Welcome to one of the most widely used programming languages
used to develop web applications.
“PHP: hypertext preprocessor “programming language which
allows web developers to create dynamic content that interacts with the
databases.
PHP uses simple code, anyone with the basic programming
knowledge can learn and work on PHP. It is a server-side scripting language used
to develop dynamic web pages
PHP can integrate with many databases like MySQL,
Sybase, ORACLE, Microsoft SQL Server.
This blog post will help you understand the basics of PHP
First, see what can we do with PHP?
· In PHP
we can restrict the user access to some web pages as per demand.
· PHP can
encrypt data
· In PHP
we can easily add, delete and modify data with the database
· PHP can
set cookies
· It allows
execution of inline code
· It’s easy
to scale up
PHP Installation Prerequisites
To start developing with PHP all we need is the three most
important component installed.
Web server – PHP can work virtually with all webserver
including Microsoft IIS.
Database – PHP can work with different databases but
commonly uses MySQL.
PHP parser – As PHP is a server-side scripting language so
to process the instructions a parser must be installed to generate HTML output
which is then sent to the server.
Installation
To install PHP follow the given video link in order to know step by step instructions
Why to
Use PHP?
PHP is easy to understand.
It’s an open-source language.
It’s cost-effective for the organization.
PHP is a server-side scripting language which means you only have to install it on
the server and clients can easily use the resources without having installed.
PHP is a cross-platform that means you can deploy your application on
different operating systems such as Linux, Mac OS, windows, etc.
PHP is a cross-platform that means you can deploy your application on
different operating systems such as Linux, Mac OS, windows, etc.
File
Extension in PHP
To identify any PHP file we have saved our file with .php
extension.
PHP can easily work with HTML and is embedded into the HTML
code.
For e.g.
<HTML>
<PHP CODE>
</HTML>
Server interprets the PHP code and results as HTML code to
the web browsers.
Server identifies the PHP code within the HTML code with the PHP tags.
PHP is a case sensitive language.
PHP scripts are executed on the server.
Server identifies the PHP code within the HTML code with the PHP tags.
PHP is a case sensitive language.
PHP scripts are executed on the server.
PHP Variables
PHP
variables are used to hold values or expressions.
A variable can have a short name, like x, or a more descriptive name,
like carName.
Rules for PHP variable names:
- Variables in PHP starts with a $ sign, followed by the name of the variable
- The variable name must begin with a letter or the underscore character
- A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
- A variable name should not contain spaces
- Variable names are case sensitive (y and Y are two different variables)
Creating (Declaring) PHP
Variables
PHP
has no command for declaring a variable.
A
variable is created the moment you first assign a value to it:
$myCar="Volvo";
After the
execution of the statement above, the variable myCar will hold
the value Volvo.
Tip: If
you want to create a variable without assigning it a value
Then you
assign it the value of null.
Let's create a
variable containing a string, and a variable containing a number:
<?php
$txt="Hello World!";
$x=16;
?>
$txt="Hello World!";
$x=16;
?>
Note: When
you assign a text value to a variable put quotes around the value.
PHP is a Loosely Typed
Language
In PHP, the variable does not need to be declared before adding value to it.
In the example
above, notice that we did 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.
PHP Variable Scope
The scope of a
variable is the portion of the script in which the variable can be referenced.
PHP has four
different variable scopes:
- local
- global
- static
- parameter
Local Scope
A variable
declared within a PHP function is local and can only be
accessed within
that function.
(the variable has local scope):
<?php
$a = 5; // global scope
function myTest()
{
echo $a; // local scope
}
myTest();
?>
?>
The
script above will not produce any output because the echo statement refers to
the local scope variable $a,
which has not been assigned a value within this scope.You can
have local variables with the same name in different functions because local
variables are only recognized by the function in which they are declared. Local
variables are deleted as soon as the function is completed.
Global Scope
Global
scope refers to any variable that is defined outside of any function.
Global
variables can be accessed from any part of the script that is not inside a
function.
To
access a global variable from within a function, use the global keyword:
<?php
$a = 5;
$b = 10;
function myTest()
{
global $a, $b;
$b = $a + $b;
}
myTest();
echo $b;
?>
$a = 5;
$b = 10;
function myTest()
{
global $a, $b;
$b = $a + $b;
}
myTest();
echo $b;
?>
The
script above will output 15.
PHP also
stores all global variables in an array called $GLOBALS[index]. Its
index is
the name
of the variable. This array is also accessible from within functions and
can
be used
to update global variables directly.
The
example above can be rewritten as this:
<?php
$a = 5;
$b = 10;
function myTest()
{
$GLOBALS['b'] = $GLOBALS['a'] + $GLOBALS['b'];
}
myTest();
echo $b;
?>
$a = 5;
$b = 10;
function myTest()
{
$GLOBALS['b'] = $GLOBALS['a'] + $GLOBALS['b'];
}
myTest();
echo $b;
?>
Static Scope
When a function is completed, all of its variables are normally deleted.
However,
sometimes you want a local variable to not be deleted.
To do this,
use the static the keyword when you first declare the variable:
static
$rememberMe;
Then, each
time the function is called, that variable will still have the
information
it contained
from the last time, the function was called.
Note: The
variable is still local to the function.
Parameters
A parameter is
a local variable whose value is passed to the function by the calling code.
Parameters are
declared in a parameter list as part of the function declaration:
function myTest($para1,$para2,...)
{
// function code
}
{
// function code
}
Parameters are
also called arguments. We will discuss them in more detail when we
talk about
functions.
PHP String Variables
String Variables in PHP
String
variables are used for values that contain characters.
In this blog
post, 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;
?>
$txt="Hello World";
echo $txt;
?>
Creating your first PHP Applications
Below, we have an
example of a simple PHP script that sends the text "Hello World" back
to the browser:
<html>
<body>
<?php
echo "Hello World";
?>
<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".
In the example above we have used the echo statement to output the text "Hello World".
Hello, my name is Jack Sparrow. I'm a 50 year old self-employed Pirate from the Caribbean.
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