Php

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PHP

-

Basic

Concepts

example simple html & php page

Below is an example of one of

Below is an example of one of the easiest PHP and HTML page tthe easiest PHP and HTML page that you can create and still follow webhat you can create and still follow web

standards. standards. PHP and HTML Code: PHP and HTML Code: <html> <html> <head> <head>

<title>My First PHP Page</title>

</head> </head> <body> <body> <?php <?php

echo "Hello World!";

?> ?> </body> </body> </html> </html> Display: Display: Hello World! Hello World!

If you save this file (e.g. helloworld.php) and place it on PHP

If you save this file (e.g. helloworld.php) and place it on PHP enabled server and load it up in your wenabled server and load it up in your webeb

browser, then you should see "Hello World!" displayed. If not, please check that you f

browser, then you should see "Hello World!" displayed. If not, please check that you followed our exampleollowed our example

correctly.

We used the PHP command

We used the PHP commandechoecho_{to write "Hello World!" and we will be talking in}_{to write "Hello World!" and we will be talking in}_{greater depth about how}_{greater depth about how} echo is special later on in this tutorial.

echo is special later on in this tutorial.

the semicolon!

As you may or may not have

As you may or may not have noticed in the above example, there was a noticed in the above example, there was a semicolon after the line of Psemicolon after the line of PHPHP

code. The semicolon signifies the end of a PHP

code. The semicolon signifies the end of a PHP statement and should never be forgotten. For example, if westatement and should never be forgotten. For example, if we

repeated our "Hello World!" code several times, then we would need to

repeated our "Hello World!" code several times, then we would need to place a semicolon at the end of place a semicolon at the end of

each statement. each statement. PHP and HTML Code: PHP and HTML Code: <html> <html> <head> <head>

<title>My First PHP Page</title>

</head>

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<body> <?php

echo "Hello World! "; echo "Hello World! "; echo "Hello World! "; echo "Hello World! "; echo "Hello World! "; ?>

</body> </html> Display:

Hello World! Hello World! Hello World! Hello World! Hello World! white space

As with HTML, whitespace is ignored between PHP statements. This means it is OK to have one line of PHP code, then 20 lines of blank space before the next line of PHP code. You ca n also press tab to indent your code and the PHP interpreter will ignore those spaces as well.

PHP and HTML Code: <html>

<head>

<title>My First PHP Page</title> </head>

<body> <?php

echo "Hello World!";

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?> </body> </html> Display:

Hello World!Hello World! This is perfectly legal PHP code.

php - variables

If you have never had any programming, Algebra, or scripting experience, then the concept of variables might be a new concept to you. A detailed explanation of variables is beyond the scope of this tutorial, but we've included a refresher crash course to guide you.

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A variable is a means of storing a value, such as text string "Hello World!" or the integer value 4. A variable can then be reused throughout your code, instead of having to type out the actual value over and over again. In PHP you define a variable with the following form:

$variable_name = Value;

If you forget that dollar sign at the beginning, it will not work. This is a common mistake for new PHP programmers!

Note: Also, variable names are case-sensitive, so use the exact same capitalization when using a variable. The variables $a_number and $A_number are different variables in PHP's eyes.

a quick variable example

Say that we wanted to store the values that we talked about in the above paragraph. How would we go about doing this? We would first want to make a variable name and then set that equal to the value we want. See our example below for the correct way to do this.

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<?php

$hello = "Hello World!"; $a_number = 4;

$anotherNumber = 8; ?>

Note for programmers: PHP does not require variables to be declared before b eing initialized.

php variable naming conventions

There are a few rules that you need to follow when choosing a name for your PHP variables.

PHP variables must start with a letter or underscore "_".

PHP variables may only be comprised of alpha-numeric characters and underscores. a-z, A-Z, 0-9, or _ . Variables with more than one word should be separated with underscores. $my_variable

Variables with more than one word can also be distinguished with capitalization. $myVariable

Login using PHP

:-1 2 3 4 5 6 7 8 9 10 11 12 <?php $USERS["username1"] = "password1"; $USERS["username2"] = "password2"; $USERS["username3"] = "password3"; function check_logged(){

global $_SESSION, $USERS;

if (!array_key_exists($_SESSION["logged"],$USERS)) { header("Location: login.php");

}; }; ?>

Using HTML and PHP together

:-PHP is not simply about outputting random values and simple text. You can seamlessly integrate :-PHP with HTML and output tables, formatted text, and more. You are probably wondering, what's the big deal about this? The deal is that you can control what is displayed on your site by integrating PHP and HTML. Best of all, PHP does not have its own set of formatting tags for you to learn. You use HTML. So let's get started. First, copy and paste the following code into a PHP page:

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<html> <body> <?php

print("Can gophers really code PHP?" ); ?>

</body> </html>

When you preview the page containing the above code, you should see the text "Can gophers really code PHP?" The text is not formatted at all. You will see the text displayed in whatever the default font is set to on your browser.

You don't have to suffer through dull, boring text though. You can format it - all inside the PHP tag area. Let's say you want to Bold the text. Add the HTML tags for bold, and tags to your text:

<?php

print("Can gophers really code PHP?" ); ?>

When you modify the code within your PHP tags with your Bold tags (see above code) and preview the page in your browser, you will find that the text is now bolded. Pretty cool, ehh? Now, let's try adding a horizontal line below the text. The html tag for displaying a horizontal line is <hr>. Let's add that tag to our code:

<?php

print("Can gophers really code PHP?" ); print("<hr>");

?>

Now, test this code. You should now see your text with a horizontal line displayed. Just remember, all we used was standard HTML tags using the print command.

A PHP session variable is used to store information about, or change settings for a user session. Session variables hold information about one single user, and are a vailable to all pages in one application.

PHP Session Variables

When you are working with an application, you open it, do some changes and then you close it. This is much like a Session. The computer knows who you are. It knows when you start the application and when you end. But on the internet there is one problem: the web server does not know who you are and what you do because the HTTP address doesn't maintain state.

A PHP session solves this problem by allowing you to store user information on the server for later use (i.e. username, shopping items, etc). However, session information is temporary and will be deleted after the user has left the website. If you need a permanent storage you may want to store the data in a database.

Sessions work by creating a unique id (UID) for each visitor and store variables based o n this UID. The UID is either stored in a cookie or is propagated in the URL.