Question

I have array like

array(
    "v"=>1,
    "u"=>8,
    "v1"=>45,
    "v123"=>12
);

In my program i need to check whether the array contains an element whose key starts with v followed by numbers.My array is very large ,so that I do not prefer iteration.Is there any other efficient way to do this.I expect something like isset(arr[regex]);

Answer 1

You can use array_filter (http://php.net/manual/en/function.array-filter.php)

first creat a callback function:

function getKeys($n){
 return preg_match('/^v[0-9]+$/', $n);
}

Then run the array_filter:

$arr = array(
    "v"=>1,
    "u"=>8,
    "v1"=>45,
    "v123"=>12
);

$newArr = array_filter(array_keys($arr), "getKeys");

You can see the result with the right array_keys:

print_r($newArr);

If you have a result this statement should be true:

echo count($newArr) > 0;