---
array (
0 => 10,
1 => 20,
2 => 30,
3 => 1,
)
---
1
Warning: Decrement on type null has no effect, this will change in the next major version of PHP in /in/CjFPn on line 8
array (
0 => 10,
1 => 20,
2 => 30,
3 => 1,
4 => 1,
5 => NULL,
)
===
Warning: Decrement on type null has no effect, this will change in the next major version of PHP in /in/CjFPn on line 11
NULL