Bug #50224 [Nab->ReO]: json_encode() does not always encode a float as a float

Edit report at https://bugs.php.net/bug.php?id=50224&edit=1 ID: 50224 Updated by: tyrael@php.net Reported by: christian dot lawrence at calorieking dot com Summary: json_encode() does not always encode a float as a float -Status: Not a bug +Status: Re-Opened Type: Bug Package: JSON related PHP Version: 5.2SVN-2009-11-19 (snap) Block user comment: N Private report: N Previous Comments: ------------------------------------------------------------------------ [2014-07-15 11:44:55] tyrael@php.net I think it would be nice looking into how others handle this issue. Here is a comparision for the various json modules for python: http://deron.meranda.us/python/comparing_json_modules/numbers "Python floating point numbers (float) should be representable as JSON. JSON represents numbers with decimal fractions, and optional base-10 exponents. A floating-point number with a zero a fractional part, such as 1.0, could reasonably be converted to the JSON number 1 as well as 1.0; however no implementations choose to drop the fractional part." the json ruby gem also seems to keep the fraction: #!/usr/bin/ruby require 'json' require 'pp' pp JSON.parse(JSON.generate([1.0])) outputs [1.0] I would be curious if there are other widely used json encoder implementations which are dropping the fraction for the integer numbers. I think that keeping the fraction all times for floats wouldn't hurt anybody, but it could be useful for some people, and from my quick test this seems to be the common behavior, so I think we should follow it too. ------------------------------------------------------------------------ [2014-03-29 23:52:26] jrbasso at gmail dot com The problem is still present in version 5.5.10. I opened a PR to resolve it. https://github.com/php/php-src/pull/635 ------------------------------------------------------------------------ [2013-07-03 13:42:20] chr dot tatu at gmail dot com The problem is still present in version 5.4.6. var_dump says this values is float, but after applying json_encode and json_decode the value gets to be an int. For the jsoncpp library there is a difference between int and float and that difference is acknowledged by the floating point. ------------------------------------------------------------------------ [2012-07-13 23:09:50] josh dot adell at gmail dot com This is still an issue, specifically when JSON encoding for talking to APIs that don't allow mixed type arrays. For instance, json_encode(array(1.2, 2.3)) properly encodes to "[1.2, 2.3]" But, json_encode(array(1.0, 2.3)) encodes to "[1, 2.3]" which fails if the receiving end does not allow mixed-type arrays. Any chance on this ever being fixed? PHP Version: 5.3.10 ------------------------------------------------------------------------ [2009-11-20 10:39:53] christian dot lawrence at calorieking dot com And there lines the problem - there is no way to express the fractional part if json_encode() does not even deal with it in the first place. An integer and an integer represented as a floating point number are not the same thing because they have different types, as follows: <?php $a = 12; var_dump($a); //int(12) $b = 12.0; // This has a fractional part, hence it is a floating point number and not an integer var_dump($b); //float(12) var_dump($a === $b); //bool(false) ?> Numerically they have the same value, but we all know this to be true: <?php var_dump($a == $b); //bool(true) ?> There is always a fractional part of any integer when it is represented as a floating point number. It is implied and can, simply, be expressed by appending a ".0" to the integer part. There is nothing in the JSON encoding rules on http://www.json.org/ which disallows this (see "int frac" form for specifics). Decoding a valid and legitimate encoding of an integer when it is represented as a floating point number gives the correct PHP floating point type: <?php var_dump(json_decode("12.0")); //float(12) ?> Decoding an integer-encoded stream also gives the correct PHP integer type: <?php var_dump(json_decode("12")); //int(12) ?> I fail to see how my bug report is bogus when json_encode() is unable to produce a perfectly valid and legitimate encoding yet json_decode() is capable of doing the right thing. Surely, the json_encode() implementation must be identifying the data type being encoded, presumably it is using equivalents for is_object() and is_array(). Why not use equivalents for is_int() or is_float() as well? A reliable data interchange format should not purport to do any type-casting from the primitive types it was provided for encoding. ie: If you encode a float then you should expect to decode a float. As far as I am concerned json_encode() is un-reliable and fails to encode my float, which I have confirmed in my results. I humbly ask that you reconsider your position. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=50224 -- Edit this bug report at https://bugs.php.net/bug.php?id=50224&edit=1