PHP: is there a way to see “invisible” characters like \n

Question

Is there a way to see invisible characters like whitespace, newlines, and other non-printing characters in a manner like print_r() ?

Reason is there is some sort of

Answer 1

To see all the invisible characters not only \r, \n etc... It's good to see json_encodeed version and everything is clear:

$str = "...";
echo json_encode($str);

Answer 2

To have an exact replication of the input string, without the surrounding " and without serialization, use this wrapper for json_encode():

substr(json_encode((string)$string), 1, -1)

It does a string casting and removes the " of the JSON standard.

Answer 3

You could probably list all the control characters out, but try this for a quick fix ?

PHP - print string with control characters

It's a simple str_replace("\n",'\n',$string) kind of fix, but you could probably adapt the solution for a function callback on the array to convert those characters.

Answer 4

You could just run your php script, and pipe it straight to hexdump -C

Answer 5

You can use the addcslashes function:

string addcslashes ( string $str, string $charlist )

which will return a string with backslashes before characters. An example would be:

<?php
echo addcslashes('foo[ ]', 'A..z');
// output:  \f\o\o\[ \]
// All upper and lower-case letters will be escaped
// ... but so will the [\]^_`
?>