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up vote 0 down vote favorite

What is a simple method to return the array key when using array[] to add new values.

For example:

$array[] = 'Hello World';
return $Key_of_Hello_World;

The method I'm thinking of involves:

$key = count($array)-1;

Is there a different solution?

Conclusion

A combination of end() and key() is the best in general as it allows for associative but if your array only uses numerical keys, count()-1 seems to be the simplest and just as fast. I added this to the other linked question.

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uk.php.net/manual/de/function.array-flip.php –  Rufinus Mar 10 at 5:15
1  
end($array); $key = key($array); –  Sean Mar 10 at 5:16
1  
possible duplicate of PHP get index of last inserted item in array –  Patrick Evans Mar 10 at 5:16
    
Thanks Patrick. I must have just not searched hard enough. –  Devon Mar 10 at 5:27
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4 Answers

up vote 2 down vote accepted 
$array[] = 'Hello World';
end($array); // set internal pointer to end of array
$key = key($array); // get key of element where internal pointer is pointing at
return $key;
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This appears to be the fastest solution, although requiring two lines of code. Another solution suggested in the other thread was $key = end(array_keys($array)); which is a tiny bit slower but only requires one line. I'm still pondering whether count-1 will work well enough though as it seems just as fast as this method but obviously wouldn't work with associative like this would. –  Devon Mar 10 at 5:31
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up vote 1 down vote

You can do something like this too..

<?php

function printCurrKey(&$array)
{
    return array_keys($array)[count($array)-1];
}

$array[] = 'Hello World';
echo printCurrKey($array);// "prints" 0
$array[] = 'This is a new dimension !';
echo printCurrKey($array);// "prints" 1
$array['newkey'] = 'Hello World is has a new key !';
echo printCurrKey($array);// "prints" newkey
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1  
Yes for using the [] it seems count-1 may be the best method. Only requires one line and is extremely fast. array_search can be a bit slower with larger arrays but it is a interesting method. +1 –  Devon Mar 10 at 5:33
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up vote 0 down vote

you want to use array_keys: http://us1.php.net/manual/es/function.array-keys.php

$array[] = 'Hello World';
return array_keys($array, 'Hello World!');
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up vote 0 down vote

you can use array_keys() for return keys of an array

return array_keys($array)

for individual key try to use

return array_keys($array, 'Hello World!');
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