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Web engineering: Lecture 21, 22 - Majid Mumtaz
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In this lecture, we will learn PHP Arrays. In PHP there are three type of arrays: Index arrays/Numeric, associative arrays, multidimensional arrays. In lecture 21 and 22, we will learn three type of PHP Arrays. Inviting you to refer.
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Nội dung Text: Web engineering: Lecture 21, 22 - Majid Mumtaz
- Web Engineering
Lecture 21-22
MAJID MUMTAZ
Department of Computer Science, CIIT Wah
1
- PHP Arrays
• What is an Array?
– An array stores multiple value in one signle variable.
Or we can say that
– ”An array is a special variable, which can hold more
than one same types of value”.
• In PHP there are three type of arrays
1. Index arrays/Numeric: Array with numeric index.
2. Associative arrays: Arrays with named keys
3. Multidimensional arrays: Arrays containing one or
more arrays
2
- PHP Arrays
• Index arrays/Numeric: A numeric array stores elements
with a numeric ID key. The numeric index can be assigned
automaticaly, and index will start at 0.
• Declaration:
$books = array(”php”, ”java”, ”c++”); OR
$books[0] = ”php”;
$books[1] = ”java”;
$books[2] = ”c++”;
Example:
3
- PHP Arrays
• The foreach loop statement: Is very handy to loop through arrays
• Syntax
foreach(array as value)
{
Code to be executed;
}
Example
4
- PHP Arrays
• Associative arrays: When storing data about specific
named values, a numeric array is not always the best way
to do it. The alternate solution is associative array. With
such arrays, each element is referenced by a string index.
Typically a numeric index is called an index and a string
index is called a key
• Associative arrays are arrays that use named keys that you
assign to them when storing data about specific named
values e.g.
$price = array(”php”=> ”532”, ”java”=> ”340”); OR
$price[’php’] = ”532”;
$price[’java’] = ”340”;
5
- PHP Arrays
• Using foreach statement in associative array
Example:
$price = array(”php”=> ”532”, ”java”=> ”340”);
Foreach ($price as $key=>$value)
{
echo $key. ”price is” . $value;
echo ””;
}
6
- PHP Arrays
• Multidimensional Arrays: In MD 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
• Example:
$shop = array(”laptop” => array(”Del”, ”Hp”,
”IBM”), ”printer” => array(”Hp”, ”Canon”));
echo $shop[’laptop’][2]; //IBM
7
- PHP Functions
• PHP Functions: Group of statement under single name
is called functions.
• A function is a block of code that can be executed
whenever we need it
– Why functions are useful
• To avoid duplicate code
• To make code easier to eliminate errors
• Type of functions
– User-defined functions: Functions which are created by
user or programmer is called user defined functions.
– Built-in functions: Built-in functions are also called ready-
made functions
• The real power of PHP comes from its functions
• In PHP there are more than 700 built-in functions available
8
- PHP Functions
• All function start with the word “function()”
• Name the function
• Add a ”{”, the function code starts after the opening curly brace
• Insert the function code
• Add a ”}”, the function is finished by a closing curly brace. At the
end you must call a function by using their name. E.g.
9
- PHP Functions
• Parameters Functions: A parameter is a variable that
holds the value passed to it when the function is called
• If we want to pass argument/parameter to the
function, we place them b/w the parentheses,
separating each argument by commas, i.e.
– functionName (argument)
– functionName(argument1, argument2, ...)
Example:
Function test($a){
echo ”The value is” . $a;
}
Test (12);
10
- PHP Functions
• PHP built-in functions: In PHP there are more than 700
built-in functions available
– Some of the built-in functions are
• Sqrt()
• Count()
• Sort() and so on
• Example:
11
- PHP Functions
• Sorting of Arrays: The element in an array can
be sorted in alphabetical or numeric order, i.e.
Ascending or Descending
A-Z Z-A
Small to large No. Large to Small No.
(1 to 10) (10 to 1)
12
- PHP Functions
• Sort Function for Arrays
Sort () Sorts an indexed array in ascending order
Rsort() Sorts an indexed array in descending order
Asort() Sorts an associative array in ascending order,
according to the value
Ksort() Sorts an associative array in ascending order,
according to the key
Arsort() Sorts an associative array in descending order,
according to the value
Krsort() Sorts an associative array in descending order,
according to the key
13
- Examples
• It will sort the element of the $books array in ascending alphabetical order
Sort the elements of the $numbers array in ascending numerical order
14
- Examples
There is a function available in PHP i.e count() that can be
used to give you total number of array elements.
15
- PHP Include() and require() functions
• Include() function takes all the test in a
specified file and copies it into the file that
uses the include function.
Syntax: include(”header.php”);
It is useful for modular programming. Another
function that is similar to include is the
require() function: syntax is
require (”head.php”);
16
- Difference between include() and
require() function
• The two functions are identical in every way,
except how they handle errors
– The include() function generates a warning ( but
the script will continue execution)
– Require() function generates a fatal error ( and the
script execution will stop after the error)
Note: Recommended function is require().
17
- PHP Date() function
• Date() function is used to format a time or a date. The
PHP date() function formats a timestamp to a more
readable date and time.
Syntax: date(format, timestamp);
The first parameter in the date() function specifies how to
format the date/time. It usese letters to represent date
and time format. Some of the letter that can be used:
– D – the day of the month (0 1– 31)
– M – the current month, as a number (01 – 12)
– Y – the current year in four digits.
– 1 - Represents the day of the week
Note: Other characters, like"/", ".", or "-" can also be
inserted between the characters to add additional
formatting. 18
- PHP Date() function
• What is a timestamp: Time stamp is the number
of second since January 1, 1970 at 00:00:00 GMT.
This is also known as the unix timestamp. Or
• A timestamp is an integer that holds the number
of seconds from january 1, 1970.
• The mktime() function returns the unix
timestamp for a specified date.
Syntax: mktime(hour, minute, second, month, day,
year)
19
- PHP forms & user input
• The php $_GET & $_POST variable are used to
retrieve information from forms, like user input.
• PHP $_GET: The $_GET variable is used to collect
values from a form with method=”GET”.
• The $_GET variable is used to collect values from
a form with a method=”GET”. Information sent
from a form with the GET method is visible to
everyone (It will be displayed in the browser’s
address bar) and it has limits on the amount of
information to send (max. 100 characters)
20
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