问题
very simple. Consider this code:
var_export (11.2);
this returns with
11.199999999999999
with Php 5.6
wtf?
回答1:
From the comments on the man page of php.net:
Looks like since version 5.4.22 var_export uses the serialize_precision ini setting, rather than the precision one used for normal output of floating-point numbers. As a consequence since version 5.4.22 for example var_export(1.1) will output 1.1000000000000001 (17 is default precision value) and not 1.1 as before.
Good to know. I too was not aware of this change.
serialize_precision
Available since PHP 4.3.2. Until PHP 5.3.5, the default value was 100.
So, we can get the behavior we were familiar with using: ini_set('serialize_precision', 100);
Warning
Be very careful when using ini_set(), as this may change behaviour of your code further down the line. A "safe" way would be to use something like this:
$storedValue = ini_get('serialize_precision');
ini_set('serialize_precision', 100);
// Your isolated code goes here e.g var_export($float);
ini_set('serialize_precision', $storedValue);
This ensures that changes further down/deeper in your code is not affected.
Generally, using ini_set() in your code should be considered dangerous, as it can have severe side effects. Refactoring your code to function without the ini_set() is usually a better choice.
来源：https://stackoverflow.com/questions/32149340/php-var-export-fails-with-float