Getphp : PHP and MySQL resources

Booleans

This is the simplest type. A boolean expresses a truth value. It can be either TRUE or FALSE.

Note: The boolean type was introduced in PHP 4.

Syntax

To specify a boolean literal, use the keywords TRUE or FALSE. Both are case-insensitive.

<?php
$foo = True; // assign the value TRUE to $foo
?>
Typically, some kind of operator which returns a [...]

Variable functions

PHP supports the concept of variable functions. This means that if a variable name has parentheses appended to it, PHP will look for a function with the same name as whatever the variable evaluates to, and will attempt to execute it. Among other things, this can be used to implement callbacks, function tables, and [...]

Returning values

Values are returned by using the optional return statement. Any type may be returned, including arrays and objects. This causes the function to end its execution immediately and pass control back to the line from which it was called. See return() for more information.

Example #1 Use of return()

<?php
function square($num)
{
    return $num * $num;
}
echo square(4);   [...]

Function arguments

Information may be passed to functions via the argument list, which is a comma-delimited list of expressions.

PHP supports passing arguments by value (the default), passing by reference, and default argument values. Variable-length argument lists are also supported, see also the function references for func_num_args(), func_get_arg(), and func_get_args() for more information.

Example #1 Passing arrays to [...]

User-defined functions

A function may be defined using syntax such as the following:

Example #1 Pseudo code to demonstrate function uses

<?php
function foo($arg_1, $arg_2, /* …, */ $arg_n)
{
    echo “Example function.\n”;
    return $retval;
}
?>
Any valid PHP code may appear inside a function, even other functions and class definitions.

Function names follow the same rules as other labels in PHP. A [...]