the others worked. I'll accept the answer as soon as it allows me. Thanks – user2143356 Jul 06 '13 at 05:29
PHP does not understand \uHHHH notation within strings. – Nicholas Shanks Jul 26 '13 at 12:12
@Nicholas: Right. It does understand `\HH` however. – Alix Axel Jul 26 '13 at 19:13
...or better yet `str_replace('\0', '', $json_data)` – Mihai Stancu Apr 09 '14 at 09:14
@MihaiStancu: Yes, but that won't separate like the OP wanted. – Alix Axel Apr 09 '14 at 13:13
Using `trim` is simpler and more flexible. – Shaffe Apr 26 '18 at 17:52

score 12 · Answer 2 · answered Jul 06 '13 at 05:30

12

The string you have is "hello\0world", or "hello\x00world" whatever you prefer. If you echo it, the null symbol \0 won't be displayed, thats why you see helloworld instead, but json_encode will detect it and escape it as it does to any other special character, thats why its replaced by a visible \u0000 string.

In my way of seeing it, json is encoding the string perfectly, the \u0000 is there to do its job of reproducing the inputted string in a json encoded way. You don't have to touch its output. If you don't want that \u0000 there you should fix its input instead.

answered Jul 06 '13 at 05:30

Havenard

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How to fix the input, I have a UTF-8 encoded file - but no way I can find any null characters in there - please help – almaruf Aug 19 '16 at 11:27
@almaruf By removing the characters from the string before encoding it, of course. And yeah, null characters won't be displayed and give you the impression that they are simply not there, but at binary level they are and a `str_replace()` will be able to find and replace them. – Havenard Aug 19 '16 at 18:51

score 10 · Answer 3 · edited May 10 '14 at 12:18

10

you can simply do trim($str) without giving it a charlist

edited May 10 '14 at 12:18

Jaap

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answered May 10 '14 at 11:30

roy

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Great answer! Thanks – flangofas Feb 08 '17 at 11:41

score 3 · Answer 4 · answered Jan 28 '21 at 16:23

3

Just in case anyone need it to apply to the whole array

$data = (array)json_decode(str_replace('\u0000*\u0000', '', json_encode($data)));

answered Jan 28 '21 at 16:23

Ezequiel García

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score 2 · Answer 5 · answered Jul 06 '13 at 05:24

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\uXXXX is the unicode symbol with code XXXX (hexadecimal). For example: http://msdn.microsoft.com/en-us/library/aa664669(v=vs.71).aspx

If you really get 0000 - then it's just the char with code 0

answered Jul 06 '13 at 05:24

mishik

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score 2 · Answer 6 · answered Apr 09 '14 at 09:10

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I came across this issue today and I sorted it out by replacing \u0000 in my array with "" before sending it back to the client.

echo str_replace('\\u0000', "", json_encode($send));

answered Apr 09 '14 at 09:10

Sorin

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score 2 · Answer 7 · answered Jan 10 '20 at 19:26

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In my case I've found the symbol inside serialized Laravel job's payload json, something like s:8:"\0*\0order"; (or s:8:"\u0000*\u0000order";) which meant that serialized object's property order has visibility protected on a moment of serialization

answered Jan 10 '20 at 19:26

gorodezkiy

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score 0 · Answer 8 · edited Jul 06 '13 at 05:54

0

Try explode("\u0000", $array[0]);, making sure you use double quotes. With single quotes it's going to parse the literal 6 character value.

As others have mentioned, \u0000 is the Unicode NUL character.

edited Jul 06 '13 at 05:54

icedwater

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answered Jul 06 '13 at 05:25

cwurtz

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Except that it's `\u0000` and not `\0000`. – icedwater Jul 06 '13 at 05:35

Understanding what \u0000 is in PHP / JSON and getting rid of it

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