Best way to check if a variable exists?

[bunner_bob]

In the interests of proper coding, I was wondering what's the best syntax for checking whether a variable exists/is set?

if ($variable) {
[do something]
}

if (isset($variable)) {
[do something]
}

if ($variable != null) {
[do something]
}

if ($variable != "")
[do something]
}

This applies both to variables set within a script and values returned from a database (e.g. "if ($myrow['variable'])")

Thanks!

• Bob

[ultraslacker]

From the manual:

$var = 0;

if (empty($var)) {  // evaluates true
    echo '$var is either 0 or not set at all';
}

if (!isset($var)) { // evaluates false
    echo '$var is not set at all';
}