Transcript PHP 5 Tutorial

Creating PHP Pages
Chapter 10
PHP Arrays
Arrays
• An array can store one or more values in a
single variable name.
• An element of an associative accessed by a
keyword so that it can be easily accessed.
• An associative array is like a dictionary or
map .
• An array element can be of any type.
• An array can be heterogeneous with its
element types and structure.
• Many functions manipulating an array are
provided.
Arrays
Array Types :
• Indexed and Associative Arrays, based on
whether the key is numeric or string.
• In a multidimensional array, each element in
the main array can also be an array.
• And each element in the sub-array can be an
array, and so on.
• PHP.net says: "There are no different indexed
and associative array types in PHP; there is only
one array type, which can both contain integer
and string indices.
Keyword
• An array key can be thought of as the
address or reference to a specific value
contained within an array.
• A key can be an integer or a string
Floats used as keys are truncated to
integers
• If you don't specify a key, the array key will
automatically start with 0 (zero) and auto
increment by 1 each time a new value is
entered into the array.
• Key must be unique.
Creating an Array
• An array can be created by the array()
language-construct. It takes a number
of comma-separated key => value pairs.
• Example
$person = array(‘manager'=>‘rico',
‘supervisor'=>‘john',
‘staff'=>‘mike')
Array Values
• Array values can be accessed a number
of ways. Most directly, arrays can be
output using print() and echo. However,
you have to indicate the key of the
value you wish to print, otherwise the
output will just be "Array".
Array Example
•
Create an array with numeric keys, automatically created
starting at zero:
$colors = array('red',
'green',
'blue')
echo $colors[1]; //green
echo $colors; //Array
echo $colors[0]; //red
•
Create an array with numeric with keys starting at 1, then
incremented automatically by 1:
$colors = array(1=>'red',
'green',
'blue')
echo $colors[1]; //red
echo $colors[3]; //blue
echo $colors[0]; //Notice: Undefined
Indexed Array
• Example :
$animals =
array("dog", "cat", "fish");
echo "$animals[0]\n";
echo "$animals[2]\n";
echo "$animals\n";
• Output :
dog
fish
Array
Associative Array
• Example :
$animals = array(
"dog“ => 15,"cat“ = >8, "fish“ => 2);
echo "$animals[cat]\n";
$animals["bat"] = 100;
echo "$animals[bat]\n";
• Output :
8
100
Listing Array
• Listing Array Elements: foreach
• Example :
$animals =
array("dog", "cat", "fish");
foreach ($animals as $animal)
echo "$animal\n";
}
• Output :
dog
cat
fish
Using while and each
• Example :
$animals = array(
"dog“ => 15,"cat“ => 8, "fish“ => 2);
while ($item = each($animals))
print "weight of " .
$item["key"] . " is " .
$item["value"] . “.\n";
• Output :
weight of dog is 15.
weight of cat is 8.
weight of fish is 2.
Using each and list
• Example :
$animals = array(
"dog“ => 15, "cat“ => 8, "fish“ => 2);
while (list($key, $value) =
each
($animals))
print "weight of $key is $value.\n";
• Output :
weight of dog is 15.
weight of cat is 8.
weight of fish is 2.
View Array Structure
• You can quickly view the keys and values of an
array using print_r() :
$colors = array('red',
'green',
'blue');
print "<pre>";
print_r($colors);
print "</pre>";
• Output :
Array
(
[0] => red
[1] => green
[2] => blue
)
View Array Structure
•
View the structure, keys and values of an array
using var_dump():
$colors = array('red',
'green',
'blue');
print "<pre>";
var_dump($colors);
print "</pre>";
•
Output :
array(3) {
[0]=>
string(3) "red"
[1]=>
string(5) "green"
[2]=>
string(4) "blue"
}
Delete Array Element
• After an array has been created, you can add
values to the 'end' of the array:
unset($colors[2]);
print "<pre>";
print_r($colors);
print "</pre>";
• Output :
Array
(
[0] => red
[1] => green
[3] => orange
)
Merge Array
• Combine arrays :
$colors = array('red',
'green',
'blue');
$others = array('purple',
'pink');
$all = array_merge($colors,$others);
• Output :
Array
([0] =>
[1] =>
[2] =>
[3] =>
[4] =>
)
red
green
blue
purple
pink
Count and Delete or Reset Array
• You can count the number of values in an
array :
$numColors = count ($colors);
• Delete an array :
unset($colors);
• Reset an array (delete all keys and values
but keep array) :
$colors = array();
Transform
•
Take the colors and transform them into a string with <br>
at the end of each color :
$newString = implode
('<br>',$colors);
•
Take the colors and transform them into a string with <br>
at the end of each color:
$names = "Bob, Terry, Carl";
$guysArray = explode(', ', $names);
print "<pre>";
print_r($guysArray);
print "</pre>";
Output :
Array
(
[0] => Bob
[1] => Terry
[2] => Carl
)
Sorting Arrays
•
•
•
•
Arrays can be sorted by key or value
You can sort and keep keys aligned, or sort values and
have new keys assigned.
Using sort () function, sort()is alphabetical if
values are strings, or numeric if values are numeric.
Example:
$colors = array('red',
'green',
'blue');
sort($colors);
print_r($colors);
Output :
Array
(
[0] => blue
[1] => green
[2] => red
)
Sorting Arrays
•
•
rsort() Function
rsort()sorts in reverse :
• Example:
$colors = array('green', 'red', 'blue');
rsort($colors);
print_r($colors);
Output :
Array
(
[0] => red
[1] => green
[2] => blue
)
Sorting Arrays
•
•
ksort() Function
ksort() keys, keeping values correlated to
keys :
• Example:
$colors = array('green', 'red', 'blue');
ksort($colors);
print_r($colors);
Output :
Array
(
[0] => green
[1] => red
[2] => blue
)
Multidimensional Arrays
• Arrays can contain other arrays.
• Example:
$fruits = array('apples',
'bananas',
'oranges');
$meats = array('steaks',
'hamburgers',
'hotdogs');
$groceries = array
('Fruit'=>$fruits, 'Meat'=>$meats);
Multidimensional Arrays
• Example:
Array
(
[Fruit] => Array
(
[0] => apples
[1] => bananas
[2] => oranges
)
[Meat] => Array
(
[0] => steaks
[1] => hamburgers
[2] => hotdogs
)
);
Array functions
•
•
•
•
•
•
•
•
•
count(), sizeof()
in_array()
array_slice()
array_pad()
array_reverse()
array_search()
list()
shuffle()
extract()
• Sorting Functions
•
•
•
sort(), rsort()
asort(), arsort()
ksort(), krsort()
References
References :
1.
2.
3.
4.
Anonymous.(n.d.). Apache HTTP Server Documentation
Version 2.2. Retrieved from
http://httpd.apache.org/docs/2.2/.
Achour, M., Betz, F. (n.d.), PHP Manual. Retrieved from
http://www.php.net/download-docs.php.
Anonymous. (n.d.). MySQL Reference Manual. Retrieved
from http://downloads.mysql.com/docs/.
Naramore, E., Gerner, J., Le Scouarnec, Y., Stolz, J., Glass, M.
K. (2005). Beginning PHP5, Apache, and MySQL® Web
Development. Indianapolis, IN: Wiley Publishing, Inc.