PHP: Use floats with given precision in json_encode() function

Asked Jul 10 '17 at 13:17

Active Jul 10 '17 at 14:40

Viewed 38 times

I need to use PHP floats in JSON string. Code:

$obj['val'] = '6.40';
json_encode($obj);

is converted to:

{"val": "6.40"}

It's OK - I have string value '6.40' in PHP and I have string value "6.40" in JSON.

The situation is not so good if I need to use floats:

$obj['val'] = 6.40;
json_encode($obj);

is converted to:

{"val": 6.4000000000000004}

but I need:

{"val": 6.40}

How can I convert PHP floats to JSON number in 'json_encode' with given precision?

edited Jul 10 '17 at 14:40

asked Jul 10 '17 at 13:17

Alex Gusev

GOOGLE `what every programmer needs to know about floating point` – RiggsFolly Jul 10 '17 at 13:19
the question is not "how to round floats in PHP?" the question is "how to round floats in 'json_encode' function?" – Alex Gusev Jul 10 '17 at 14:38
Floats are never 100% accurate; you cannot depend on a float have any one specific accurate value. You must live with imprecisions when using floats. – deceze Jul 10 '17 at 14:50
python converts own floats to JSON numbers with given precision: `round(tools.float_round(6.40, precision_digits=2), 2)` – Alex Gusev Jul 10 '17 at 15:24
yes, PHP floats are not 100% accurate but what about JSON numbers? https://www.w3schools.com/js/js_json_datatypes.asp – Alex Gusev Jul 10 '17 at 15:26
1

there is `ini_set('serialize_precision', ...)` option in PHP that affects to the output of `json_encode()` – Alex Gusev Jul 14 '17 at 15:18
`ini_set('precision', ...)` is the right answer. – Alex Gusev Jul 14 '17 at 15:27

0 Answers0