Basic of PHP

Course Instructor: Nisa Soomro

 PHP and MySQL Web Development Fourth Edition “Luke Welling, Laura Thomson”
 http://sage.math.washington.edu/home/wstein/www/home/agc/lit/php/PHPMySQL.pdf
 www.W3school.com
2

PHP Intro
PHP Install
PHP Syntax
PHP Variables
PHP Echo / Print
PHP Data Types
PHP Constants
PHP Operators
PHP If...Else...Elseif
PHP Switch
PHP While Loops
PHP For Loops
3

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 costs nothing, it is free to download and use
4

 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"
5

<?php
echo "<h1 align='center'>Welcome to PHP </h1>";
?>
Execute this code and check the “View page source” you will find simple
following code
<h1 align='center'>Welcome to PHP </h1>
6

 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 restrict users to access some pages on your website
 PHP can encrypt data
With PHP you are not limited to output HTML. You can output images,
PDF files, and even Flash movies. You can also output any text, such as
XHTML and XML.
7

 PHP runs on various platforms (Windows, Linux, Unix, Mac OS X, etc.)
 PHP is compatible with almost all servers used today (Apache, IIS, etc.)
 PHP supports a wide range of databases
 PHP is free. Download it from the official PHP resource: www.php.net
 PHP is easy to learn and runs efficiently on the server side
8

The most universally effective PHP tag style is:
<?php
// Php Code here
?>
If you use this style, you can be positive that your tags will always be
correctly interpreted.
9

HTML script tags:
<script language=“php”>
// php code here
</script>
10

Short or short-open tags look like this:
<?
// Php Code here
?>
Set the short_open_tag setting in your php.ini file to on. This option must
be disabled to parse XML with PHP because the same syntax is used for
XML tags.
11

ASP-style tags:
ASP-style tags mimic the tags used by Active Server Pages to delineate
code blocks. ASP-style tags look like this:
<%
// php code here
%>
To use ASP-style tags, you will need to set the configuration option in
your php.ini file.
12

 A comment in PHP code is a line that is not read/executed as part of the
program. Its only purpose is to be read by someone who is editing the
code!
Comments are useful for:
 To let others understand what you are doing - Comments let other
programmers understand what you were doing in each step (if you work
in a group)
 To remind yourself what you did - Most programmers have experienced
coming back to their own work a year or two later and having to re-figure
out what they did. Comments can remind you of what you were thinking
when you wrote the code
13

PHP supports two types of comments
 Single line comment
// This is a single line comment
# This is also a single line comment
 Multiline comment
/* this is multiline comment
this is multiline comment
*/
14

 In PHP, all user-defined functions, classes, and keywords (e.g. if, else,
while, echo, etc.) are NOT case-sensitive.
 In the example below, all three echo statements below are legal (and
equal):
<?php
ECHO "Hello World!<br>";
echo "Hello World!<br>";
EcHo "Hello World!<br>";
?>
15

 However; in PHP, all variables are case-sensitive.
 In the example below, only the first statement will display the value of
the $color variable (this is because $color, $COLOR, and $coLOR are
treated as three different variables):
<?php
$color="red";
echo "My car is " . $color . "<br>";
echo "My house is " . $COLOR . "<br>";
echo "My boat is " . $coLOR . "<br>";
?>
16

 Whitespace is the stuff you type that is typically invisible on the screen,
including spaces, tabs, and carriage returns (end-of-line characters).
 PHP whitespace insensitive means that it almost never matters how
many whitespace characters you have in a row.
 one whitespace character is the same as many such characters
 For example, each of the following PHP statements that assigns the
sum of 2 + 2 to the variable $four is equivalent:
17

$four = 2 + 2; // single spaces
$four = 2 + 2 ; // spaces and tabs
$four =
2+
2; // multiple lines
All are same. It doesn’t matter how many spaces your are providing in a
statement, it will be considered as a single space.
18

 Variables are "containers" for storing information
 PHP variables can be used to hold values (x=5) or expressions (z=x+y).
 A variable can have a short name (like x and y) or a more descriptive name (age, carname,
total_volume).
Rules for PHP variables:
 A variable starts with the $ sign, followed by the name of the variable
 A variable name must start with a letter or the underscore character
 A variable name cannot start with a number
 A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
 Variable names are case sensitive ($y and $Y are two different variables)
19

 All variables in PHP are denoted with a leading dollar sign ($).
 The value of a variable is the value of its most recent assignment.
 Variables are assigned with the = operator, with the variable on the left-hand side
and the expression to be evaluated on the right.
 Variables can, but do not need, to be declared before assignment.
 Variables in PHP do not have intrinsic types - a variable does not know in advance
whether it will be used to store a number or a string of characters.
 Variables used before they are assigned have default values.
 PHP does a good job of automatically converting types from one to another when
necessary.
 PHP variables are Perl-like.
20

 PHP has no command for declaring a variable.
 A variable is created the moment you first assign a value to it:
<?php
$txt="Hello world!";
$x=5;
$y=10.5;
?>
After the execution of the statements above, the variable txt will hold the
value Hello world!, the variable x will hold the value 5, and the
variable y will hold the value 10.5.
 Note: When you assign a text value to a variable, put quotes around
the value. 21

 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 other languages such as C, C++, and Java, the programmer must
declare the name and type of the variable before using it.
22

In PHP there is two basic ways to get output: echo and print.
There are some differences between echo and print:
 echo - can output one or more strings
 print - can only output one string, and returns always 1
Tip: echo is marginally faster compared to print as echo does not return any value.
23

 echo is a language construct, and can be used with or without parentheses: echo or
echo().
Display Strings
 The following example shows how to display different strings with the echo
command (also notice that the strings can contain HTML markup):
<?php
echo "<h2>PHP is fun!</h2>";
echo "Hello world!<br>";
echo "I'm about to learn PHP!<br>";
echo "This", " string", " was", " made", " with multiple parameters.";
?>
24

Display Variables
 The following example shows how to display strings and variables with
the echo command:
 <?php
$txt1="Learn PHP";
$txt2="W3Schools.com";
$cars=array("Volvo","BMW","Toyota");
echo $txt1;
echo "<br>";
echo "Study PHP at $txt2";
echo "<br>";
echo "My car is a {$cars[0]}";
?> 25

 print is also a language construct, and can be used with or without parentheses: print
or print().
Display Strings
 The following example shows how to display different strings with the print command
(also notice that the strings can contain HTML markup):
<?php
print "<h2>PHP is fun!</h2>";
print "Hello world!<br>";
print "I'm about to learn PHP!";
?>
26

Display Variables
 The following example shows how to display strings and variables with the print
command:
<?php
$txt1="Learn PHP";
$txt2="W3Schools.com";
print $txt1;
print "<br>";
print "Study PHP at $txt2";
print "<br>";
print "My car is a {$cars[0]}";
?>
27

Scope can be defined as the range of availability a variable has to the
program in which it is declared. PHP variables can be one of four scope
types:
 Local variables
 Function parameters
 Global variables
 Static variables
28

 A variable declared in a function is considered local; that is, it can be
referenced solely in that function. Any assignment outside of that
function will be considered to be an entirely different variable from the
one contained in the function:
29

<?
$x = 4;
function assignx () {
$x = 0;
print "$x inside function is $x. ";
}
assignx();
print "$x outside of function is $x. ";
?>
30

 In contrast to local variables, a global variable can be accessed in any
part of the program. However, in order to be modified, a global variable
must be explicitly declared to be global in the function in which it is to
be modified. This is accomplished, conveniently enough, by placing the
keyword GLOBAL in front of the variable that should be recognized as
global. Placing this keyword in front of an already existing variable tells
PHP to use the variable having that name. Consider an example:
31

<?
$somevar = 15;
function addit() {
GLOBAL $somevar;
$somevar++;
print "Somevar is $somevar";
}
addit();
?>
32

 The final type of variable scoping that I discuss is known as static. In
contrast to the variables declared as function parameters, which are
destroyed on the function's exit, a static variable will not lose its value
when the function exits and will still hold that value should the function
be called again.
 You can declare a variable to be static simply by placing the keyword
STATIC in front of the variable name.
33

<?
function keep_track() {
STATIC $count = 0;
$count++;
print $count;
print “ ";
}
keep_track();
keep_track();
keep_track();
?>
34

 Function parameters are declared after the function name and inside
parentheses. They are declared much like a typical variable would be:
<?
// multiply a value by 10 and return it to the caller
function multiply ($value) {
$value = $value * 10;
return $value;
}
$retval = multiply (10);
Print "Return value is $retvaln";
?> 35

PHP has a total of eight data types which we use to construct our variables:
1. Integers: are whole numbers, without a decimal point, like 4195.
2. Doubles: are floating-point numbers, like 3.14159 or 49.1.
3. Booleans: have only two possible values either true or false.
4. NULL: is a special type that only has one value: NULL.
5. Strings: are sequences of characters, like 'PHP supports string operations.'
6. Arrays: are named and indexed collections of other values.
7. Objects: are instances of programmer-defined classes, which can package up both other kinds of values and
functions that are specific to the class.
8. Resources: are special variables that hold references to resources external to PHP (such as database
connections).
The first five are simple types, and the next two (arrays and objects) are compound - the compound types can
package up other arbitrary values of arbitrary type, whereas the simple types cannot.
36

 They are whole numbers, without a decimal point, like 4195. They are the simplest type
.they correspond to simple whole numbers, both positive and negative. Integers can be
assigned to variables, or they can be used in expressions, like so:
$int_var = 12345;
$another_int = -12345 + 12345;
 Integer can be in decimal (base 10), octal (base 8), and hexadecimal (base 16) format.
Decimal format is the default, octal integers are specified with a leading 0, and hexadecimals
have a leading 0x.
37

They like 3.14159 or 49.1. By default, doubles print with the minimum number of
decimal places needed. For example, the code:
$many = 2.2888800;
$many_2 = 2.2111200;
$few = $many + $many_2;
print(.$many + $many_2 = $few<br>.);
It produces the following browser output:
2.28888 + 2.21112 = 4.5
38

Booleans can be either TRUE or FALSE.
$x=true;
$y=false;
Booleans are often used in conditional testing.
if (TRUE)
print("This will always print<br>");
else
print("This will never print<br>");
39

 NULL is a special type that only has one value: NULL. To give a variable the NULL
value, simply assign it like this:
$my_var = NULL;
 The special constant NULL is capitalized by convention, but actually it is case
insensitive; you could just as well have typed:
$my_var = null;
 A variable that has been assigned NULL has the following properties:
 It evaluates to FALSE in a Boolean context.
 It returns FALSE when tested with IsSet() function.
40

 A string is a sequence of characters, like "Hello world!".
 A string can be any text inside quotes. You can use single or double quotes:
<?php
$x = "Hello world!";
echo $x;
echo "<br>";
$x = 'Hello 12BS(CS)';
echo $x;
 ?>
41

<?
$variable = "name";
$literally = 'My $variable will not print!n';
print($literally);
$literally = "My $variable will print!n";
print($literally);
?>
42

 n is replaced by the newline character
 r is replaced by the carriage-return character
 t is replaced by the tab character
 $ is replaced by the dollar sign itself ($)
 " is replaced by a single double-quote (")
 is replaced by a single backslash ()
43

 An array stores multiple values in one single variable.
In the following example we create an array.
<?php
echo $car[0];
echo $car[1];
echo $car[2];
?>
44

 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.
45

 To set a constant, use the define() function - it takes three parameters:
1. The first parameter defines the name of the constant,
2. the second parameter defines the value of the constant,
3. the optional third parameter specifies whether the constant name
should be case-insensitive. Default is false.
46

The example below creates a case-sensitive constant, with the value of
"Welcome to W3Schools.com!":
<?php
define("GREETING", "Welcome to W3Schools.com!");
echo GREETING;
?>
The example below creates a case-insensitive constant, with the value of
"Welcome to W3Schools.com!":
<?php
define("GREETING", "Welcome to W3Schools.com!", true);
echo greeting;
?>
47

There is no need to write a dollar sign ($) before a constant,
where as in Variable one has to write a dollar sign.
Constants cannot be defined by simple assignment, they
may only be defined using the define() function.
Constants may be defined and accessed anywhere without
regard to variable scoping rules.
Once the Constants have been set, may not be redefined or
undefined.
48

PHP Arithmetic Operators
50
Operator Name Example Result
+ Addition $x + $y Sum of $x and $y
- Subtraction $x - $y Difference of $x and $y
* Multiplication $x * $y Product of $x and $y
/ Division $x / $y Quotient of $x and $y
% Modulus $x % $y Remainder of $x divided by $y

<?php
$x=10;
$y=6;
echo ($x + $y); // outputs 16
echo ($x - $y); // outputs 4
echo ($x * $y); // outputs 60
echo ($x / $y); // outputs 1.6666666666667
echo ($x % $y); // outputs 4
?>
51

 The PHP assignment operators is used to write a value to a variable.
 The basic assignment operator in PHP is "=". It means that the left
operand gets set to the value of the assignment expression on the right.
52
Assignment Same as... Description
x = y x = y The left operand gets set to the value of the expression on the
right
x += y x = x + y Addition
x -= y x = x - y Subtraction
x *= y x = x * y Multiplication
x /= y x = x / y Division
x %= y x = x % y Modulus

 <?php
$x=10;
echo $x; // outputs 10
$y=20;
$y += 100;
echo $y; // outputs 120
$z=50;
$z -= 25;
echo $z; // outputs 25
 $i=5;
$i *= 6;
echo $i; // outputs 30
$j=10;
$j /= 5;
echo $j; // outputs 2
$k=15;
$k %= 4;
echo $k; // outputs 3
?>
53

. Concatenation $txt1 = "Hello"
$txt2 = $txt1 . " world!"
Now $txt2 contains "Hello
world!"
.= Concatenation
assignment
$txt1 = "Hello"
$txt1 .= " world!"
Now $txt1 contains "Hello
world!"
54

55
<?php
$a = "Hello";
$b = $a . " world!";
echo $b; // outputs Hello world!
$x="Hello";
$x .= " world!";
echo $x; // outputs Hello world!
?>

Operator Name Description
++$x Pre-increment Increments $x by one, then returns $x
$x++ Post-increment Returns $x, then increments $x by one
--$x Pre-decrement Decrements $x by one, then returns $x
$x-- Post-decrement Returns $x, then decrements $x by one
56

57
<?php
$x=10;
echo ++$x; // outputs 11
$y=10;
echo $y++; // outputs 10
$z=5;
echo --$z; // outputs 4
$i=5;
echo $i--; // outputs 5
?>

 The PHP comparison operators are used to compare two values (number or string):
58
== Equal $x == $y True if $x is equal to $y
=== Identical $x === $y True if $x is equal to $y, and they are of the
same type
!= Not equal $x != $y True if $x is not equal to $y
<> Not equal $x <> $y True if $x is not equal to $y
!== Not identical $x !== $y True if $x is not equal to $y, or they are not of
the same type
> Greater than $x > $y True if $x is greater than $y
< Less than $x < $y True if $x is less than $y
>= Greater than or equal to $x >= $y True if $x is greater than or equal to $y
<= Less than or equal to $x <= $y True if $x is less than or equal to $y

and And $x and $y True if both $x and $y are true
or Or $x or $y True if either $x or $y is true
xor Xor $x xor $y True if either $x or $y is true, but not both
&& And $x && $y True if both $x and $y are true
|| Or $x || $y True if either $x or $y is true
! Not !$x True if $x is not true
59

 The PHP array operators are used to compare arrays:
60
+ Union $x + $y Union of $x and $y (but duplicate keys are
not overwritten)
== Equality $x == $y True if $x and $y have the same key/value
pairs
=== Identity $x === $y True if $x and $y have the same key/value
pairs in the same order and of the same
types
!= Inequality $x != $y True if $x is not equal to $y
<> Inequality $x <> $y True if $x is not equal to $y
!== Non-identity $x !== $y True if $x is not identical to $y

 Conditional statements are used to perform different actions based on different
conditions.
 Very often when you write code, you want to perform different actions for different
decisions. You can use conditional statements in your code to do this.
In PHP we have the following conditional statements:
1. if statement - executes some code only if a specified condition is true
2. if...else statement - executes some code if a condition is true and another code if
the condition is false
3. if...elseif....else statement - selects one of several blocks of code to be executed
4. switch statement - selects one of many blocks of code to be executed
61

The if statement is used to execute some code only if a specified condition is true.
 Syntax
if (condition)
{
code to be executed if condition is true;
}
<?php
$t=date("H");
if ($t<"20")
{
echo "Have a good day!";
}
?>
62

Use the if....else statement to execute some code if a condition is true and another
code if the condition is false.
Syntax
if (condition)
{
}
else
{
code to be executed if condition is false;
}
63

<?php
$t=date("H");
if ($t<"20")
{
}
else
{
echo "Have a good night!";
}
?>
64

Use the if....elseif...else statement to select one of several blocks of code to be
executed.
Syntax
if (condition)
{
}
elseif (condition)
{
}
else
{
code to be executed if condition is false;
}
65

<?php
$t=date("H");
if ($t<"10")
{
echo "Have a good
morning!";
}
elseif ($t<"20")
{
}
else
{
echo "Have a good night!";
}
?>
66

 The switch statement is used to perform different actions based on
different conditions.
 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;
...
default: code to be executed if n is different from all labels;
} 67

 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.
68

<?php
$d=date("D");
switch ($d)
{
case "Mon": echo "Today is Monday"; break;
case "Tue": echo "Today is Tuesday"; break;
case "Wed": echo "Today is Wednesday"; 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;
default: echo "Wonder which day is this ?";
}
?> 69

Often when you write code, you want the same block of code to run over
and over again in a row. Instead of adding several almost equal code-lines in
a script, we can use loops to perform a task like this.
In PHP, we have the following looping statements:
1.while - loops through a block of code as long as the specified condition
is true
2.do...while - loops through a block of code once, and then repeats the
loop as long as the specified condition is true
3.for - loops through a block of code a specified number of times
4.foreach - loops through a block of code for each element in an array
70

The while loop executes a block of code as long as the specified
condition is true.
Syntax
while (condition is true)
{
code to be executed;
}
71

The example below first sets a variable $x to 1 ($x=1;). Then, the while
loop will continue to run as long as $x is less than, or equal to 5. $x will
increase by 1 each time the loop runs ($x++;):
Example
<?php
$x=1;
while($x<=5)
{
echo "The number is: $x <br>";
$x++;
}
?>
72

The do...while loop will always execute the block of code once, it will
then check the condition, and repeat the loop while the specified
condition is true.
Syntax
do
{
}
while (condition is true);
73

The example below first sets a variable $x to 1 ($x=1;). Then, the do while
loop will write some output, and then increment the variable $x with 1. Then
the condition is checked (is $x less than, or equal to 5?), and the loop will
continue to run as long as $x is less than, or equal to 5:
Example
<?php
$x=1;
do
{
$x++;
}
while ($x<=5)
?>
74

 Notice that in a do while loop the condition is tested AFTER executing the
statements within the loop. This means that the do while loop would execute its
statements at least once, even if the condition fails the first time.
 The example below sets the $x variable to 6, then it runs the loop, and then the
condition is checked:
<?php
$x=6;
do
{
$x++;
}
while ($x<=5)
?>
75

The for loop is used when you know in advance how many times the
script should run.
Syntax
for (init counter; test counter; increment counter)
{
}
76

Parameters:
 init counter: Initialize the loop counter value
 test counter: Evaluated for each loop iteration. If it evaluates to TRUE,
the loop continues. If it evaluates to FALSE, the loop ends.
 increment counter: Increases the loop counter value
77

The example below displays the numbers from 0 to 10:
Example
<?php
for ($x=0; $x<=10; $x++)
{
}
?>
78

The foreach loop works only on arrays, and is used to loop through each
key/value pair in an array.
Syntax
foreach ($array as $value)
{
}
For every loop iteration, the value of the current array element is assigned to
$value and the array pointer is moved by one, until it reaches the last array
element.
79

The following example demonstrates a loop that will output the values of the
given array ($colors):
Example
<?php
$colors = array("red","green","blue","yellow");
foreach ($colors as $value)
{
echo "$value <br>";
}
?>
80

 The PHP break keyword is used to terminate the execution of a loop
prematurely.
 The break statement is situated inside the statement block. If gives you
full control and whenever you want to exit from the loop you can come
out. After coming out of a loop immediate statement to the loop will be
executed.
81

 In the following example condition test becomes true when the counter value reaches 3
and loop terminates.
<?php
$i = 0;
while( $i < 10)
{
$i++;
if( $i == 3 )break;
}
echo ("Loop stopped at i = $i" );
?>
82

 The PHP continue keyword is used to halt the current iteration of a loop
but it does not terminate the loop.
 Just like the break statement the continue statement is situated inside
the statement block containing the code that the loop executes,
preceded by a conditional test. For the pass
encountering continue statement, rest of the loop code is skipped and
next pass starts.
83

Example
 In the following example loop prints the value of array but for which condition
becomes true it just skip the code and next value is printed.
<?php
$array = array( 1, 2, 3, 4, 5);
foreach( $array as $value )
{
if( $value == 3 )continue;
echo "Value is $value <br />";
}
?>
84

 The real power of PHP comes from its functions; it has more than 1000 built-in
functions.
PHP User Defined Functions
 Besides the built-in PHP functions, we can create our own functions.
 A function is a block of statements that can be used repeatedly in a program.
 A function will not execute immediately when a page loads.
 A function will be executed by a call to the function.

85

A user defined function declaration starts with the word "function":
Syntax
function functionName()
{
}
Note: A function name can start with a letter or underscore (not a
number).
Tip: Give the function a name that reflects what the function does!
86

 In the example below, we create a function named "writeMsg()". The
opening curly brace ( { ) indicates the beginning of the function code
and the closing curly brace ( } ) indicates the end of the function. The
function outputs "Hello world!". To call the function, just write its name:
<?php
function writeMsg()
{
echo "Hello world!";
}
writeMsg(); // call the function
?>
87

 Information can be passed to functions through arguments. An argument is just like a variable.
 Arguments are specified after the function name, inside the parentheses. You can add as many
arguments as you want, just seperate them with a comma.
<?php
function addFunction($num1, $num2)
{
$sum = $num1 + $num2;
echo "Sum of the two numbers is : $sum";
}
addFunction(10, 20);
?>
88

 A function can return a value using the return statement in conjunction
with a value or object. return stops the execution of the function and
sends the value back to the calling code.
 You can return more than one value from a function using return
array(1,2,3,4).
 Following example takes two integer parameters and add them
together and then returns their sum to the calling program. Note
that return keyword is used to return a value from a function.
89

<?php
function addFunction($num1, $num2)
{
$sum = $num1 + $num2;
return $sum;
}
$return_value = addFunction(10, 20);
echo "Returned value from the function : $return_value";
?>
90

<?php
function table($a = 12)
{
for($i=1; $i<10; $i++)
{
echo " $a * $i = $a*$i <br />" ;
}
}
table();
table(3);
?>
91

 It is possible to pass arguments to functions by reference. This means
that a reference to the variable is manipulated by the function rather
than a copy of the variable's value.
 Any changes made to an argument in these cases will change the
value of the original variable. You can pass an argument by reference
by adding an ampersand (&) to the variable name in either the function
call or the function definition.
92

<?php
function addFive($num)
{
$num += 5;
}
function addSix(&$num)
{
$num += 6;
}
$orignum = 10;
addFive($orignum );
echo "Original Value is $orignum<br />";
addSix( $orignum );
echo "Original Value is $orignum<br />";
?>
93

What is an Array?
 An array stores multiple values in one single variable:
 An array is a special variable, which can hold more than one value at a time.
 If you have a list of items (a list of car names, for example), storing the cars in single
variables could look like this:
$cars1="Volvo";
$cars2="BMW";
$cars3="Toyota";
 However, what if you want to loop through the cars and find a specific one? And what
if you had not 3 cars, but 300?
 The solution is to create an array!
94

 An array can hold many values under a single name, and you can access the values
by referring to an index number.
Create an Array in PHP
In PHP, the array() function is used to create an array:
 array();
In PHP, there are three types of arrays:
1.Indexed arrays - Arrays with numeric index
2.Associative arrays - Arrays with named keys
3.Multidimensional arrays - Arrays containing one or more arrays
95

There are two ways to create indexed arrays:
The index can be assigned automatically (index always starts at 0):
 or the index can be assigned manually:
$cars[0]="Volvo";
$cars[1]="BMW";
$cars[2]="Toyota";
96

 The following example creates an indexed array named $cars, assigns
three elements to it, and then prints a text containing the array values:
Example
 <?php
echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . ".";
?>
97

The count() function is used to return the length (the number
of elements) of an array:
Example
<?php
echo count($cars);
?>
98

To loop through and print all the values of an indexed array, you could
use a for loop, like this:
Example
<?php
$arrlength=count($cars);
for($x=0; $x<$arrlength; $x++)
{
echo $cars[$x];
echo "<br>";
}
?> 99

Associative arrays are arrays that use named keys that you assign to them.
There are two ways to create an associative array:
$age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43");
or:
$age['Peter']="35";
$age['Ben']="37";
$age['Joe']="43";
The named keys can then be used in a script:
Example
<?php
echo "Peter is " . $age['Peter'] . " years old.";
?>
100

Loop Through an Associative Array
 To loop through and print all the values of an associative array, you could use a
foreach loop, like this:
Example
 <?php
foreach($age as $x=>$x_value)
{
echo "Key=" . $x . ", Value=" . $x_value;
echo "<br>";
}
?>
101

 A multi-dimensional array 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. Values in the multi-dimensional
array are accessed using multiple index.
Example
 In this example we create a two dimensional array to store marks of three students in
three subjects:
 This example is an associative array, you can create numeric array in the same
fashion.
102

$marks = array(
"mohammad" => array
(
"physics" => 35,
"maths" => 30,
"chemistry" => 39
),
" Zara" => array
(
"physics" => 31,
"maths" => 22,
"chemistry" => 39
) );
103

/* Accessing multi-dimensional array values */
echo "Marks for mohammad in physics : " ;
echo $marks['mohammad']['physics'] . "<br />";
echo "Marks for zara in chemistry : " ;
echo $marks['zara']['chemistry'] . "<br />";
104

 http://www.w3schools.com/php/
 http://www.tutorialspoint.com/php/php_introduction.htm
105

Basic of PHP

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