Description:
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As seen on the example code below, conversion to full year from short year is done in the range 1970 -> 2069.  However, this is not specified in the documentation.

The reason this isn't "obvious" is because some languages allow you to specify the range of conversion, and others seem to use a different range.
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From manual page: https://php.net/function.date
---


Test script:
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<?php
for ($x = 10; $x <= 99; $x++) {
	$dateString = "1/1/$x";
	echo "$dateString: " . DateTime::createFromFormat("m/d/y", $dateString)->format("Y") . "<br>";
}
?>