Php, in_array, 0 value

Question

I was trying to understand the `in_array` behavior at the next scenario: ``` $arr = array(2 => 'Bye', 52, 77, 3 => 'Hey'); var_dump(in_array(0, $arr)); ``` The returned value of the `in_array()` is boolean `true`. As you can see there is no value equal to `0`, so if can some one please help me understand why does the function return true?

Accepted Answer

This is a known issue, per the comments in the documentation. Consider the following examples:

```
in_array(0, array(42));      // FALSE
in_array(0, array('42'));    // FALSE
in_array(0, array('Foo'));   // TRUE
```

To avoid this, provide the third paramter, `true`, placing the comparison in strict mode which will not only compare values, but types as well:

```
var_dump(in_array(0, $arr, true));
```

Other work-arounds exist that don't necessitate every check being placed in strict-mode:

```
in_array($value, $my_array, empty($value) && $value !== '0');
```

But Why?

The reason behind all of this is likely string-to-number conversions. If we attempt to get a number from "Bye", we are given `0`, which is the value we're asking to look-up.

```
echo intval("Bye"); // 0
```

To confirm this, we can use `array_search` to find the key that is associated with the matching value:

```
$arr = array(2 => 'Bye', 52, 77, 3 => 'Hey');
echo array_search(0, $arr);
```

In this, the returned key is `2`, meaning `0` is being found in the conversion of `Bye` to an integer.

Php, in_array, 0 value

Solution

Problem