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Wednesday, October 26, 2011

PHP If...Else Statements

11:04 PM aldotdede No comments

Conditional statements are used to perform different actions based on different conditions.

Conditional Statements

Very often when you write code, you want to perform different actions for different decisions.
You can use conditional statements in your code to do this.
In PHP we have the following conditional statements:

if statement - use this statement to execute some code only if a specified condition is true
if...else statement - use this statement to execute some code if a condition is true and another code if the condition is false
if...elseif....else statement - use this statement to select one of several blocks of code to be executed
switch statement - use this statement to select one of many blocks of code to be executed

The if Statement

Use the if statement to execute some code only if a specified condition is true.

Syntax

if (condition) code to be executed if condition is true;

The following example will output "Have a nice weekend!" if the current day is Friday:

<html>
<body>

<?php
$d=date("D");
if ($d=="Fri") echo "Have a nice weekend!";
?>

</body>
</html>

Notice that there is no ..else.. in this syntax. The code is executed only if the specified condition is true.

The if...else Statement

Use the if....else statement to execute some code if a condition is true and another code if a condition is false.

Syntax

if (condition)
code to be executed if condition is true;
else
code to be executed if condition is false;

Example

The following example will output "Have a nice weekend!" if the current day is Friday, otherwise it will output "Have a nice day!":

<html>
<body>

<?php
$d=date("D");
if ($d=="Fri")
echo "Have a nice weekend!";
else
echo "Have a nice day!";
?>

</body>
</html>

If more than one line should be executed if a condition is true/false, the lines should be enclosed within curly braces:

<html>
<body>

<?php
$d=date("D");
if ($d=="Fri")
  {
  echo "Hello!<br />";
  echo "Have a nice weekend!";
  echo "See you on Monday!";
  }
?>

</body>
</html>

The if...elseif....else Statement

Use the if....elseif...else statement to select one of several blocks of code to be executed.

Syntax

if (condition)
  code to be executed if condition is true;
elseif (condition)
  code to be executed if condition is true;
else
  code to be executed if condition is false;

Example

The following example will output "Have a nice weekend!" if the current day is Friday, and "Have a nice Sunday!" if the current day is Sunday. Otherwise it will output "Have a nice day!":

<html>
<body>

<?php
$d=date("D");
if ($d=="Fri")
  echo "Have a nice weekend!";
elseif ($d=="Sun")
  echo "Have a nice Sunday!";
else
  echo "Have a nice day!";
?>

</body>
</html>

References from http://www.w3schools.com/php/

PHP Operators

11:01 PM aldotdede No comments

This section lists the different operators used in PHP.

Operator	Description	Example	Result
+	Addition	x=2 x+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

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
%=	x%=y	x=x%y

Comparison Operators

Operator	Description	Example
==	is equal to	5==8 returns false
!=	is not equal	5!=8 returns true
<>	is not equal	5<>8 returns true
>	is greater than	5>8 returns false
<	is less than	5<8 returns true
>=	is greater than or equal to	5>=8 returns false
<=	is less than or equal to	5<=8 returns true

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

References from http://www.w3schools.com/php/

PHP String Variables

10:55 PM aldotdede No comments

String Variables in PHP

String variables are used for values that contain characters.
In this chapter we are going to look at the most common functions and operators used to manipulate strings in PHP.
After we create a string we can manipulate it. A string can be used directly in a function or it can be stored in a variable.
Below, the PHP script assigns the text "Hello World" to a string variable called $txt:

<?php
$txt="Hello World";
echo $txt;
?>

The output of the code above will be:

Hello World

Now, lets try to use some different functions and operators to manipulate the string.

The Concatenation Operator

There is only one string operator in PHP.
The concatenation operator (.) is used to put two string values together.
To concatenate two string variables together, use the concatenation operator:

<?php
$txt1="Hello World!";
$txt2="What a nice day!";
echo $txt1 . " " . $txt2;
?>

The output of the code above will be:

Hello World! What a nice day!

If we look at the code above you see that we used the concatenation operator two times. This is because we had to insert a third string (a space character), to separate the two strings.

The strlen() function

The strlen() function is used to return the length of a string.
Let's find the length of a string:

<?php
echo strlen("Hello world!");
?>

The output of the code above will be:

The length of a string is often used in loops or other functions, when it is important to know when the string ends. (i.e. in a loop, we would want to stop the loop after the last character in the string).

The strpos() function

The strpos() function is used to search for a character/text within a string.
If a match is found, this function will return the character position of the first match. If no match is found, it will return FALSE.
Let's see if we can find the string "world" in our string:

<?php
echo strpos("Hello world!","world");
?>

The output of the code above will be:

The position of the string "world" in the example above is 6. The reason that it is 6 (and not 7), is that the first character position in the string is 0, and not 1.

References from http://www.w3schools.com/php/

PHP Variables

10:49 PM aldotdede No comments

Variables in PHP

Variables are used for storing values, like text strings, numbers or arrays.
When a variable is declared, it can be used over and over again in your script.
All variables in PHP start with a $ sign symbol.
The correct way of declaring a variable in PHP:

$var_name = value;

New PHP programmers often forget the $ sign at the beginning of the variable. In that case it will not work.
Let's try creating a variable containing a string, and a variable containing a number:

<?php
$txt="Hello World!";
$x=16;
?>

PHP is a Loosely Typed Language

In PHP, a variable does not need to be declared before adding a value to it.
In the example above, you see that you do not have to tell PHP which data type the variable is.
PHP automatically converts the variable to the correct data type, depending on its value.
In a strongly typed programming language, you have to declare (define) the type and name of the variable before using it.
In PHP, the variable is declared automatically when you use it.

Naming Rules for Variables

A variable name must start with a letter or an underscore "_"
A variable name can only contain alpha-numeric characters and underscores (a-z, A-Z, 0-9, and _ )
A variable name should not contain spaces. If a variable name is more than one word, it should be separated with an underscore ($my_string), or with capitalization ($myString)

References from http://www.w3schools.com/php/

PHP Syntax

10:44 PM aldotdede No comments

Basic PHP Syntax

A PHP scripting block always starts with <?php and ends with ?>. A PHP scripting block can be placed anywhere in the document.
On servers with shorthand support enabled you can start a scripting block with <? and end with ?>.
For maximum compatibility, we recommend that you use the standard form (<?php) rather than the shorthand form.

<?php
?>

A PHP file normally contains HTML tags, just like an HTML file, and some PHP scripting code.
Below, we have an example of a simple PHP script which sends the text "Hello World" to the browser:

<html>
<body>

<?php
echo "Hello World";
?>

</body>
</html>

Each code line in PHP must end with a semicolon. The semicolon is a separator and is used to distinguish one set of instructions from another.
There are two basic statements to output text with PHP: echo and print. In the example above we have used the echo statement to output the text "Hello World".
Note: The file must have a .php extension. If the file has a .html extension, the PHP code will not be executed.

--------------------------------------------------------------------------------------------------------------------------

Comments in PHP

In PHP, we use // to make a single-line comment or /* and */ to make a large comment block.

References from http://www.w3schools.com/php/

Instalasi Web Server Lokal

1:55 PM aldotdede No comments

Web Server Local ( localhost ) adalah sebuah aplikasi yang memberikan fasilitas kepada penggunanya untuk dapat mengakses Local Hosting . Web server local yang akan digunakan untuk menjalankan script PHP pada aplikasi ini adalah XAMPP, XAMPP merupakan tool yang menyediakan paket perangkat lunak ke dalam satu buah paket . Dengan menginstall XAMPP maka tidak perlu lagi melakukan instalasi dan konfigurasi web server apache, PHP, dan MySQL secara manual. XAMPP akan meginstalasi dan mengkonfigurasikanya secara otomatis untuk anda atau auto konfigurasi . Untuk menginstall XAMPP lakukan langkah – langkah berikut ini :

· Download XAMPP ! anda boleh download dari www.download.com lalu ketikkan kata “ xampp “ . Anda akan mendapatkan file installernya.

· Klik ganda ikon xampp-win32-1.4.12-installer.exe ( atau versi lainya ) .

· Setelah klik ganda pada installer tersebut , dan secara otomatis program akan menampilkan tampilan seperti Gambar 1.1 Klik Run.

Berikut ini adalah cara menginstall XAMPP.

Jalankan file xampp-win32-1.4.12-installer.exe (atau versi lainnya)
Kemudian akan tampil pilihan untuk memilih bahasa ketika proses instalasi berjalan. Silakan pilih bahasa Indonesian atau English, kecuali anda menguasai bahasa lainnya. Lihat Gambar 1.1

Gambar 1.1

Proses instalasi akan dimulai. Klik Maju untuk mulai. Lihat Gambar 1.2

Gambar 1.2

Akan muncul lisensi software. Silahkan membacanya jika anda mau, tetapi saya lebih suka untuk tidak membacanya karena terlalu banyak. Klik Saya Setuju untuk melanjutkan. Lihat Gambar 1.3

Gambar 1.3

Selanjutnya silakan anda pilih lokasi install untuk XAMPP. Kemudian klik install. Lihat Gambar 1.4

Gambar 1.4

Tunggu beberapa saat sampai proses instalasi sampai selesai. Lihat Gambar 1.5

Gambar 1.5

Sampai tahap ini, berarti kita sudah menginstal XAMPP. Langkah selanjutnya adalah menjalankan servicenya. Lihat Gambar 1.6

Gambar 1.6

Jalankan XAMPP Control Panel yang ada di desktop. Atau anda juga dapat menjalankan XAMPP Control Panel dari menu Start -> All Programs -> apachefriends -> xampp -> xampp control panel.

Nyalakan Apache dan Mysql dengan mengklik tombol Start. Buka web browser anda, lalu ketikkan http://localhost. Jika tampilannya seperti di bawah ini, maka apache sudah terinstall dengan xampp.

Sekedar informasi saja, document root milik XAMPP terletak pada folder E:\Program Files\apachefriends\xampp\htdocs. Hal ini disebabkan karena saya menginstall XAMPP pada folder E:\Program Files\apachefriends

Kelebihan PHP

1:37 PM aldotdede No comments

§ PHP mudah dibuat dan kecepatan akses tinggi.

§ PHP dapat berjalan dalam web server yang berbeda dalam sistem operasi yang berbeda pula.

§ PHP diterbitkan secara gratisan.

§ PHP merupakan bahasa yang dapat diletakkan dalam tag HTML.

§ Sistem database yang didukung PHP cukup banyak.

§ PHP termasuk server side programming.

Tipe Data PHP

1:33 PM aldotdede No comments

1. Integer : Yang termasuk dalam tipe data ini adalah bilangan bulat (tidak pakai koma). Contoh :

$a = 1234 // decimal

$b = -1234 // negative

$c = 0123 // octal

$d = 0x12 // heksadesimal

Pernyataan seperti $a = 1234 disebut pernyataan penugasan. Dalam contoh tersebut maksudnya adalah memberi nilai 1234 ke variable $a.

Pengertian PHP

1:31 PM aldotdede No comments

PHP : Hypertext Preprocessor adalah sebuah bahas script berjenis server side yang menyatu dengan HTML. Sintaks dan perintah-perintah yang dimasukkan akan sepenuhnya dijalankan dan dikerjakan oleh server dan disertai pada halaman HTML biasa. PHP bertujuan untuk membuat aplikasi-aplikasi yang dijalankan diatas taknologi Web. Dalam hal ini, aplikasi pada umumnya akan memberikan hasil pada Web browser, tetapi prosesnya secara keseluruhan dijalankan dan dikerjakan di Web server. PHP diciptakan oleh Rasmus Lerdorf.

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Wednesday, October 26, 2011

Conditional Statements

The if Statement

Syntax

The if...else Statement

Syntax

Example

The if...elseif....else Statement

Syntax

Example

String Variables in PHP

The Concatenation Operator

The strlen() function

The strpos() function

Variables in PHP

PHP is a Loosely Typed Language

Naming Rules for Variables

Basic PHP Syntax

Comments in PHP

Wednesday, May 4, 2011

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