Using Optional Parameters : Parameters « Functions « PHP

Using Optional Parameters

$access = array('a', 'c', 'h', 'r', 'r');
$admin = array('e', 'q');

function check_access($username, $adminonly = false) {
    global $access, $admin;

    if (in_array($username, $admin)) {
        return true;

    if (!($adminonly) && in_array($username, $access)) {
        return true;

    return false;

echo check_access('r') ? 'is' : 'is NOT' ," allowed.</p>";
echo check_access('q') ? 'is' : 'is NOT' ," allowed.</p>";

echo check_access('r', true) ? 'is' : 'is NOT' ," an admin.</p>";
echo check_access('q', true) ? 'is' : 'is NOT' ," an admin.</p>";

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1.Functions and References
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3.Declaring a Function with Arguments
4.Function with default parameters
5.Passing Variables as a Reference to the Argument of a Function
6.Passing an Argument to a Function by Value
7.Using a Function Call to Pass an Argument to a Function by Reference
8.Declaring a Function That Requires Arguments
9.Function with an Optional Argument
10.A Function with an Optional Argument
11.Accessing Function Parameters
12.All optional arguments
13.Capturing a return value
14.Changing argument values
15.Defining and Calling a two-argument function,
16.Function Arguments
17.Function with two parameters
18.Creating Functions That Take a Variable Number of Arguments
19.Creating a capitalize function with a default parameter $each
20.Default Parameters
21.Define whether a variable is passed by value or reference
22.Passing By Reference
23.Making arguments be passed by reference