PHP if (variable)

Question

In various PHP tutorials I see this syntax -

if ($_POST) {
  do something
}

I want to know whether this is equivalent to either isset or !(empty) (either one) or has different properties.

Answer 1

It attempts to evaluate the expression and cast it to boolean.

See 'Converting to boolean' at http://php.net/manual/en/language.types.boolean.php to see which values will be equivalent to true and which to false.

It does NOT however check for array key existence (i.e. isset), so if you try if ($_GET['somekey']) but somekey does not exist, you will see PHP Notice: Undefined index: somekey and then false will be assumed.

The best practice would be to perform empty() or isset() checks manually first as fits.