This is my first php program!

Data Types
|
27
• The empty string (
""
) and the string
"0"
• An array with zero elements
• An object with no values or functions
• The
NULL
value
Any value that is not false is true, including all resource values (which are described
later, in the “Resources” section).
PHP provides
true
and
false
keywords for clarity:
$x = 5; // $x has a true value
$x = true; // clearer way to write it
$y = ""; // $y has a false value
$y = false; // clearer way to write it
Use the
is_bool( )
function to test whether a value is a boolean:
if (is_bool($x)) {
// $x is a boolean
}
Arrays
An array holds a group of values, which you can identify by position (a number, with
zero being the first position) or some identifying name (a string):
$person[0] = "Edison";
$person[1] = "Wankel";
$person[2] = "Crapper";
$creator['Light bulb'] = "Edison";
$creator['Rotary Engine'] = "Wankel";
$creator['Toilet'] = "Crapper";
The
array( )
construct creates an array:
$person = array('Edison', 'Wankel', 'Crapper');
$creator = array('Light bulb' => 'Edison',
'Rotary Engine' => 'Wankel',
'Toilet' => 'Crapper');
There are several ways to loop across arrays, but the most common is a
foreach
loop:
foreach ($person as $name) {
echo "Hello, $name\n";
}
foreach ($creator as $invention => $inventor) {
echo "$inventor created the $invention\n";
}
Hello, Edison
Hello, Wankel
Hello, Crapper
Edison created the Light bulb
Wankel created the Rotary Engine
Crapper created the Toilet
,ch02.15294 Page 27 Wednesday, March 13, 2002 11:42 AM

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