Week 4- Intro to PHP

8/21/2019 Week 4- Intro to PHP

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Important!

Please use the following site to test yourPhp codes (as of this moment).

http://codepad.org/

->and select Php -> write the codes on the text area

provided , the click submit
http://codepad.org/http://codepad.org/


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Learning PHP


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Drawbacks of HTML

HTML only allows for creating static webpages, or web pages that do not change

It does not, by itself, provide a way for

users to interact


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Learning PHP

PHP is a powerful server-side scripting languagefor creating dynamic and interactive websites.

PHP is the widely-used and free.

PHP is perfectly suited for Web developmentand can be embedded directly into the HTMLcode.

The PHP syntax is very similar to C.

PHP is often used together with Apache (webserver) on various operating systems.


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Introduction to PHP

A PHP file may contain text, HTML tagsand scripts.

Scripts in a PHP file are executed on the

server.


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How PHP Works

When a user navigates in her browser to a page that ends with a .php extension, the request is sent to a webserver, which directs the request to the PHP interpreter.

As shown in the diagram above, the PHP interpreter processes the page, communicating with file systems,databases, and email servers as necessary, and then delivers a web page to the web server to return to thebrowser.


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What You Should Already Know

Before you continue you should have abasic understanding of the following:

HTML / XHTML

Some scripting knowledge


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What is PHP?

PHP standsfor PHP: Hypertext Preprocessor

PHP is a server-side scripting language

PHP scripts are executed on the server PHP supports many databases (MySQL,

etc.)

PHP is an open source software PHP is free to download and use


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What is a PHP File?

PHP files may contain text, HTML tagsand scripts

PHP files are returned to the browser as

plain HTML PHP files have a file extension of ".php",

".php3", or ".phtml"


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Why PHP?

PHP runs on different platforms (Windows,Linux, Unix, etc.)

PHP is compatible with almost all servers

used today (Apache, etc.) PHP is FREE to download from the official

PHP resource:www.php.net

PHP is easy to learn and runs efficientlyon the server side
http://www.php.net/http://www.php.net/http://www.php.net/


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Where to Start?

Install an Apacheserver on a Windows orLinux machine

Install PHPon a Windows or Linux

machine Install MySQLon a Windows or Linux

machine

Or

you can install XAMMP


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Setup and installation of XAMPP

Download XAMPP for your operatingsystem from:

www.apachefriends.org/en/xampp.html

If you are using Windows, just run theinstaller (disable proxies)

If you are using Linux, untar the package

to the appropriate directory and run:/opt/lampp/lampp start


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How do you make a PHP program?

The process is identical to how you make anHTML page, even if you use a visual tool likeDreamweaver

Create an HTML page in any editor (even

notepad will work)

Add PHP code to the page

Save in your webserver directory

opt\lampp\htdocsin Linux C:\Program Files\xampp\htdocsin Windows

View in any web browser


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PHP Syntax


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PHP Syntax

You cannot view the PHP source code byselecting "View source" in the browser -you will only see the output from the PHP

file, which is plain HTML. This is because the scripts are executed

on the server before the result is sent back

to the browser.


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Basic PHP Syntax

A PHP scripting block always startswith . A PHP scriptingblock can be placed anywhere in the document.


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Basic PHP Syntax

A PHP file normally contains HTML

tags, just like an HTML file, and somePHP scripting code.

We have an example of a simple PHPscript which sends the text "HelloWorld" to the browser.

Each code line in PHP must end with asemicolon.

The semicolon is a separator and isused to distinguish one set ofinstructions from another.

There are two basic statements tooutput text with PHP: echoand print.

In the example above we have usedthe echo statement to output the text"Hello World".


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Comments in PHP

In PHP, we use // tomake a single-linecomment or /* and */to make a large

comment block.


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Hands-on 1: Hel lo world Please open a text editor, Notepad if you are in windows

Type the follow into the text editor:

Me and PHP

Save the file as handson1.php(add quotes if you areusing Windows)

Open a web browser

Type http://localhost/handson1.php and hit


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Expected Output:


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PHP Variables

Variables are used for storing values,such as numbers, strings or function

results, so that they can be used manytimes in a script.


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Variables in PHP

All variables in PHPstart with a $ signsymbol. Variablesmay contain strings,

numbers, or arrays. In the example, the

PHP script assignsthe string "HelloWorld" to a variablecalled $txt.


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Variables in PHP

To concatenate twoor more variablestogether, use the dot(.) operator.

The output of thescript will be: "HelloWorld 1234".


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Variable Naming Rules

A variable name must start with a $ sign symboland then followed by a letter or an underscore"_"

A variable name can only contain alpha-numeric

characters and underscores (a-Z, 0-9, and _ )

A variable name should not contain spaces.

If a variable name should be more than one

word, it should be separated with underscore($my_string), or with capitalization ($myString)

H d 2


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Hands -on 2:

Exper iment ing w ith var iables

Create a PHP program with variable namedtest (remember the dollar sign). Then do thefollowing:

a. store the number 35 to test and print the

result;

b. add 10.0000 to test and print the result;

c. subtract 5.123123 from test and print it out;

d. store the character string happy to behere to test and print;

e. add 10.0000 to the variable test and print.

Save it as handson2.php, and demonstrate it.


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PHP Operators

Operators are used to operate onvalues.

This section lists the different operatorsused in PHP.

SameWith

C


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Arithmetic OperatorsOperator Description Example Result

+ Addition x=2x+2

4

- Subtraction x=2

5-x

3

* Multiplication x=4

x*5

20

/ Division 15/5

5/2

3

2.5

% Modulus (division

remainder)

5%2

10%8

10%2

1

2

0++ Increment x=5

x++

x=6

-- Decrement x=5

x--

x=4

SameWith

C


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Assignment Operators

Operator Example Is The Same As

= x=y x=y

+= x+=y x=x+y

-= x-=y x=x-y

*= x*=y x=x*y

/= x/=y x=x/y

%= x%=y x=x%y

SameWith

C


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Comparison Operators

Operator Description Example

== is equal to 5==8 returns

false

!= is not equal 5!=8 returns

true

> is greater than 5>8 returns

false

< is less than 5= is greater thanor equal to

5>=8 returnsfalse


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Logical Operators

Operator Description Example

&& and x=6

y=3

(x < 10 && y >

1) returns

true|| or x=6

y=3

(x==5 || y==5)

returns false

! not x=6

y=3

!(x==y) returns

true

SameWith

C


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Conditional Statements

Very often when you write code, you want toperform different actions for different decisions.

You can use conditional statements in your codeto do this.

if...else statement- use this statement if youwant to execute a set of code when a conditionis true and another if the condition is not true

elseif statement- is used with the if...elsestatement to execute a set of code if oneofseveral condition are true

SameWith

C


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The If...Else Statement

Example

The following examplewill output "Have a niceweekend!" if the currentday is Friday, otherwise it

will output "Have a niceday!":

SameWith

C


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The If...Else Statement

If more than one line should beexecuted if a condition istrue/false, the lines should beenclosed within curly braces:

SameWith

C


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The ElseIf Statement

Example

The following example willoutput "Have a nice weekend!"if the current day is Friday, and"Have a nice Sunday!" if thecurrent day is Sunday.

Otherwise it will output "Have anice day!":


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PHP Switch Statement

Example

This is how it works: A single expression (most

often a variable) is evaluatedonce

The value of the expression iscompared with the values foreach case in the structure

If there is a match, the codeassociated with that case isexecuted

After a code isexecuted, break is used to stop

the code from running into thenext case

The default statement is usedif none of the cases are true

SameWith

C


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PHP Looping

Looping statements in PHP are

used to execute the same block ofcode a specified number of times.

SameWith

C


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Looping

Very often when you write code, you want the sameblock of code to run a number of times. You can uselooping statements in your code to perform this.

In PHP we have the following looping statements: while - loops through a block of code if and as long as a

specified condition is true do...while- loops through a block of code once, and then

repeats the loop as long as a special condition is true

for - loops through a block of code a specified number of times

foreach - loops through a block of code for each element in an

array

SameWith

C


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The while Statement

Example

The following example demonstrates a loop that will continue to run as long asthe variable i is less than, or equal to 5. i will increase by 1 each time theloop runs:

SameWith

C


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The do...while Statement

Example

The following example will increment the value of i at least once, and it willcontinue incrementing the variable i as long as it has a value of less than 5:

SameWith

C


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The for Statement

Example

The following example prints the text "Hello World!" five times:

SameWith

C


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Hands-on 3: Loop

Write a PHP program and create a variablenamed $age. Using control structures, test $age.

a. If $age is less than 18, it should print novote.

b. If $age is greater than or equal to 18, itshould print vote.

c. Using a loop of your choice, make the

program print happy birthday $age times (so if $age is 15, it will print 15 times)



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PHP Arrays

An array can store one or more

values in a single variable name.


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What is an array?

When working with PHP, sooner or later, youmight want to create many similar variables.

Instead of having many similar variables, youcan store the data as elements in an array.

Each element in the array has its own ID so thatit can be easily accessed.

There are three different kind of arrays: Numeric array- An array with a numeric ID key Associative array- An array where each ID key

is associated with a value Multidimensional array- An array containing

one or more arrays

N i A


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Numeric ArraysA numeric array stores each element with a numeric ID key.There are different ways to create a numeric array.

Example 1In this example the ID key is automatically assigned:

$names = array("Peter","Quagmire","Joe");

Example 2In this example we assign the ID key manually:

$names[0] = "Peter";$names[1] = "Quagmire";$names[2] = "Joe";

The ID keys can be used in a script:


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Associative ArraysAn associative array, each ID key is associated with a value.With associative arrays we can use the values as keys and assign values to them.

Example 1In this example we use an array to assign ages to the different persons:

$ages = array("Peter"=>32, "Quagmire"=>30, "Joe"=>34);

Example 2This example is the same as example 1, but shows a different way of creating the array:

$ages['Peter'] = "32";$ages['Quagmire'] = "30";$ages['Joe'] = "34";

The ID keys can be used in a script:

The code above will output:Peter is 32 years old.

M ltidi i l A


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Multidimensional Arrays

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. Example In this example we create a multidimensional array, with

automatically assigned ID keys:

$families = array("Griffin"=>array("Peter","Lois",Megan"),"Quagmire"=>array("Glenn"),"Brown"=>array("Cleveland","Loretta","Junior")

);

echo value is.$families[Brown][1];

M ltidi i l A


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Multidimensional Arrays

The array above would look like this if written to the output:

Array([Griffin] => Array([0] => Peter[1] => Lois[2] => Megan

)[Quagmire] => Array([0] => Glenn)

[Brown] => Array(

[0] => Cleveland[1] => Loretta[2] => Junior)

)

Th f h St t t


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The foreach Statement

The foreach statement is

used to loop through arrays. For every loop, the value of

the current array element isassigned to $value (and thearray pointer is moved by

one) - so on the next loop,you'll be looking at the nextelement.

Example

The following exampledemonstrates a loop that willprint the values of the givenarray.

H d 4 A


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Hands-on 4: Array

Write a PHP program and create an arrayof 10 integers named $array_of_scores.Using control structures, do the following:

a. Print all the integers. b. Get the sum of all the integers and print;

c. Among the integers, count the number

of odd and even integers, then, print;



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PHP Functions

The real power of PHP comes from itsfunctions.

In PHP - there are more than 700 built-in functions available.

C t PHP F ti


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Create a PHP Function

A function is a block of code that can be executedwhenever we need it.

Creating PHP functions:

All functions start with the word "function()"

Name the function - It should be possible to understandwhat the function does by its name. The name can startwith a letter or underscore (not a number)

Add a "{" - The function code starts after the openingcurly brace

Insert the function code

Add a "}" - The function is finished by a closing curlybrace

C t PHP F ti


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Create a PHP Function

Example

A simple function that writes my name when it is called:

U PHP F ti


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Use a PHP Function

Now we will use the function in a PHP script:

The output of the code above will be:

Hello world!My name is Kai Jim Refsnes.That's right, Kai Jim Refsnes is my name.


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PHP Functions Addingparameters

Our first function (writeMyName()) is a verysimple function. It only writes a static string.

To add more functionality to a function, we canadd parameters.

A parameter is just like a variable.

You may have noticed the parentheses after thefunction name, like: writeMyName().

The parameters are specified inside theparentheses.

PHP Functions - Adding


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Example 1

The following example will writedifferent first names, but the samelast name:

The output of the code above willbe:

My name is Kai Jim Refsnes. My name is Hege Refsnes. My name is Stale Refsnes.

PHP Functions - Adding


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Example 2

The following function has twoparameters:

The output of the code above willbe:

My name is Kai Jim Refsnes.

My name is Hege Refsnes! My name is Stle Refsnes...

PHP F ti R t l


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PHP Functions - Return values

Functions can also be used to return values.

Example

The output of the code above will be:

1 + 16 = 17

Hands on 5: Functions


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Hands-on 5: Functions

Write a PHP program and create the followingfunctions:

a. description(): print any statement to describe yourbest body feature, asset, or talent;

b. function to print the array of integers (fromhandson4).


Online References


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Online References.

To help you work with the activity, you canaccess the following online PHP tutorials:

a. http://www.tizag.com/phpT

b. http://www.learnphp-tutorial.com c. http://www.killerphp.com/videos/

d. http://www.w3schools.com

e. any other online PHP tutorials.
http://www.tizag.com/phpThttp://www.learnphp-tutorial.com/http://www.killerphp.com/videos/http://www.killerphp.com/videos/http://www.learnphp-tutorial.com/http://www.learnphp-tutorial.com/http://www.learnphp-tutorial.com/http://www.tizag.com/phpT

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Week 4- Intro to PHP

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