PHP: Basics of PHP

Chapter one: Four Basics of PHP

₴ Introduction to PHP

₴ How to Run PHP File on XAMPP Server

₴ PHP Variables

₴ PHP Data Types

₴ PHP Operators

₴ Conditional Statements

₴ PHP Arrays

₴ PHP Looping

₴ PHP Functions

PHP is a server-side scripting language
Server side script language is a technique used in web development which involves employing script on a web server which produce a response customized for each users clients requests to the web site

What is PHP?

PHP stands for PHP: Hypertext Preprocessor
PHP scripts are executed on the server
PHP supports many databases (MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc...)
For our study we are focus on XAMPP server (includes Apache and MYSQL)
PHP is an open source software
PHP is free to download and use

What is a PHP File?

PHP files can contain text, HTML tags and scripts
PHP files are returned to the browser as plain HTML
PHP files have a file extension of ".php", ".php3", or ".phtml" but the first extension is the

common one

What is MySQL?

MySQL is a database server
MySQL is ideal for both small and large applications
MySQL supports standard SQL
MySQL compiles on a number of platforms
MySQL is free to download and use

PHP + MySQL

PHP combined with MySQL are cross-platform (you can develop in Windows

and serve on a Unix platform)

Why PHP?

PHP runs on different platforms (Windows, Linux, Unix, etc.)
PHP is compatible with almost all servers used today (Apache, IIS, etc...)
PHP is FREE to download from the official PHP resource: http://www.php.net
PHP is easy to learn and runs efficiently on the server side

PHP Syntax

PHP code is executed on the server, and the plain HTML result is sent to the

browser

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, I recommend that you use the standard form

(<?php) rather than the shorthand form

A PHP file normally contains HTML tags, just like an HTML file, and some PHP

scripting code

Next, I have an example of a simple PHP script which sends the text “Dear

Students, I am ready to do PHP Wares! If you are ready" to the browser:

PHP Syntax...

<html>

<body>

<?php

echo “Dear Students, I am ready to do PHP Wares! If you are ready…”;

</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 " Dear Students, I am ready to do PHP Wares! If you are ready " 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

Example:

<?php

// This is a single line comment

This is

a multiple line comment

How to run PHP file on XAMPP Server?

Step 1: Install XAMPP on your System
Step 2: Start Apache and MYSQL from XAMPP
Step 3: Open any text editor (Notepad++ or other)
Step 4: Write php program or code on the text editor
Step 5: Save the file in the c://xampp/htdocs directory after you created

a new folder

Step 6: Now, in your browser address bar, type the address:

http:/localhost/folder_name/filename.php

Example: localhost/exercises/exe1.php
Step 7: If you are correctly follow the steps the result easily displayed on the browser

PHP Variables

A variable is used to store information

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;

Example:

<?php

$txt=“My Water";

$x=3;

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 like JAVA and C++, 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, 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)

PHP Data Types

Variables can store data of different types, and different data types can do

different things

PHP supports the following data types:

üString

üInteger

üFloat (Floating point numbers - also called Double)

üBoolean (true or false, 0 or 1, ON or OFF, High V or Low V)

üArray

üNULL

PHP String

A string is a sequence of characters, like “My Water!"
A string can be any text inside quotes
You can use single or double quotes

Example:

<?php

$x = “My Water”;

$y = ‘My Water’; echo $x;

echo "<br>";

echo $y;

PHP Integer

An integer data type is a non-decimal number between -2,147,483,648 and

2,147,483,647

Rules for Integers:

An integer must have at least one digit
An integer must not have a decimal point
An integer can be either positive or negative
Integers can be specified in three formats: decimal (10-based), hexadecimal (16-based ) or octal (8-based)
The PHP var_dump() function returns the data type and value
In the following example $x is an integer

Example:

<?php

$x = 21;

var_dump($x);

PHP Boolean

A Boolean represents two possible states: TRUE or FALSE

$x = true;

$y = false;

Booleans are often used in conditional testing.

PHP Array

An array stores multiple values in one single variable
The position of array elements starts from 0 not 1
In the following example $movies is an array:

Example:

<?php

$movies= array(“Frozen",“Everything",“Baby Boss");

var_dump($movies);

echo $movies[0];

PHP NULL Value

Null is a special data type which can have only one value: NULL
A variable of data type NULL is a variable that has no value assigned to it

Tip: If a variable is created without a value, it is automatically assigned a value of NULL

Variables can also be emptied by setting the value to NULL:
Example:

<?php

$x = “My Water!";

$x = null;

var_dump($x);

PHP Strings

A string is a sequence of characters, like "Hello Water!"

Get The Length of a String

The PHP strlen() function returns the length of a string
The example below returns the length of the string "Hello Water!":

<?php

echo strlen("Hello Water!"); // Output: 12

Count The Number of Words in a String

The PHP str_word_count() function counts the number of words in a string

<?php

echo str_word_count("Hello Water!"); // Output: 2

Reverse a String

The PHP strrev() function reverses a string

Example:

<?php

echo strrev("Hello Water!"); // Outputs !retaW olleH

Search For a Specific Text Within a String

The PHP strpos() function searches for a specific text within a string
If a match is found, the function returns the character position of the first match. If no match is found,

it will return NULL

The example below searches for the text “Water" in the string "Hello Water!":

<?php

echo strpos("Hello World!", “Water"); // Output: 6

Tip: The first character position in a string is 0 (not 1)

Replace Text Within a String

The PHP str_replace() function replaces some characters with some other characters in a string
The example below replaces the text “Water" with “Sweety":

Example:

<?php

echo str_replace(“Water", “Sweety", "Hello Water!"); // Output: Hello Sweety!

The Concatenation Operator

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

(.)

Example:

<?php

$txt1=“I’m Author!”;

$txt2=“for You!"; echo $txt1 . " " . $txt2;

PHP Constants

Constants are like variables except that once they are defined they cannot be

changed or undefined

A constant is an identifier (name) for a simple value
The value cannot be changed during the script
A valid constant name starts with a letter or underscore
No $ sign before the constant name

Note: Unlike variables, constants are automatically global across the entire script

Create a PHP Constant

To create a constant, use the define() function

PHP Constants…

define(Name, Value, case-insensitive)

Parameters:

Name: Specifies the name of the constant
- Value: Specifies the value of the constant
- Case-insensitive: Specifies whether the constant
insensitive. Default is false
Example:
<?php
define("GREETING", “Hello Dear!");
echo GREETING;
?>
PHP Constants…

Example

<?php

define("GREETING", “Hello Dear", true);

echo greeting; // case insensitive

Constants are Global

Example

<?php

define("GREETING", “Hello Dear", true);

echo greeting; // case insensitive

Constants are Global

Constants are automatically global and can be used across the entire script
The example below uses a constant inside a function, even if it is defined outside the function:

<?php

define("GREETING", “Hello Dear");

function water()

{

echo GREETING;

}

watert();

PHP Operators

Operators are used to operate on values

PHP Operators

This section lists the different operators used in PHP

Arithmetic Operators

Conditional Statements

Conditional statements are used to perform different actions based on different

conditions

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:

<?php

$d=date("D");

if ($d=="Fri") { echo "Have a Nice Weekend!"; }

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

The if…else Statement

Syntax:

if (condition)

{

code to be executed if condition is true;

}

else

{

code to be executed if condition is false;

}

The if…else Statement…

Example:

The following example will output "Have a Nice Weekend!" if the current day is Friday, otherwise it will output "Have a Nice Day!":
<?php

$d = date("D");

if($d == "Fri") {

echo "Have a Nice Weekend!"; }

else {

echo "Have a Nice Day!"; }

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

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

to be executed

Syntax:

if (condition)

code to be executed if condition is true;

else if (condition)

code to be executed if condition is true;

else

code to be executed if condition is false;

The if...else if....else Statement…

Example:

The following example will output "Have a Nice Weekend!" if the current day is Friday, and "Have a Nice Monday!" if the current day is Monday. Otherwise it will output "Have a Nice day!"
<?php

$d = date("D");

if ($d == "Fri") {

echo “Have a Nice Weekend!"; } else if ("mon") {

echo “Have a Nice Monday"; }

else {

echo "Have a Nice Day!"; }

PHP Switch Statement

Use the switch statement to select one of many blocks of code to be executed

Syntax:

switch (n)

{

case label1:

code to be executed if n=label1;

break; case label2:

code to be executed if n=label2;

……………….

break;

default:

code to be executed if n is different from both label1 and label2;

}

PHP Switch Statement…

This is how it works: first we have a single expression n (most often a

variable), that is evaluated once

The value of the expression is then compared with the values for each

case in the structure

If there is a match, the block of code associated with that case is executed
Use break to prevent the code from running into the next case automatically
The default statement is used if no match is found

PHP Switch Statement…

Example:

<?php

$today = date("D"); switch($today){ case "Mon":

echo "Today is Monday";

break;

case "Tue":

echo "Today is Tuesday"; break;

case "Wed":

echo "Today is Wednesday";

PHP Switch Statement…

Example

break;

case "Thu":

echo "Today is Thursday";

break;

case "Fri":

echo "Today is Friday"; break;

case "Sat":

echo "Today is Saturday";

break;

case "Sun":

echo "Today is Sunday"; break;

echo "No information available for that day";

break;

}

PHP Arrays

An array stores multiple values in one single variable

What is an Array?

A variable is a storage area holding a number or text. The problem is, a variable will hold only one value
An array is a special variable, which can store multiple values in one single variable
If you have a list of items (a list of movies, for example), storing the movies in single variables could look like this:
$movies1=“Love Rain";

$movies2=“Everything";

$movies3=“Frozen";

However, what if you want to loop through the movies and find a specific

one? And what if you had not 3 movies, but 300?

PHP Arrays…

The best solution here is to use an array!
An array can hold all your variable values under a single name. And you

can access the values by referring to the array name

Each element in the array has its own index so that it can be easily

accessed

In PHP, there are three kind of arrays:

Numeric Array - An array with a numeric index
Associative Array - An array where each ID key is associated with a value
Multidimensional Array - An array containing one or more arrays

PHP Arrays…

Numeric Arrays

A numeric array stores each array element with a numeric index
There are two methods to create a numeric array

1.In the following example the index are automatically assigned (the

index starts at 0):

$life=array(“Live",“Dead",“Love",“Hate");

2.In the following example we assign the index manually:

$life[0]=“Live";

$life[1]=“Dead";

$life[2]=“Love";

$life[3]=“Hate";

PHP Arrays…

Example:

In the following example you access the variable values by referring to the array name and index:

<?php

$life[0]=“Live";

$life[1]=“Dead";

$life[2]=“Love";

$life[3]=“Hate";

echo $life[0] . " and " . $life[1] . " are common for us.";

The code above will output: Live and Dead are common for us.

PHP Arrays…

Associative Arrays

An associative array, each ID key is associated with a value
When storing data about specific named values, a numerical array is not

always the best way to do it

With associative arrays we can use the values as keys and assign values to them

Example:

In this example we use an array to assign ages to the different persons:

$ages = array("Water"=>21, « Steve"=>30, « Love"=>51);

PHP Arrays…

Example:

This example is the same as the previous one, but shows a different way of creating the array:
$ages[‘Water'] = "21";

$ages[‘Steve'] = "30";

$ages[‘Love'] = "34";

The ID keys can be used in a script:

<?php

$ages[‘Water'] = "21";

$ages[‘Steve'] = "30";

$ages[‘Love'] = "34";

echo “Water is " . $ages[‘Water'] . " years old.";

The code above will output: Water is 21 years old.

PHP Sorting Arrays

The elements in an array can be sorted in alphabetical or numerical order, descending or ascending

PHP - Sort Functions For Arrays

In this chapter, we will go through the following PHP array sort functions:

sort() - sort arrays in ascending order
rsort() - sort arrays in descending order
asort() - sort associative arrays in ascending order, according to the value
ksort() - sort associative arrays in ascending order, according to the key
arsort() - sort associative arrays in descending order, according to the value
krsort() - sort associative arrays in descending order, according to the key

Sort Array in Ascending Order - sort()

The following example sorts the elements of the $life array in ascending alphabetical order:

PHP: Basics of PHP

Post a Comment

Responsive Blog Website using PHP & MySQL Free Source Code Download

Categories

Main Tags

Latest Posts

Popular Posts

Responsive Blog Website using PHP & MySQL Free Source Code Download

Computer and Mobile Repair Shop Management System in PHP and Mysql

Shop Cosmetic and Beauty Products in PHP My SQL with Free Source code

Contact Form