Description:
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I tried to use the str_split() function as described in the current version of the PHP online manual when the following problem occured:

Fatal error: Call to undefined function: str_split() in test.php on line xx

Reproduce code:
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<?php
var_dump(str_split("abcdefgh"));
?>

Expected result:
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array(8) { [0]=> string(1) "a" [1]=> string(1) "b" [2]=> string(1) "c" [3]=> string(1) "d" [4]=> string(1) "e" [5]=> string(1) "f" [6]=> string(1) "g" [7]=> string(1) "h" }

Actual result:
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Fatal error: Call to undefined function: str_split() in test.php on line 2