Empty variable define in php

Question

Before doing something with $error:

$error = NULL;

In some script's saw:

$error = '';
$error = false;
$error = 0;

• Which method is 'better' or maybe it depends in which situation i use it ?
• What's your suggestion ?

Answer 1

Depends on your design:

• Are you setting it as an Object in case of error? Use NULL.
• Are you setting it to true in case of error? Use false.
• Are you setting it as a number of some sort in case of error? Use 0.
• Are you setting it to a string to describe the error? Use ''.

A better way to indicate errors would be throwing Exceptions though, rather than setting a variable and determine the error according to it.

Answer 2

There is no canonical answer to this question. As long as you use one of these semaphores consistently, you can use anything you want. Because PHP is loosely-typed, all of these values are "falsy" and can be evaluated in a boolean comparison as FALSE.

That said, there is more of a difference between the empty string and the others, so I'd stick with NULLs and FALSEs in this sort of scenario.

Answer 3

1.

$v = NULL;

settype($v, 'string');
settype($v, 'int');
settype($v, 'float');
settype($v, 'bool');
settype($v, 'array');

var_dump($v);

2.

$v = NULL;
var_dump( (string) $v);
var_dump( (int) $v);
var_dump( (float) $v);
var_dump( (bool) $v);
var_dump( (array) $v);

Answer 4

It depends upon the conditions where you need to use the $error. Using a NULL is what I chose mostly as I deal more with MySQL clauses and all!