[PHP]: What does array_search() return if nothing was found?

What does array_search() return if nothing was found?

I have the need for the following logic:

$found = array_search($needle, $haystack);

if($开发者_如何学运维found){
  //do stuff
} else {
  //do different stuff
}

Quoting the manual page of array_search() :

Returns the key for needle if it is found in the array, FALSE otherwise.

Which means you have to use something like :

$found = array_search($needle, $haystack);

if ($found !== false) {
    // do stuff
    // when found
} else {
    // do different stuff
    // when not found
}

Note I used the !== operator, that does a type-sensitive comparison ; see Comparison Operators, Type Juggling, and Converting to boolean for more details about that ;-)

if you're just checking if the value exists, in_array is the way to go.

One has to be very careful to distinguish the cases item found with index 0 and not found.

In the first case array_search returns the integer 0, in the second it returns the bool false.

⚠ Danger zone here because if we don't pay attention, it's easy to have 0 and false considered as the same thing in a if test. ⚠

If you want to be able to distinguish both, you have to use if ($i !== false), and not if ($i) or if ($i != false). Why? See the following example:

Example:

$array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red');

$i = array_search('red', $array);   
var_dump($i);                      // int(1)
echo ($i !== false) ? $i : -1;     // 1

$i = array_search('blue', $array); 
var_dump($i);                      // int(0)
echo ($i !== false) ? $i : -1;     // 0      // CORRECT
echo ($i != false) ? $i : -1;      // -1     // WRONG! don't use:  if ($i) ...
echo ($i) ? $i : -1;               // -1     // WRONG! don't use:  if ($i != false) ...

$i = array_search('blueee', $array);
var_dump($i);                      // bool(false)
echo ($i !== false) ? $i : -1;     // -1, i.e. not found

According to the official documentation at http://php.net/manual/en/function.array-search.php:

Warning This function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE. Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.

See this example:

$foundKey = array_search(12345, $myArray);
if(!isset($foundKey)){
    // If $myArray is null, then $foundKey will be null too.
    // Do something when both $myArray and $foundKey are null.
} elseif ($foundKey===false) {
    // $myArray is not null, but 12345 was not found in the $myArray array.
}else{
    // 12345 was found in the $myArray array.
}

From the docs:

Searches haystack for needle and returns the key if it is found in the array, FALSE otherwise.

array_search will return FALSE if nothing is found. If it DOES find the needle it will return the array key for the needle.

More info at: http://php.net/manual/en/function.array-search.php