Learn PHP Basics

PHP 5
"PHP: Hypertext Preprocessor“
Vipula Dissanayake
(HDCS/HND/C.E.H/MCSE)

What is PHP?
 PHP is an acronym for "PHP: Hypertext Preprocessor"
 PHP is a widely-used, open source scripting language
 PHP scripts are executed on the server
 PHP is free to download and use

What You Should Already Know
 Before you continue you should have a basic understanding of the following:
 HTML
 CSS
 JavaScript

What is a PHP File?
 PHP files can contain text, HTML, CSS, JavaScript, and PHP code
 PHP code are executed on the server, and the result is returned to the
browser as plain HTML
 PHP files have extension ".php"

What Can PHP Do?
 PHP can generate dynamic page content
 PHP can create, open, read, write, delete, and close files on the server
 PHP can collect form data
 PHP can send and receive cookies
 PHP can add, delete, modify data in your database
 PHP can be used to control user-access
 PHP can encrypt data

PHP script starts with?
<?php
// PHP code goes here
?>

Offline Servers
• WAMP stands for
Windows/Apache / MySQL / PHP
• LAMP stands for
Linux/Apache / MySQL / PHP

XAMPP
 XAMPP is a free and open source cross-platform web server package
 X (meaning cross-platform/ multi-platform)
 Apache
 MySQL
 PHP
 Perl
A platform is a combination of hardware and software used to run software
applications.

Syntax!
 A PHP scripting block always starts with
Syntax
<?php and ends with ?>
 A PHP scripting block can be placed anywhere in the document.

Saving File
Without
PHP
code
With
PHP
code
myfile.html
myfile.php
myfile.html
myfile.php




File name . extension

Comments
 // or # to make a single-line comment
 /* and */ to make a large comment block.
 <html><body>
<?php
// This is a comment
# This is a comment
/* This is a comment block */
?>
</body></html>

Data Types
 PHP supports eight primitive types.
 boolean
 integer
 float (floating-point number, 'double')
 string
 array
 object
 resource
 NULL

Variables
 Variables are used for storing values, such as numbers, strings or function
results, so that they can be used many times in a script.

Variable Naming Rules
 All variables in PHP start with a $ sign symbol. Variables may contain strings,
numbers, or arrays.
 A variable name must start with a letter or an underscore "_“
 A variable name can only contain alpha-numeric characters and underscores
(a-Z, 0-9, and _ )
 A variable name should not contain spaces.
e.g-($myString)

Naming Rules
 If a variable name should be more than one word, it should be separated with
underscore ($my_string)
 Keywords may not be used as variable name
 Variable names are Case-sensitive
Note: abc and ABC are distinct variable names

Assigning Values To Variables
 $x=10; // numeric values
 $y=“ABC”; or $y=‘ABC’; // string values
$x = 10;
Literals are any numbers ,text, or other information that directly represent a
value
Identifier Assign Sign Literal

Predefined variables
 PHP uses predefined variables to provide access to important information
about the server and requests from a browser.
 Since version 4.1.0 of PHP, the use of the new autoglobals, also known as
superglobals, have been the recommended way to access predefined
variables

Superglobals
 $_GLOBALS
 $_SERVER
 $_GET
 $_POST
 $_COOKIE
 $_FILES
 $_ENV
 $_REQUEST
 $_SESSION

Operators
 Operators are used to manipulate or perform operations on variables and
values

Arithmetic Operators
 As the name suggests PHP arithmetic operators provide a mechanism for
performing mathematical operations:

Operator Name Example Result
+ Addition $a + $b Sum of $a and $b.
- Subtraction $a - $b Difference of $a and $b.
* Multiplication $a * $b Product of $a and $b.
/ Division $a / $b Quotient of $a and $b.
% Modulus $a % $b Remainder of $a divided by $b.
++var Pre-increment ++$a Increments $a by one, then returns $a.
var++
Post-
increment
$a++ Returns $a, then increments $a by one.
--var
Pre-
decrement
--$a Decrements $a by one, then returns $a.
Var--
Post-
decrement
$a-- Returns $a, then decrements $a by one.

Increment and decrement operators
 Prefix operators if listed before variable name
 Prefix operator is incremented by 1 before the value is assign to new variable
 Postfix operators if listed after a variable name
 Postfix operators receives the value of old variable before it is incremented
by 1

Assignment Operators
 The assignment operator is used to assign a value to a variable and is
represented by the equals (=) sign.
 The assignment operator can also be combined with arithmetic operators to
combine an assignment with a mathematical operation (for example to
multiple one value by another and assigning the result to the variable).

Operator Name Example Is The Same As
= Assignment x=y x=y
+= Addition-Assignment x+=y x=x+y
-= Subtraction-Assignment x-=y x=x-y
*= Multiplication-Assignment x*=y x=x*y
/= Division-Assignment x/=y x=x/y
%= Modulo-Assignment x%=y x=x%y

Comparison Operators
 The comparison operators provide the ability to compare one value against
another and return either a true or false result depending on the status of
the match.
 The comparison operators are used with two operands, one to the left and
one to the right of the operator.
 If you compare an integer with a string, the string is converted to a number.
If you compare two numerical strings, they are compared as integers.

Operato
r
Name Example Result
== Equal $a == $b TRUE if $a is equal to $b.
=== Identical $a === $b
TRUE if $a is equal to $b, and they
are of the same type. (introduced in
PHP 4)
!= Not equal $a != $b TRUE if $a is not equal to $b.
<> Not equal $a <> $b TRUE if $a is not equal to $b.
!== Not identical $a !== $b
TRUE if $a is not equal to $b, or they
are not of the same type. (introduced
in PHP 4)
< Less than $a < $b TRUE if $a is strictly less than $b.
> Greater than $a > $b TRUE if $a is strictly greater than $b.
<= Less than or equal to $a <= $b TRUE if $a is less than or equal to $b.
>=
Greater than or equal
to
$a >= $b
TRUE if $a is greater than or equal to
$b.

Logical Operators
 Logical Operators are also known as Boolean Operators because they evaluate
parts of an expression and return a true or false value, allowing decisions to
be made about how a script should proceed.
 Logic operators can be used to combine two or more comparison statements
combined into one statement to determine its status.

Operator Name Example Result
! Not ! $a TRUE if $a is not TRUE.
&& And $a && $b
TRUE if both $a and $b are
TRUE.
|| Or $a || $b
TRUE if either $a or $b is
TRUE.

String Operators
 The PHP String concatenation operator is used to combine values to create a
string.
 The concatenation operator is represented by a period/full stop (.) and can
be used to build a string from other strings, variables containing non-strings
(such as numbers) and even constants:

String Operators
 There are two string operators.
 The first is the concatenation operator ('.'), which returns the concatenation
of its right and left arguments.
 The second is the concatenating assignment operator ('.='), which appends the
argument on the right side to the argument on the left side.

Ex
<?php
$a = "Hello ";
$b = $a . "World!"; // now $b contains "Hello
World!"
$a = "Hello ";
$a .= "World!"; // now $a contains "Hello
World!"
?>

Control Structures
 One of the main reasons for using scripting languages such as PHP is to build
logic and intelligence into the creation and deployment of web based data. In
order to be able to build logic into PHP based scripts, it is necessary for the
script to be able to make decisions and repeat tasks based on specified
criteria.

Control Structures
 These PHP structures can be broken down into a number of categories as
follows:
 Conditional Statements
 Switch Statements
 Looping Statements

Conditional Statements
 Conditional statements provide the core of building decision making into
scripting languages such as PHP. Conditional statements essentially control
whether a part of a script is executed depending the result of a particular
expression (i.e whether an expression returns a boolean true or false value).

 The PHP if Statement
Use this statement if you want to execute some code only if a specified
condition is true
Syntax
if (condition)
{ code to be executed if condition is true;}

If…else
 The PHP if ... else Statements
 The if statement above allows you to specify what should happen if a
particular expression evaluates to true. It does not, however, provide the
option to specify something else that should happen in the event that the
expression evaluates to be false
 If you want to execute some code if a condition is true and another code if a
condition is false, use the if....else statement.

If..else
 The PHP if ... else Statements
Syntax
if (condition)
else
{ code to be executed if condition is false;}

syntax
 The PHP if ... elseif…else… Statements
Use this statement if you want to select one of many blocks of code to be
executed
Syntax
if (condition 1)
elseif (condition 2)
{code to be executed if condition is true;}
elseif (condition 3)
else
{ code to be executed if condition is false;}

 Switch Statements
Use this statement if you want to select one of many blocks of code to be executed
Syntax
switch(expression){
case 1:
execute code block 1
break;
case 2:
execute code block 2
break;
default:
code to be executed if n is different from case 1 and 2
}

Looping Statements
 Loop statements are the primary mechanism for telling a computer to
perform the same task over and over again until a set of criteria are met
 Loops in PHP are used to execute the same block of code a specified number
of times or while a specified condition is true.

Looping Statements
 PHP for loops
The for statement is used when you know how many times you want to
execute a statement or a list of statements.
Syntax
for (initialization; condition; increment)
{ code to be executed;}

Multiple for loop
Syntax
for (initialization 1; condition 1; increment 1){
for (initialization 2; condition 2; increment 2){
code to be executed;
}
}

The while loop
 The while loop
The while statement will execute a block of code if and as long as a condition
is true.
Syntax
while (condition){
}

The do...while Statement
 The do...while Statement
The do...while statement will execute a block of code at least once - it then
will repeat the loop as long as a condition is true.
Syntax
do {
}
while (condition);

break statements
 break ends execution of the current for, foreach, while, do-while or switch
structure.
 break accepts an optional numeric argument which tells it how many nested
enclosing structures are to be broken out of.

continue statements
 continue is used within looping structures to skip the rest of the current loop
iteration and continue execution at the condition evaluation and then the
beginning of the next iteration.
 continue accepts an optional numeric argument which tells it how many
levels of enclosing loops it should skip to the end of.

return statements
 If called from within a function, the return() statement immediately ends
execution of the current function, and returns its argument as the value of
the function call. return() will also end the execution of an eval() statement
or script file.

require() & include()
 The require() statement includes and evaluates the specific file.
 require() includes and evaluates a specific file. Detailed information on how
this inclusion works is described in the documentation for include().
 include()
 The include() statement includes and evaluates the specified file.

PHP Arrays
 An array can store one or more values in a single variable name.
 PHP arrays allow you to store groups of related data in one variable (as
opposed to storing them in separate variables).
 If you want to create many similar variables, you can store the data as
elements in an array.
 Each element in the array has its own ID so that it can be easily accessed.

There are three different kind of arrays:
 Numeric array - An array with a numeric ID key
 Associative array - An array where each ID key is associated with a value
 Multidimensional array - An array containing one or more arrays

Numeric Arrays
 A numeric array stores each element with a numeric ID key.
 Can be assigned the ID key Manually or Automatically.
 Each value of the array get a unique ID which is known as INDEX NUMBER.
 Remember that the index number starts from 0.
 Assign the ID key Automatically.
Syntax
Variable = array(“elem1"," elem2"," elem3");
 element=KEY

Associative Arrays
 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.
 When we want to store elements in array with some meaningful association
other than numbers, we use associative array

Associative Arrays
 Syntax I
variable=array(“Ele1"=>value,“Ele2"=>value,“Ele3"=>value);
 Element names are case-sensitive, but type insensitive. It means that 'a'
differs from 'A' but '1' is the same as 1.

The foreach Statement
 The foreach statement is used to loop through arrays.
Syntax
foreach (array as value){
code to be executed ;
}

Multidimensional Arrays
 Each element in the main array can also be an array.
 And each element in the sub-array can be an array, and so on.
 A multidimensional array can contain arrays within itself and the sub arrays
contain more arrays within them

PHP Functions
 A function is a block of code that can be executed whenever we need it.
 A function is a named block of code that performs a specific task, possibly
acting upon a set of values given to it, or parameters , and possibly
returning a single value.

Functions
 Functions save on compile time—no matter how many times you call them,
functions are compiled only once for the page.
 They also improve reliability by allowing you to fix any bugs in one place,
rather than everywhere you perform a task, and they improve readability
by isolating code that performs specific tasks.
 Functions in a PHP program can be either built-in or user-defined.
 Regardless of their source, all functions are evaluated in the same way:

Create a PHP Function- user-defined
 All functions start with the word “function()”
 Name the function - It should be possible to understand what the function
does by its name. The name can start with a letter or underscore (not a
number)
 Add a "{" - The function code starts after the opening curly brace
 Insert the function code
 Add a "}" - The function is finished by a closing curly brace

Syntax
function Functionname() {
echo “Php Script";
}
// call the function
Functionname();

PHP Built-in Functions
PHP Array PHP Calendar PHP Date
PHP Error PHP Filter PHP FTP
PHP HTTP PHP Libxml PHP Mail
PHP Math PHP Misc PHPMySQL
PHP String PHP XML PHP Zip
PHP SimpleXML
PHP Filesystem
PHP Directory

Array Functions
 These functions allow you to interact with and manipulate arrays in various
ways. Arrays are essential for storing, managing, and operating on sets of
variables.

Syntax Of Array
array()
Syntax:
array(key => value)

array_count_values()
Counts all the values of an array
Syntax:
array_count_values ($input )

array_combine()
Creates an array by using one array for keys and another for its values
Syntax:
array_combine ($keys ,$values )

array_merge()
Merge one or more arrays
Syntax
array_merge ($array1 , $array2 , array $... )

array_product()
The array_product() function calculates and returns the product of an array.
Syntax:
array_product($array)

array_push()
Push one or more elements onto the end of array
Syntax
array_push ( $array , $var 1, $var2, $var... )

array_sum ()
Calculate the sum of values in an array
Syntax:
array_sum ($array )

Count()
Count elements in an array, or properties in an object
Syntax
count ($var )

array_unique()
Removes duplicate values from an array
Syntax
array_unique ( $array )

asort()
Sort an array and maintain index association
Syntax
asort ($array )

arsort()
Sort an array in reverse order and maintain index association
Syntax
arsort ($array )

ksort()
Sort an array by key
Syntax
ksort ($array )

krsort()
Sort an array by key in reverse order
Syntax
krsort ($array )

array_rand()
Pick one or more random entries out of an array
Syntax:
array_rand ( array $input [, int $num_req ] )
num_req Specifies how many entries you want to pick -if not specified, defaults
to 1.

Mathematical Functions
 These math functions will only handle values within the range of the integer
and float types on your computer

abs()
The abs() function returns the absolute value of a number.
Syntax:
abs (x)

ceil()
Returns the value of a number rounded UPWARDS to the nearest integer.
Syntax:
ceil (x)

floor()
Returns the value of a number rounded DOWNWARDS to the nearest integer.
Syntax:
floor(x)

max()
The max() function returns the number with the highest value of two
specified numbers.
Syntax:
max (x,y)

min()
The min() function returns the number with the smallest value of two
specified numbers.
Syntax:
min (x,y)

mt_rand()
Generate a better random value
Syntax
mt_rand ( int $min , int $max )

rand()
Generate a random integer
Syntax
rand ( int $min , int $max )

round()
Rounds a float
Syntax
round ($val ,$precision )

pow ()
The pow() function raises the first argument to the power of the second
argument, and returns the result.
Syntax:
pow (x,y)

sqrt()
The sqrt() function returns the square root of a number
Syntax:
sqrt(x)

Variable handling Functions
is_array()
Finds whether a variable is an array
Syntax
is_array ($var )

empty()
Determine whether a variable is empty
Syntax
empty ($var )

is_bool()
Finds out whether a variable is a boolean
Syntax
is_bool ($var )

is_float()
Finds whether the type of a variable is float
Syntax
is_float ($var )

is_int()
Find whether the type of a variable is integer
Syntax
is_int ($var )

is_numeric()
Finds whether a variable is a number or a numeric string
Syntax
is_numeric ($var )

is_string()
Find whether the type of a variable is string
Syntax
is_string ($var )

Isset()
Determine whether a variable is set
Syntax
isset ($var,$var ,$ var... )

unset()
Unset a given variable / destroys the specified variables
Syntax
unset ($var ,$var ,$var... )

var_dump()
This function displays structured information about one or more expressions that
includes its type and value
Syntax
var_dump ($expression ,$expression ,$... )

is_null()
Finds whether a variable is NULL
Syntax
is_null ($var )

String Functions
 The string functions allow you to manipulate strings.

strtoupper()
Make a string uppercase
Syntax
strtoupper ($string )

strtolower()
Make a string lowercase
Syntax
strtolower ($string )

ucwords()
Uppercase the first character of each word in a string
Syntax
ucwords ($str )

Strlen()
Get string length
Syntax
strlen ($string )

implode()
Join array elements with a string
Syntax
implode ($glue , $pieces )

explode()
Split a string by string
Syntax
explode ($delimiter , $string , $limit )

ltrim()
Strip whitespace (or other characters) from the beginning of a string
Syntax
ltrim ($str ,$charlist )

rtrim()
Strip whitespace (or other characters) from the end of a string
Syntax
rtrim ($str ,$charlist)

trim()
Strip whitespace (or other characters) from the beginning and end of a string
Syntax
trim ($str ,$charlist )

str_repeat()
Repeat a string
Syntax
str_repeat ($input , $multiplier )

str_replace()
Replace all occurrences of the search string with the replacement string
Syntax
str_replace ($search ,$replace , $subject ,$count )

str_split()
Convert a string to an array
Syntax
str_split ($string , $split_length)

str_word_count()
Return information about words used in a string
Syntax
str_word_count ($string ,$format , $charlist)

Strpos()
Find position of first occurrence of a string
Syntax
strpos ($haystack ,$needle ,$offset )

Miscellaneous Functions
sleep()
Delay execution
Syntax
sleep(seconds)

die() or exit()
Output a message and terminate the current script
Syntax
die($message )
Syntax
exit($message )

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