if (expr)
   statement

The general format of if construct is like shown below:

if (expr1) {
   //  statement if expr 1 true
} else if (expr2) {
   // statement if expr 2 true
} else {
   // statement if expr 1 and 2 false
}

You may find useful documentation about if construct, else and else if in php.net.

But how if you only need two condition to produce a word or digit, and then save it into a variable or just echo it? You may write it like shown below:

if ($status = '0')
   echo 'Draft';
else
   echo 'Published';

In code example above, you need to write four lines. Compare with code shown below:

echo $status == '0' ? 'Draft' : 'Published';

The syntax is show below

echo expr ? 'value if true' : 'value if false';

You may change echo with variable assignment such as:

$var = expr ? 'value if true' : 'value if false';

Easy right? It cuts down four lines into one line only.

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Adobe Flex Builder 3 Professional

Flex is a highly productive, free open source framework for building and maintaining expressive web applications that deploy consistently on all major browsers, desktops, and operating systems. While Flex applications can be built using only the free open source framework, developers can use Adobe® Flex® Builder™ software to dramatically accelerate development.

If you want to know more about Flex, you may visit its website flex.org. I won’t tell you about flex. I just wanna share my experience. As you read before, you may develop Flex application using only the free open source framework. In frankly speaking, you should work hard to develop it from the scratch. If you want the easier way, you need to use Adobe Flex Builder. The problem is, you should pay to use it. Of course, for a great software, we need to pay. It doesn’t matter if you are a software house or professional that make money from developing application using that software. But if you are a student that need to learn Flex? A student doesn’t make money but only need to learn.

For student, don’t worry. Adobe is very kind to student and faculty. They give Adobe Flex Builder for free. It sounds great doesn’t it? Yes. It’s very great! And I’m one of the lucky guy who get the Adobe Flex Builder for free.

How to get it? Easy. Remember, you need to be honest. You should be a student or a faculty. Adobe Flex Builder 3 Pro is available for free to all education customers. This includes all students, faculty and staff of eligible education institutions.

Proof of Eligibility
To receive the product, you must upload a valid proof of eligibility to get the serial numbers to activate the product. Valid proofs of eligibility are:

1. a student ID showing current enrollment,
2. a Faculty ID showing current employment
3. an employee ID showing current employment, or
4. a letter on an educational institution letterhead stating that you are either a current student, a current faculty member or a current employee of the institution.

Terms and conditions
The education version is only available to education customers and is not meant for distribution to institutions, organizations or people outside the authorized educational institution. For additional information on eligibility, please refer to their FAQ.

After submitting your proof of eligibility, you need to download the Adobe Flex Builder 3 Professional trial version (60 days). They will check it within two weeks. I suggest you to use your university email address. If you are approved, they will send you a serial number to activate your Flex Builder 3 Professional. Then, you can smile.. :)

OK, what are you waiting for? come on get Adobe Flex Builder 3 Professional for free.. :)

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1. Facebook Addict, a Free WordPress Theme

1) You need to update Ubuntu Repository. Type this command:

sudo apt-get update

Just wait till your Ubuntu Repository updated.

2) Now it’s time to install Java. If you are developer, you need JDK (Java Development Kit), but if not, you only need JRE (Java Runtime Environment). I will install JDK 6 in my Ubuntu.

for JDK, here is the command:

sudo apt-get install sun-java6-jdk sun-java6-plugin

for JRE, here is the command:

sudo apt-get install sun-java6-jre sun-java6-plugin

3) After that, run command:

sudo update-java-alternatives -s java-6-sun

Then add the line “/usr/lib/jvm/java-6-sun” to the top of /etc/jvm file.

4) Check your Java installation using these commands:

java -version

the output:

java version "1.6.0_03"
Java(TM) SE Runtime Environment (build 1.6.0_03-b05)
Java HotSpot(TM) Client VM (build 1.6.0_03-b05, mixed mode, sharing)

if you install JDK, check Java compiler using:

javac -version

the output:

javac 1.6.0_03

5) You’re done!

Related posts:

1. Java & MySQL Connection
2. How to Create Environment Variables in Linux

System Requirement Checking on Magento Commerce

We could use phpinfo() function to view which extensions have been loaded. The php.ini file is used to configure it. We could find it in PHP installation directory. If you use XAMPP, PHP configuration can be found in [XAMPP's Installation directory]/apache/bin.

To edit it, simply use a text editor (such as notepad). Find which extension will be activated. For example, in magento case, it needs curl and mcrypt extensions to be activated. All we need is finding lines that have words php_curl.dll and php_mcrypt.dll in php.ini. As default, the configuration for those extensions is:

;extension=php_curl.dll
;extension=php_mcrypt.dll

To activate them we need to delete semicolon in the first character of those two lines. If we have done, restart apache and check extensions status using phpinfo().

PHP Info

Question: why does we delete that semicolon?
In PHP configuration file (you will find the same thing in apache configuration), a semicolon is used to mark that the line after that will not be executed. Because of that, the programmers use it to make comments.

Becareful if you need to edit configuration file. If you make a mistake, possibly your PHP won’t work well. Always make a configuration file backup before make changes, in order to make sure it would be easy to restore the configuration file if something wrong happens.

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Analysis:
We could make a link directly to the file location. Example:

<a href="myebook.pdf">Download MyEbook</a>

What happen if the link above clicked? It depends to the visitors’ browser. If the plugin to read pdf is installed, then browser will open that file inside browser. But, how if there’s no pdf reader plugin? Then a save file dialog box appear. We could save that file.

A problem is done if the visitors don’t have pdf reader plugin. But what about the visitors who have it? Of course the problem is not solved. Another problem is the visitors know the file location,  so it allows the visitors to download the file directly (download it directly by typing/copy paste the URL in the browser, without clicking from link given).

Solution:
We need a bit code (PHP) to solve this problem.

The code to avoid direct download is shown below:

You need to concern to this line:

header('Content-Disposition: attachment; filename="myebook.pdf"');

This line forces browser to show save dialog box for “myebook.pdf” although there’s pdf reader plugin in the browser.

To change file type (exe or zip), we need to change Content-Type only. Here are the lists:

// archives
application/zip

// documents
application/pdf
application/msword
application/vnd.ms-excel
application/vnd.ms-powerpoint
// executables
application/octet-stream

// images
image/gif
image/png
image/jpeg

// audio
audio/mpeg
audio/x-wav

// video
video/mpeg
video/quicktime
video/x-msvideo

File starts downloading from the line after this line:

// start downloading from here

There’s a question. Why do we need to avoid direct download? The purpose is to check how many times a file has been downloaded. If the visitors are allowed to download files directly, I’m sure it will be difficult to know how many times a file is downloaded. If you don’t need to check how many times the visitors download your files, you could use both direct download or indirect download.

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1. Creating Database in MySQL

[ Download MySQL Connector ]

Extract downloaded file (file type: *.jar). Copy that file to directory [jre installation]/lib/ext/. Ok, your Java application is ready to connect with MySQL.

Testing
Code below is used to connect between Java and MySQL.
/*
* DBConnection.java
*
* Created on 29 September 2007, 11:41
*
*/

import java.sql.*;

/**
*
* @author Dani Gunawan
*/
public class DBConnection {

/** Creates a new instance of DBConnection */
public DBConnection() {
}

public Connection connect() {
Connection conn = null;

try
{
String userName = “root”;
String password = “”;
String url = “jdbc:mysql://blog.danigunawan.com/test”;
Class.forName (“com.mysql.jdbc.Driver”).newInstance ();
conn = DriverManager.getConnection (url, userName, password);
} catch (Exception e) {
e.printStackTrace();
conn = null;
} finally {
if (conn != null)
{
try
{
conn.close ();
}
catch (Exception ex) {
ex.printStackTrace();
}
}
}

return conn;
}
}

Code below is used to test the database connection.

/**
* TesConnection.java
*/
import java.sql.*;

public class TesConnection {

public static void main(String args[]) {

Connection dbcon = new DBConnection().connect();

if (dbcon != null) {
System.out.println(“Database connection is successfully created”);
} else {
System.out.println(“Database connection isn’t successfully created”);
}
}

}

How to Use Them?
Put those two source in the same directory. Compile DBConnection.java and TesConnection.java respectively.

javac DBConnection.java
javac TesConnection.java

If you want to compile all of them, use wildcard asterisk (*).

javac *.java

Run TesConnection:

java TesConnection

If the result:

Database connection is successfully created

Then your database is has been connected. But if:

Database connection isn’t successfully created

means your Java application isn’t connected yet with the database.
Possibility:
- MySQL isn’t installed yet
- Database hasn’t been created yet (or maybe wrong database name)
- Wrong database user or password

Both source can be downloaded from link below:

[ Download example file ]

P.S.:
Code had been tested in Windows XP SP 2 Operating System, never been done in other operating systems.

Related posts:

1. How To Install Java in Linux Ubuntu
2. Creating Database in MySQL
3. After Oracle Bought Sun

So, how does C++ compiler differentiate those two methods? C++ compiler observes the amount, data type and argument sequence. It’s clear that the compiler use parameters to differentiate methods which have the same name. Not differentiate them with their return type.

// method multiply with three arguments (number1, number2 dan number3)
int multiply(int number1, int number2, int number3) {
   return number1*number2*number3;
}

// method showGrade has a char data type argument
void showGrade(char grade) {
   cout << "Grade (in letter): " << grade;
}

// method showGrade has a int data type argument
void showGrade(int grade) {
   cout << "Grade (in number): " << grade;
}

// method multiply with data type number1 is int
// and number2 is double
double multiply(int number1, double number2) {
   return number1*number2;
}

// method multiply with data type number1 is double
// and number2 is int
double multiply(double number1, int number2) {
   return number1*number2;
}

// return type: int
int countAge(int age) {
   return age + 2;
}

// return type: void
void countAge(int age) {
   cout<<"Student age after two years = "<<age+2;
}

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Expert in mathematics?
Hmm… not really. Not all mathematics lesson should be known. No need to master Integral or imaginary. But there are a few lesson you should master them. They are logics, binary, hexadecimal.

Know all programming languages?
Not all programming languages. The important thing is know the basic programming technique.

Choose a favourite or populer programming language, then memorize all syntax?
Are you crazy..? No need to do that!

Know all features of a programming language?Menguasai seluruh fitur sebuah bahasa pemrograman?
Ooops… can you do it?t

So, what do we need???

• Know algorithm (step-by-step in finishing a problem)
• Know logics, such as “AND”, “OR”, “NOT”
• Know binary and hexadecimal
• Desire to learn programming
• Trial and Error
• Carefulness
• Talent. Some people say that to be a programmer, you need talent. But I say, our talent will  be sharp along with our practice in programming, although we make a simple application only.

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