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PHP
PHP's name is an recursive acronym for: Hypertext Preprocessor
PHP script is an HTML- embedded scriting language Designed to do something only after event occurs. e.g. when user submit forms
A Server-Side language the code resides on a host computer that serves Web pages
to the requesting visitors (client). PHP is easy to use for Web development because it
has many built-in functions that make web programming simpler, so that programmers can focus on the logic of programming without wasting precious development time
PHP
client serverURL request
HTML
PHP
Script requestHTML
PHP Block
PHP code skeleton:
<?php …. ?>
<? … ?>
<script language = “PHP”> … </script>
First style
Second style
Third style
PHP Programming Style
Sending data to web browser
Use PHP built in functions Example
▪ echo ‘Hello Student’;▪ print “ How are you”;
Case-insensitive for function names▪ ECHO, echo, Echo
Other print functions print_r, var_dump - value of variable print_f - formatting what you print
White space, HTML and PHP
White spaces - blank lines, tabs and extra spaces To alter spacing of finished web page,
use▪ <br /> - line break ▪ <p></p> - paragraph
To alter spacing of HTML source from PHP, use▪ echo() or print() over the course of several
lines ▪ \n (newline character) within double
quotation marks
Writing comments
Important aspect to dynamic web site development
Viewable in the source but not in the browser window
PHP supports 3 type of comments # this is a comment // this is also a comment /* this is a larger comment that spans two line */
Variables
Rules of thumbVariable name must start with dollar
sign ($)Combination of strings, numbers and the
underscoreFirst character after dollar sign cannot
be a numberCase sensitiveAssigned value using equals sign (=)
String
A quoted chunk of letters, numbers, spaces, punctuation .. Example strings
‘hello’ ‘software’ ‘1000’ ’12 January, 2006’
String variable – assign a string value to valid variable name $today =’16 July, 2007’;
To print out echo $today; echo “Today is $today”;
Concatenation string Addition of strings using period (.).
▪ $day=‘12’;▪ $month=‘January’;▪ $year =‘2006’;▪ $today = $day . ’ ‘ . $month . ’ ‘ . $year;
Use it extensively when building database queries in later chapters
Numbers
Valid number-type variables can be 8 3.14 1098727272798 -4.2828282
Arithmetic operators + addition - subtraction * multiplication / division % modular ++ increment -- decrement
Numbers
Functions round()
▪ $j = 3.14;▪ $k = round( $j);
number_format()▪ $p =20980;▪ $g=number_format($p);▪ $g=number_format($p,2);
Constant
Specific data type Retain initial value throughout script Cannot change once it has been set
Use define()▪ define (‘AGE’, ‘value’);
Print constant▪ echo ‘Hello, ‘ . AGE; OR▪ echo ‘Hello,’, AGE;
Single vs Double Quotation Marks
Single quote -> values treated literally Double quote -> interpolated Example:
$var =‘Hello’;
echo “var equal to $var”;▪ var equal to hello
echo ‘var equal to $var’;▪ var equal to $var
echo “\$var is equal to $var”;▪ $var is equal to hello
Single vs Double quotation marks
“” replace variables name with its value
and a special character’s code (\$) with its represented value
‘’ display exactly what you type, except for
the escaped single quote (\’) and the escape backslash(\\).
PROGRAMMING WITH PHP
PROGRAMMING WITH PHP
Discuss on..
Creating an HTML form Handling an HTML form Conditional and Operators Validating Form Data Sending Values to A Script Manually What are Arrays For and While Loops
HTML form
Managing HTML form with PHP involves 2 steps :
1.Step 1:Create HTML form with any text editor• HTML form (.htm/.html) is created using the HTML
form tags and various input types.
2. Step 2:Create PHP scripts that receives form data• PHP script (.php) is created to receives the submitted
form data and handle it.
Handling HTML formStep 1: create html form
Step 2: create php scripts that receive form data
Step 1: create html form form.html
how dat ais sent(get or post)
which page the form data will be send
Step 2: create php script procesform.php
Superglobal variable
If you have a text box in html form with name attribute age, PHP will store the text entered there in a variable called $age (registered global variable)
$age is similar to $_POST[‘age’] (superglobal variables)
eg : ( in HTML form)
eg : ( in PHP scripts)
echo “<p>Thank you, {$_POST[‘age’]} for the following comments”;
<p><b>Age: </b><input type ="text" name=“age" size="20" maxlength="40"/></p>
attributes
Conditional and Operators Dynamic web frequently use conditionals to alter
script behavior 3 primary terms – if, else, elseif
Syntax:
if (condition) { // do something!}
if (condition) { // do something!} else { // do something else!}
if (condition1) { // do something!} elseif (condition2) { // do something else!} else { // do something else!}
Conditional and Operators Condition can be TRUE for any
number of reasons. Below are common TRUE conditions:
$var, if $var has a value other than 0, an empty string or NULL
isset($var), if $var has any value other than NULL, including 0 and an empty string.
TRUE
Conditional and Operators
Comparative and Logical Operators
Symbol Meaning Type example
= Is assigned the value of Assignment $n=1
== Is equal to Comparison $x==$y
!= Is not equal to Comparison $x!=$y
< Less than Comparison $x < $y
> Greater than Comparison $x > $y
Conditional and Operators switch
Used in place of a long if–elseif–else conditional
Syntax :switch ($variable) {
case ‘value1’ :// do thisbreak;
case ‘value2’ :// do thisbreak;
default :// do thisbreak;
}
Validating Form Data
Use of conditionals and any number of functions, operators and expressions. Common functions : empty(), strlen(), isset()
Aims of validating data
Why validate form?
• To ensure that something was entered or selected in form elements.
• To ensure that submitted data is of the right type (numeric, string, etc), of the right format (eg: email addr), or a specific acceptable value (eg: $gender is either M or F)
Sending Values to a script manually
2 ways to pass a PHP script variables and values
Use HTML hidden input type<input type=“hidden” name=”name” value=“Brian”/>- As long as this code is anywhere between the form
tags, the variable $name will have a value of ‘Brian’ in the handling PHP script
To append a value to the handling PHP scripts URLwww.smkbbb.edu.my/page.php?name=Brian- Emulate the get method of an HTML form
The $source variable
The page (handle_calculator.php) that handles the form (calculator.html) will receive a $source variable to indicate where the data (hidden input) came from.
The $source variable need also be validated; is set or not and if it is set with value, is the value correct or not.
Observe the action attribute in the form tag below :
appended!
What are Arrays?
An array can hold multiple, separate pieces of information List of values Each value being a string or a number or even
another array Structured as a series of key-value pairs.
Each item in the list, there is a key associate with it. Support 2 kind of arrays
Indexed – use numbers as the key Associative – use strings as key
What are Arrays?
Example – indexed $artists
Example – associative $states
Key Value
0 Low
1 Aimee
2 Ani Difranco
3 Spiritualized
Key Value
MD Maryland
PA Penssylvania
IL Illinois
MO Missouri
What are Arrays?
To retrieve a specific value from an array, refer to the array name, followed by the key, in square brackets echo $artists[2]; echo $states[‘MD’];
To print, wrap array name with curly braces echo “IL is the abbreviation for {$states[‘IL’]}.”;
Superglobal Arrays
Very useful and powerful tool By default, PHP uses several types of
arrays $_GET to store all of the variables and values sent via the get
method $_POST to store all of the variables and values sent via the
post method $_SESSION, $_COOKIE
Creating Arrays
Syntax to create arrays Add an element at a time
▪ $array[] =‘value’;▪ $array[] =‘value one’;▪ $array[‘key’] =‘more values’;
Use array() function to build an entire array▪ $array =array(‘key’ =>’value’, ‘key2’ => ‘value2’);▪ $array =array(‘value’,’value2’,’value3’);
Create an array of sequential numbers, use range()▪ $ten = range(1,10);
Accessing arrays
Access every array element, use foreach loop:Syntax :
foreach ($array as $value) echo $value ;
Iterate through every element in $array, assigning each element value to the $value variable.
To access both the keys and values Syntax : foreach ($array as $key => $value)
echo “The array value at $key is $value”;
Multidimensional arrays
An array consisting of other arrays Combine 2 arrays into 1 multidimensional array
▪ $states = array (‘MD’ =>’MaryLand’, ‘IL’ =>’Illinois’);▪ $provinces = array (‘QC’ =>’Quebec’, ‘AB’ =>’Alberta’);▪ $abbr = array (‘US’ =>$states, ‘Canade =>$provinces’);
To access $states array▪ $abbr[‘US’];
To access Maryland▪ $abbr[‘US’][‘MD’]
To print out▪ echo “The US state whose abbreviation is MD is {$abbr[‘US’][‘MD’]}.”;
Array and strings
2 functions for converting between strings and arrays $array = explode (separator, $string);
▪ Turning a string into an array▪ $string =‘Jan-Feb-Mac-Apr-May’;▪ $array =explode (‘-’, $string);
$string = implode (glue, $array);▪ Turning an array to string
▪ $string =implode (‘ , ’, $array);▪ $string= ‘Jan,Feb,Mac,Apr,May’;
Sorting Arrays
Use built in PHP function sort() – sort an array by value discarding the
original keys▪ The array keys will be reset after the sorting process
▪ Avoid use this function if key-value relationship is important.
asort() – sort an array by value while maintaining the key
ksort() – sort an array by key Each of these can sort reverse order by
changing them to ▪ rsort() , arsort() , krsort()
shuffle() – to randomize the order of an array
For and While Loops While loop
If the condition is still true, the loop will be executedSyntax :
while (condition) { // do something
} For loop first the initial expression is run, checked the condition
and if true, content of the loop is executed. After execution, checked closing expression with condition again.Syntax :
for (initial expression; condition; closing expression) { // do something
}