PHP get index of last inserted item in array

user_314056 0
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It's as easy as the title sounds; I need to get the index/key of the last inserted item. Why is this difficult? See the following two code samples:

$a=array();
echo 'res='.($a[]='aaa').' - '.(count($a)-1).'<br>';
echo 'res='.($a[]='bbb').' - '.(count($a)-1).'<br>';
echo 'res='.($a[]='aaa').' - '.(count($a)-1).'<br>';
die('<pre>'.print_r($a,true).'</pre>');

Writes:

res=aaa - 0
res=bbb - 1
res=aaa - 2
Array (
    [0] => aaa
    [1] => bbb
    [2] => aaa
)

Sure, that seems to work fine, but see this:

$a=array();
echo 'res='.($a[]='aaa').' - '.(count($a)-1).'<br>';
echo 'res='.($a[2]='bbb').' - '.(count($a)-1).'<br>';
echo 'res='.($a[]='aaa').' - '.(count($a)-1).'<br>';
die('<pre>'.print_r($a,true).'</pre>');

Writes:

res=aaa - 0
res=bbb - 1       <- wrong!
res=aaa - 2       <- wrong!
Array (
    [0] => aaa
    [2] => bbb    <- real key
    [3] => aaa    <- real key
)

So in short, the popular workaround count($array)-1 is flawed.

indexing arrays php
6 Answers

Here is a linear (fastest) solution:

end($a);
$last_id=key($a);
user_2048190
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