How to get closest date compared to an array of dates in PHP

Here Explain about how to find nearest date from any array of dates
Let's say I have an array as follows:

Array
(
    [0] => 2017-09-14
    [1] => 2017-09-15
    [2] => 2017-09-16
    [3] => 2017-09-17
    [4] => 2017-09-18
    [5] => 2017-09-19
)