Precautions and example analysis of modifying array key with array_unshift() in php

This article mainly introduces the precautions for modifying the array key with array_unshift() in PHP. The example analyzes the situation where the array_unshift() function automatically converts the key value when the key value is a numeric type. Friends who need it can refer to it

As we all know, array_unshift() is used to add elements to the beginning of the array, but today I suddenly discovered thatIf the key value of the array is of numeric type (or can be converted to numeric type), array_unshift() will modify all The Keyof an element whose key is a number is really a trap

Example:

$a=array(111=>"dddddddddddd","112"=>array("one"=>"orange","two"=>"hhhhh"), "113"=>array("one"=>"orange","two"=>"hhhhh"),"oooo"=>"jjjjj"); print_r($a);echo "
"; array_unshift($a, "aaaaaaaaa"); print_r($a);echo "
";

Output result:

Array ( [111] => dddddddddddd [112] => Array ( [one] => orange [two] => hhhhh ) [113] => Array ( [one] => orange [two] => hhhhh ) [oooo] => jjjjj ) Array ( [0] => aaaaaaaaa [1] => dddddddddddd [2] => Array ( [one] => orange [two] => hhhhh ) [3] => Array ( [one] => orange [two] => hhhhh ) [oooo] => jjjjj )

See it, the array key value changed after array_unshift(), the original 111 became 1, what a trap! Everyone needs to pay special attention to this when using array_unshift() in the future!

Summary: The above is the entire content of this article, I hope it will be helpful to everyone's study.

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