PHP array has only one entry,how to get its key?

Question

$arr['thisiskey'] = 1；

Like above,how to get "thisiskey" programmatically?

Answer 1

Use array_keys:

$keys = array_keys($array);
var_dump($keys[0]);

Answer 2

foreach ($arr as $key => $value) { echo $key . PHP_EOL; }

Answer 3

list($key, ) = each($arr);
print $key;

Answer 4

Iteratively:

foreach ($array as $key => $value){

    print $key . ' = ' . $value .'\n';

}

Answer 5

The simplest solution:

key($arr);

key returns current key of the array