PHP json_encode encoding numbers as strings

Question

I am having one problem with the PHP json_encode function. It encodes numbers as strings (e.g. array('id' => 3 becomes "{ ["id": "3", ...) When js encounters these values, it interprets them as strings and numeric operations fail on them. Does anyone know some way to prevent json_encode from encoding numbers as strings? Thank you!

Answer 1

json_encode serializes some data structure in JSON format to be send across the network. Therefore all content will be of the type string. Just like when you receive some parameter from $_POST or $_GET.

If you have to make numeric operations on the values sent, just convert them to int first (with the intval() function in PHP or parseInt() in Javascript) and then execute the operations.

Answer 2

Well, PHP json_encode() returns a string.

You can use parseFloat() or parseInt() in the js code though:

parseFloat('122.5'); // returns 122.5
parseInt('22'); // returns 22
parseInt('22.5'); // returns 22

Answer 3

I've done a very quick test :

$a = array(
    'id' => 152,
    'another' => 'test',
    'ananother' => 456,
);
$json = json_encode($a);
echo $json;

This seems to be like what you describe, if I'm not mistaken ?

And I'm getting as output :

{"id":152,"another":"test","ananother":456}

So, in this case, the integers have not been converted to string.

Still, this might be dependant of the version of PHP we are using : there have been a couple of json_encode related bugs corrected, depending on the version of PHP...

This test has been made with PHP 5.2.6 ; I'm getting the same thing with PHP 5.2.9 and 5.3.0 ; I don't have another 5.2.x version to test with, though :-(

Which version of PHP are you using ? Or is your test-case more complex than the example you posted ?

Maybe one bug report on http://bugs.php.net/ could be related ? For instance, Bug #40503 : json_encode integer conversion is inconsistent with PHP ?

Maybe Bug #38680 could interest you too, btw ?

Answer 4

I'm encountering the same problem (PHP-5.2.11/Windows). I'm using this workaround

$json = preg_replace( "/\"(\d+)\"/", '$1', $json );

which replaces all (non-negative, integer) numbers enclosed in quotes with the number itself ('"42"' becomes '42').

See also this comment in PHP manual.

Answer 5

The following test confirms that changing the type to string causes json_encode() to return a numeric as a JSON string (i.e., surrounded by double quotes). Use settype(arr["var"], "integer") or settype($arr["var"], "float") to fix it.

<?php

class testclass {
    public $foo = 1;
    public $bar = 2;
    public $baz = "Hello, world";
}

$testarr = array( 'foo' => 1, 'bar' => 2, 'baz' => 'Hello, world');

$json_obj_txt = json_encode(new testclass());
$json_arr_txt = json_encode($testarr);

echo "<p>Object encoding:</p><pre>" . $json_obj_txt . "</pre>";
echo "<p>Array encoding:</p><pre>" . $json_arr_txt . "</pre>";

// Both above return ints as ints. Type the int to a string, though, and...
settype($testarr["foo"], "string");
$json_arr_cast_txt = json_encode($testarr);
echo "<p>Array encoding w/ cast:</p><pre>" . $json_arr_cast_txt . "</pre>";

?>