What common mistake did the user make in using the in_array() function in their code?

The common mistake the user made in using the in_array() function is that they did not set the third parameter to true, which specifies strict comparison. This means that the function will check both the value and the type of the elements in the array. By default, the function performs loose comparison, which can lead to unexpected results. To fix this issue, the user should set the third parameter of in_array() to true to ensure strict comparison. This will prevent any type coercion and ensure that both the value and the type of the elements are checked.

// Incorrect usage
$array = [1, 2, '3'];
if (in_array(3, $array)) {
    echo 'Value found in array';
} else {
    echo 'Value not found in array';
}

// Corrected usage
$array = [1, 2, '3'];
if (in_array(3, $array, true)) {
    echo 'Value found in array';
} else {
    echo 'Value not found in array';
}