'true' in Get variables

Question

In PHP, when you have something in the URL like "var=true" in the URL, does the 'true' and 'false' in the URL get translated to boolean variables, or do they equal the text 'true' or 'false'? For instance, would, with the url having "var=false" in it:

if ($_GET['var'] == false) { ... }

work? Or would the variable always be true since it has text in it?

Answer 1

They are passed as strings, so are always truthy unless they are one of these, which evaluate to false instead:

• The empty string ''
• A string containing the digit zero '0'

To make my life easier I just pass boolean GET variables as 1 or 0 and validate them to be either one of those values, or decide on a default value appropriately:

// Default value of false
$var = false;

if (isset($_GET['var']))
{
    if ($_GET['var'] === '1' || $_GET['var'] === '0')
    {
        $var = (bool) $_GET['var'];
    }
}

Answer 2

No, $_GET will always contain only strings.

However, you can filter it to get a boolean.

FILTER_VALIDATE_BOOLEAN:
Returns TRUE for "1", "true", "on" and "yes". Returns FALSE otherwise. If FILTER_NULL_ON_FAILURE is set, FALSE is returned only for "0", "false", "off", "no", and "", and NULL is returned for all non-boolean values.

Example:

$value = filter_input(INPUT_GET, "varname", FILTER_VALIDATE_BOOLEAN,
    array("flags" => FILTER_NULL_ON_FAILURE));