PHP For Loops

So what’s a loop then? A loop is something that goes round and round. If I told you to move a finger around in a loop, you’d have no problem with the order (unless you have no fingers!) In programming, it’s exactly the same. Except a programming loop will go round and round until you tell it to stop. You also need to tell the programme two other things - where to start your loop, and what to do after it’s finished one lap (known as the update expression).
You can programme without using loops. But it’s an awful lot easier with them. Consider this.
You want to add up the numbers 1 to 4: 1 + 2 + 3 + 4. You could do it like this:

$answer = 1 + 2 + 3 + 4;
print $answer;

Fairly simple, you think. And not much code, either. But what if you wanted to add up a thousand numbers? Are you really going to type them all out like that? It’s an awful lot of typing. A loop would make life a lot simpler. You use them when you want to execute the same code over and over again.
We'll discuss a few flavours of programming loops, but as the For Loop is the most used type of loop, we'll discuss those first.

For Loops

Here’s a PHP For Loop in a little script. Type it into new PHP script and save your work. Run your code and test it out.

<?PHP

$counter = 0;
$start = 1;

for($start; $start < 11; $start++) {

$counter = $counter + 1;
print $counter . "<BR>";

}

?>

How did you get on? You should have seen the numbers 1 to 10 printed on your browser page.
The format for a For Loop is this:

for (start value; end value; update expression) {

}

The first thing you need to do is type the name of the loop you’re using, in this case for. In between round brackets, you then type your three conditions:
Start Value
The first condition is where you tell PHP the initial value of your loop. In other words, start the loop at what number? We used this:

$start = 1;

We’re assigning a value of 1 to a variable called $start. Like all variables, you can make up your own name. A popular name for the initial variable is the letter i . You can set the initial condition before the loop begins, like we did:

$start = 1;

for($start; $start < 11; $start++) {

Or you can assign your loop value right in the For Loop code:

for($start = 1; start < 11; start++) {

The result is the same – the start number for this loop is 1

End Value
Next, you have to tell PHP when to end your loop. This can be a number, a Boolean value, a string, etc. Here, we’re telling PHP to keep going round the loop while the value of the variable $start is Less Than 11.

for($start; $start < 11; $start++) {

When the value of $start is 11 or higher, PHP will bail out of the loop.

Update Expression
Loops need a way of getting the next number in a series. If the loop couldn’t update the starting value, it would be stuck on the starting value. If we didn’t update our start value, our loop would get stuck on 1. In other words, you need to tell the loop how it is to go round and round. We used this:

$start++

In a lot of programming language (and PHP) the double plus symbol (++) means increment (increase the value by one). It’s just a short way of saying this:

$start = $start + 1

You can go down by one (decrement) by using the double minus symbol (--), but we won’t go into that.

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So our whole loop reads “Starting at a value of 1, keep going round and round while the start value is less than 11. Increase the starting value by one each time round the loop.”
Every time the loop goes round, the code between our two curly brackets { } gets executed:

$counter = $counter + 1;
print $counter . "<BR>";

Notice that we’re just incrementing the counter variable by 1 each time round the loop, exactly the same as what we’re doing with the start variable. So we could have put this instead:

$counter ++

The effect would be the same. As an experiment, try setting the value of $counter to 11 outside the loop (it’s currently $counter = 0). Then inside the loop, use $counter- - (the double minus sign). Can you guess what will happen? Will it crash, or not? Or will it print something out? Better save your work, just in case!

Using WHERE to limit data in MySql and PHP

You can add a WHERE part to your SQL. But before you do, make sure you read the security section.

Using WHERE limits the records returned from a SQL statement. Most of the time, you don’t want to return all the records from your table. Especially if you have a large number of records. This will just slow things down unnecessarily. Instead, use WHERE. In the SQL below, we’re using WHERE to bring back only the matching records from the AddressBook table:

$SQL = “SELECT * FROM AddressBook WHERE email = ‘me@me.com’ “;

When the following code is run, only the records that have an email field of me@me.com will be returned.

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You can specify more fields in your WHERE clause:

$SQL = “SELECT * FROM AddressBook WHERE First_Name = ‘Bill’ AND Surname = ‘Gates'”;

In the SQL statement above, we’ve used the AND operator as well. Only records that have First_Name value of Bill AND a Surname value of Gates will be returned.

You can also use the operators you saw in the variables section:

$SQL = “SELECT * FROM AddressBook WHERE ID >= ’10’ “;

In this SQL statement, we’re specifying that all the records from the AddressBook table should be returned WHERE the ID column is greater than or equal to 10.

Getting the hang of WHERE can really speed up your database access, and is well worth the effort. An awareness of the security issues involved is also a must.

In the next sections, we’ll take you through some fuller projects, and explain the code, and the things you need to consider when working on bigger projects like this. First up is a username and password system.

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Create a database for a Survey App

This lesson is part of an ongoing Survey/Poll tutorial. The first part is here: Build your own Survey/Poll, along with all the files you need.

In the previous part of this lesson, you opened the phpMyAdmin screen. With this still open, click on “Please select a database“. Have a look at the items on the drop down list. You should see one called surveytest:

If you can’t see surveytest there, it means you haven’t copied the surveytest folder to the correct place.

If you can see surveytest, select it from the drop down list. You should see the names of two tables appear:

Click on tblQuestions, and you’ll see the Structure for this Table (it’s too big to fit on this page, so click below to see it):

The Structure for the tblQuestions Table (opens in a new window – 59K

Under the Table heading, you’ll see the two tables in this database: answers and tblQuestions. Click on the Browse icon for tblQuestions, as in the image below:

You will be taken to the Field names and Rows in the table:

The Field names run from left to right, and are important. They are:

QID
Question
qA
qB
qC

The tblQuestions table above has four rows of data, one for each question. The QID field is the one to pay attention to. The values in the sample table are q1, q2, q3, and q4. This QID field is the Primary Key in this table. This means that the data in this field has to be unique. You can then use this QID field to identify each row in the table. This same field, QID, is also in the answers table, along with the qA, qB, qC fields. This allows you to select all the records in both tables based on the QID field. You just pull all the records that match. For example, you can say “Select all the records in both tables where the QID field equals q1″.

Take a look at the answers table by clicking the link on the left hand side. Then click on Browse at the top. You should see this:

In the answers table, the unique field (the primary key) is the ID field. This is just an auto incrementing number that you used in an earlier section. You don’t have to worry about this field. But notice that the QID field is also there, along with the same values from the tblQuestions table: q1, q2, q3, and q4. This matching QID field in the answers table is something called a foreign key, in database terminology. Joining data from a primary key in one table to a foreign key in another is common technique in database creation. You do this when you want to keep data separate, and to avoid having too many fields in a single table. It also speeds things up. In our example database, we can keep the questions and answers separate.

(NOTE: If you have some knowledge about databases, you’ll know about Referential Integrity. Unfortunately, phpMyAdmin doesn’t enforce this. So if you delete a row from one table, the corresponding row in another table won’t get deleted – you have to code for that yourself!)

The A, B, and C fields in the answers table record how many people voted for each option of your question. So, for question four (q4) 28 people voted for option A, 127 people voted for option B, and 52 people voted for option C. If you look at the matching row (q4) in the tblQuestions table you’ll see that the question was: Do you believe in UFOs? (These answers were entered by us – it’s not real data!)

Now that you have a good idea about how the database works, let’s go through the code that sets a question.

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10 Advanced PHP Tips To Improve Your Programming

PHP programming has climbed rapidly since its humble beginnings in 1995. Since then, PHP has become the most popular programming language for Web applications. Many popular websites are powered by PHP, and an overwhelming majority of scripts and Web projects are built with the popular language.

Because of PHP’s huge popularity, it has become almost impossible for Web developers not to have at least a working knowledge of PHP Training in Jaipur . This tutorial is aimed at people who are just past the beginning stages of learning PHP and are ready to roll up their sleeves and get their hands dirty with the language. Listed below are 10 excellent techniques that PHP developers should learn and use every time they program. These tips will speed up proficiency and make the code much more responsive, cleaner and more optimized for performance.

1. Use an SQL Injection Cheat Sheet

A list of common SQL injections.

SQL injection is a nasty thing. An SQL injection is a security exploit that allows a hacker to dive into your database using a vulnerability in your code. While this article isn’t about MySQL, many PHP programs use MySQL databases with PHP, so knowing what to avoid is handy if you want to write secure code.

Furruh Mavituna has a very nifty SQL injection cheat sheet that has a section on vulnerabilities with PHP and MySQL. If you can avoid the practices the cheat sheet identifies, your code will be much less prone to scripting attacks.

2. Know the Difference Between Comparison Operators

PHP’s list of comparison operators.

Comparison operators are a huge part of PHP, and some programmers may not be as well-versed in their differences as they ought. In fact, an article at I/O reader states that many PHP developers can’t tell the differences right away between comparison operators. Tsk tsk.

These are extremely useful and most PHPers can’t tell the difference between == and ===. Essentially, == looks for equality, and by that PHP will generally try to coerce data into similar formats, eg: 1 == ‘1′ (true), whereas === looks for identity: 1 === ‘1′ (false). The usefulness of these operators should be immediately recognized for common functions such as strpos(). Since zero in PHP is analogous to FALSE it means that without this operator there would be no way to tell from the result of strpos() if something is at the beginning of a string or if strpos() failed to find anything. Obviously this has many applications elsewhere where returning zero is not equivalent to FALSE.

Just to be clear, == looks for equality, and === looks for identity. You can see a list of the comparison operators on the PHP.net website.

3. Shortcut the else

It should be noted that tips 3 and 4 both might make the code slightly less readable. The emphasis for these tips is on speed and performance. If you’d rather not sacrifice readability, then you might want to skip them.

Anything that can be done to make the code simpler and smaller is usually a good practice. One such tip is to take the middleman out of else statements, so to speak. Christian Montoya has an excellent example of conserving characters with shorter else statements.

Usual else statement:

if( this condition )
{
$x = 5;
}
else
{
$x = 10;
}

If the $x is going to be 10 by default, just start with 10. No need to bother typing the else at all.

$x = 10;
if( this condition )
{
$x = 5;
}

While it may not seem like a huge difference in the space saved in the code, if there are a lot of else statements in your programming, it will definitely add up.

4. Drop those Brackets

Dropping brackets saves space and time in your code.

Much like using shortcuts when writing else functions, you can also save some characters in the code by dropping the brackets in a single expression following a control structure. Evolt.org has a handy example showcasing a bracket-less structure.

if ($gollum == 'halfling') {
$height --;
}

This is the same as:

if ($gollum == 'halfling') $height --;

You can even use multiple instances:

if ($gollum == 'halfling') $height --;
else $height ++; 
 
if ($frodo != 'dead')
echo 'Gosh darnit, roll again Sauron';
 
foreach ($kill as $count)
echo 'Legolas strikes again, that makes' . $count . 'for me!';

5. Favour str_replace() over ereg_replace() and preg_replace()

Speed tests show that str_replace() is 61% faster.

In terms of efficiency, str_replace() is much more efficient than regular expressions at replacing strings. In fact, according to Making the Web, str_replace() is 61% more efficient than regular expressions like ereg_replace() and preg_replace().

If you’re using regular expressions, then ereg_replace() and preg_replace() will be much faster than str_replace().

6. Use Ternary Operators

Instead of using an if/else statement altogether, consider using a ternary operator. PHP Value gives an excellent example of what a ternary operator looks like.

//PHP COde Example usage for: Ternary Operator
$todo = (empty($_POST[’todo’])) ? ‘default’ : $_POST[’todo’]; 
 
// The above is identical to this if/else statement
if (empty($_POST[’todo’])) {
$action = ‘default’;
} else {
$action = $_POST[’todo’];
}
?>

The ternary operator frees up line space and makes your code less cluttered, making it easier to scan. Take care not to use more than one ternary operator in a single statement, as PHP doesn’t always know what to do in those situations.

7. Memcached

Memcached is an excellent database caching system to use with PHP.

While there are tons of caching options out there, Memcached keeps topping the list as the most efficient for database caching. It’s not the easiest caching system to implement, but if you’re going to build a website in PHP that uses a database, Memcached can certainly speed it up. The caching structure for Memcached was first built for the PHP-based blogging website LiveJournal.

PHP.net has an excellent tutorial on installing and using memcached with your PHP projects.

8. Use a Framework

CakePHP is one of the top PHP frameworks.

You may not be able to use a PHP framework for every project you create, but frameworks like CakePHP, Zend, Symfony and CodeIgniter can greatly decrease the time spent developing a website. A Web framework is software that bundles with commonly needed functionality that can help speed up development. Frameworks help eliminate some of the overhead in developing Web applications and Web services.

If you can use a framework to take care of the repetitive tasks in programming a website, you’ll develop at a much faster rate. The less you have to code, the less you’ll have to debug and test.

9. Use the Suppression Operator Correctly

The error suppression operator (or, in the PHP manual, the “error control operator“) is the @ symbol. When placed in front of an expression in PHP, it simply tells any errors that were generated from that expression to now show up. This variable is quite handy if you’re not sure of a value and don’t want the script to throw out errors when run.

However, programmers often use the error suppression operator incorrectly. The @ operator is rather slow and can be costly if you need to write code with performance in mind.

Michel Fortin has some excellent examples on how to sidestep the @ operator with alternative methods. Here’s an example of how he used isset to replace the error suppression operator:

if (isset($albus))  $albert = $albus;
else                $albert = NULL;

is equivalent to:

$albert = @$albus;

But while this second form is good syntax, it runs about two times slower. A better solution is to assign the variable by reference, which will not trigger any notice, like this:

$albert =& $albus;

It’s important to note that these changes can have some accidental side effects and should be used only in performance-critical areas and places that aren’t going to be affected.

10. Use isset instead of strlen

Switching isset for strlen makes calls about five times faster.

If you’re going to be checking the length of a string, use isset instead of strlen. By using isset, your calls will be about five times quicker. It should also be noted that by using isset, your call will still be valid if the variable doesn’t exist. The D-talk has an example of how to swap out isset for strlen:

PHP Training When You Have to Fulfill a Dream of Developing Your Own Site

You can find out more about what you need to do when you can finish the training for PHP and then start with your own web sites or you can work for some big enterprises so that your created or developed site will do better with the customers.

The PHP is a scripting language and is suitable for you if you like to work with the web development to create better web sites for yourself or for other companies, professionally. There are different ways you can start with the learning of the language through the PHP Course given by different centers and you can check out their syllabus so that you can start with the training. The professional expanse for such training can be vast in these days where the internet is the main thing and every business are based on the way you can develop the web site to gain the trust of the web traffic.

Effective reasons for going for such training
The PHP training is effective for people who are good at understanding the different languages for programming. You can make the life of the web site owner easier by the knowledge of the site building and administration. The site will grow larger day by day and you need to find out more effective ways to make the site attractive and informative for the customers of the site owner. You can also have a dream to build your own site so that you can start the online business through it. So if you can go through the complete training, you have a scope of professional acclimatization from different companies. You can also start earning decent profit for your business. These are the principal reason why you need to go for such training with the center. 

PHP knowledge will help in web development
The PHP knowledge can give you specific confidence to work with the modern companies for developing the new sites. The site development through programming language like PHP and HTML makes the business of the owner more efficient and profitable. The PHP training will give you scope to give ways to new ideas and bring about new changes that will give customers an intimate feel and comfort. The language is used by most of programmers, and it gives a better alternative for Microsoft ASP. 

Working as a professional when you know PHP
If you want to work with this language after you have completed the PHP training, you will find the working from a professional point of view is easier as they can be embedded in the codes of HTML. You can use the PHP with other software applications too, but you will find ways to work effectively by trying out different methods to bring perfect design. As the site grows larger, you will have to work more with PHP for bringing the reputable effect on your site. 

You will be able to incorporate changes by using include function of the software, and you can also use the server side language for scripting to create and evolve different interactive pages that will look sophisticated and professional for the site. These changes that you would love to create will need the knowledge that you can earn from a course from a PHP training center. The center often helps you with proper placements and you can start with the field work right after you finish with the course. 

Why PHP for Making Dynamic Website Development?

PHP is one of the most popular site for creating Dynamic website. It offers a lot of benefits. If you are ready to add dynamic content to your webpages, consider the use of PHP Training. It's free, easy to learn and integrates well across many platforms and with various software programs. There are tons of tutorials available on the net.

Free and Capable
PHP is open source and it can be updated and developed by developers. Therefore, all its components are free to use and distribute. We can develop any type of website using PHP and it can handle with lot of traffic. Facebook, Twitter, Wikipedia and many other websites use it as their framewok. It can do anything that CGI programs because it is server-side scripting language.

Easy and Platform Independent
Syntax of PHP code is easy to understand. The developer who knows C/C++ they can easily learn PHP and code is embedded in the HTML source code. PHP provides high compatibility with leading operating systems and web servers such as thereby enabling it to be easily deployed across several different platforms. It can be run on all major operating systems like Linux, UNIX, Mac OS and Windows.

Supports All Major Web Servers and Major Databases
It supports all major web servers like Apache, Microsoft IIS, Netscape, personal webserver, iPlanet server and all major databases like MySQL, dBase, IBM DB2, InterBase, FrontBase, ODBC, PostgreSQL, SQLite, etc.

Quick Developments and secure
It uses its own memory space so that decreases the loading time and workload from the server. The processing speed is fast. PHP offers security as well that helps prevent malicious attacks. These security levels can be adjusted in the.ini file. It can develop applications like Ecommerce, CRM, CMS and Forums very fast. And It has multiple layers of security to prevent threats and malicious attacks.

Large Communities, Proven and Trusted
It has a large community of developers who regular and timely updates tutorials, documentation, online help and FAQs. It is being used since close to two decades now since its inception in 1995. It is trusted by thousands of websites and developers and the list is increasing day by day. It has also proven its capability and versatility by developing and maintaining some of the most highly visited and popular websites.

Talent Availability
You can hire PHP programmers more easily than any other language programmers since so many people know the language.

Php Developement Intorduction

PHP is a scripting language designed to fill the gap between SSI (Server Side Includes) and Perl, intended for the web environment. Its principal application is the implementation of web pages having dynamic content. PHP has gained quite a following in recent times, and it is one of the frontrunners in the Open Source software movement. Its popularity derives from its C-like syntax, and its simplicity. The newest version of PHP is 5.5 and it is heavily recommended to always use the newest version for better security, performance and of course features.

If you've ever been to a website that prompts you to login, you've probably encountered a server-side scripting language. Due to its market saturation, this means you've probably come across PHP. PHP was designed by Rasmus Lerdorf to display his resume online and to collect data from his visitors.

To Know more about PHP Institute in Jaipur

Basically, PHP allows a static webpage to become dynamic. "PHP" is an acronym that stands for "PHP: Hypertext Preprocessor". The word "Preprocessor" means that PHP makes changes before the HTML page is created. This enables developers to create powerful applications which can publish a blog, remotely control hardware, or run a powerful website such as Wikipedia or Wikibooks. Of course, to accomplish something such as this, you need a database application such as MySQL.

Before you embark on the wonderful journey of Server Side Processing, it is recommended that you have a basic understanding of the HyperText Markup Language (HTML). But PHP can also be used to build GUI-driven applications for example by using PHP-GTK.

A single PHP file is like using magic on a webpage. In HTML, you have a standard page that is sent to anyone that visits your website. With PHP, you can dynamically change the page based on each individual user. Honestly, learn PHP and put it to the test. You will be extremely impressed with what an open source programming language can accomplish. I am not going to tell you that PHP is the best server side language that is out there, but it is the best for a tight budget or a beginner (Sorry, after coding with ColdFusion, I can no longer say PHP is my favorite).

What exactly does PHP do?

It can create custom content based on different variables

It is excellent at tracking user information

It can write or read information to databases, if partnered with a database language

It can run on any type of platform and server

 

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