This content originally appeared on DEV Community and was authored by Thien DX
Fast, flexible and pragmatic, PHP powers everything from your blog to the most popular websites in the world. Still during my work, I found it can have tricky behaviors that you may not aware of (yet) and create bugs in your code.
Here are some of the most common mistakes I encountered :
array_merge
Syntax : array_merge ( array ...$arrays ) : array
The function simply merges the elements of arrays together. But it also reset the keys of elements if it's numeric.
For example, a very basic use-case where you have arrays storing [UserId => UserName] :
$userArr1 = [1 => "John", "3" => "Mary"];
$userArr2 = [6 => "Ted", "22" => "Doe"];
$allUser = array_merge($userArr1, $userArr2);
// $allUser will be
// Array
// (
// [0] => John
// [1] => Mary
// [2] => Ted
// [3] => Doe
// )
Casting the numeric value to string like (string)10 won't work. This behavior is same for array_merge_recursive(), so you should keep this in mind when calling these functions.
empty
Syntax : empty ( mixed $var ) : bool
This check whether a variable is empty. Many use this function to check whether a key is set in array. It's all good and simple until value 0 came in.
For example, an user submit formed validation code :
// Function to check all required field are provided by user
function checkRequiredFields ($input) {
$requiredField = ['name', 'age', 'number_of_kids'];
$errors = '';
foreach ($requiredField as $field) {
if (empty($input[$field])) {
$errors.= "$field is missing";
}
}
return $errors;
}
// A valid use-case in real likfe
$userData = ['name' => 'John', 'age' => 22, 'number_of_kids' => 0];
$inputError = checkRequiredFields($userData);
// This return "number_of_kids is missing"
This is because 0 is also considered as "empty" even though it's a valid response in many use-cases. I find people make this mistake mostly when validating user's input.
A work around is adding strlen($var)
!isset($input[$field]) || strlen($input[$field]) == 0
Ternary operator (?:) vs null coalescing operator (??)
When your first argument is null, they're basically the same
$a = null;
print $a ?? 'default'; // default
print $a ?: 'default'; // default
$b = ['a' => null];
print $b['a'] ?? 'default'; // default
print $b['a'] ?: 'default'; // default
Except that the Ternary operator will output an E_NOTICE when you have an undefined variable.
But when the first argument is not null, they are different :
$a = false ?? 'default'; // false
$b = false ?: 'default'; // default
That's it.
Hope my short article can save you some debugging time.
This content originally appeared on DEV Community and was authored by Thien DX
Thien DX | Sciencx (2021-04-30T10:20:01+00:00) Some mistakes you may make in PHP. Retrieved from https://www.scien.cx/2021/04/30/some-mistakes-you-may-make-in-php/
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