Transcript PHP

Outline
•
What is PHP?
•
History of PHP
•
Why PHP ?
•
What is PHP file?
•
What you need to start using PHP ?
•
Syntax PHP code .
•
echo & print Statement
•
Variables.
•
Data Types.
•
Constants &Operators.
•
Conditional Statements & Loops.
What is PHP?

Personal Homepage Tools/Form Interpreter

PHP is a Server-side Scripting Language designed specifically for the
Web.

An open source language

PHP code can be embedded within an HTML page, which will
be executed each time that page is visited.
What is PHP? (cont’d)
•
Interpreted language, scripts are parsed at run-time rather than
compiled beforehand
•
Executed on the server-side
•
Source-code not visible by client
•
‘View Source’ in browsers does not display the PHP code
•
Various built-in functions allow for fast development
•
Compatible with many popular databases
History of PHP

PHP (PHP: Hypertext Preprocessor) was created by Rasmus Lerdorf in 1994. It was initially developed for
HTTP usage logging and server-side form generation in Unix.

PHP 2 (1995) transformed the language into a Server-side embedded scripting language. Added database
support, file uploads, variables, arrays, recursive functions, conditionals, iteration, regular expressions, etc.

PHP 3 (1998) added support for ODBC data sources, multiple platform support, email protocols
(SNMP,IMAP), and new parser written by Zeev Suraski and Andi Gutmans .

PHP 4 (2000) became an independent component of the web server for added efficiency. The parser was
renamed the Zend Engine. Many security features were added.

PHP 5 (2004) adds Zend Engine II with object oriented programming, robust XML support using the libxml2
library, SOAP extension for interoperability with Web Services, SQLite has been bundled with PHP
Why PHP ?

PHP runs on different platforms (Windows, Linux, Unix, Mac OS X, etc.)

PHP is compatible with almost all servers used today (Apache, IIS, etc.)

PHP has support for 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
What does PHP code look like?
•
Structurally similar to C/C++
•
Supports procedural and object-oriented paradigm
(to some degree)
What Can PHP Do?

PHP can generate dynamic page content

PHP can create, open, read, write, 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
What is a PHP File?

PHP files can contain text, HTML, JavaScript code,
and PHP code

PHP code are executed on the server, and the result
is returned to the browser as plain HTML

PHP files have a default file extension of ".php”
What you need to start using PHP ?
Installation


You will need
1.
Web server ( Apache )
2.
PHP ( version 5.3)
3.
Database ( MySQL 5 )
4.
Text editor (Notepad)
5.
Web browser (Firefox )
6.
www.php.net/manual/ en/install.php
Syntax PHP code


A PHP script can be placed anywhere in the
document.
A PHP script starts with
<?php and ends with ?>
Syntax PHP code
•
Standard Style :
<?php …… ?>
•
Short Style:
<? … ?>
•
Script Style:
<SCRIPT LANGUAGE=‘php’> </SCRIPT>
•
ASP Style:
<% echo “Hello World!”; %>
Echo

The PHP command ‘echo’ is used to output the parameters
passed to it .

The typical usage for this is to send data to the client’s web-
browser

Syntax : void echo (string arg1 [, string argn...])

In practice, arguments are not passed in parentheses since
echo is a language construct rather than an actual function
Echo - Example

<?php
echo “ This my first statement in PHP language“;

?>
Print

print is not actually a real function (it is a language
construct) so you are not required to use parentheses
with its argument list.
<?php
print("Hello World");
?>
Echo Vs Print
Improve this chart
Parameters:
Echo
Print
echo can take more than one parameter when
print only takes one parameter.
used without parentheses. The syntax is echo
expression [, expression[, expression] ... ]. Note
that echo ($arg1,$arg2) is invalid.
Return value:
Syntax:
What is it?:
echo does not return any value
print always returns 1 (integer)
void echo ( string $arg1 [, string $... ] )
int print ( string $arg )
In PHP, echo is not a function but a language
In PHP, print is not a really function but a
construct.
language construct. However, it behaves like a
function in that it returns a value.
Variables

As with algebra, PHP variables can be used to hold values (x=5) or
expressions (z=x+y).

Variable can have short names (like x and y) or more descriptive names
(age, carname, totalvolume).

Rules for PHP variables:

A variable starts with the $ sign, followed by the name of the variable
Variables

A 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 $Y are two different variables)
Variables

Case-sensitive ($Foo != $foo != $fOo)

Global and locally-scoped variables

Global variables can be used anywhere

Local variables restricted to a function or class

Certain variable names reserved by PHP

Form variables ($_POST, $_GET)

Server variables ($_SERVER)
Creating (Declaring) Variables
<?php
$name = “ali”
echo( $name);
?>
Creating (Declaring) Variables

PHP has no command for declaring a variable.

A variable is created the moment you first assign a value to it:
$txt="Hello world!";
$x=5;

After the execution of the statements above, the variable txt will hold the
value Hello world!, and the variable xwill hold the value 5.

Note: When you assign a text value to a variable, put quotes around the
value.
Variables
<?php
$name = “ali”;
$age = 23;
echo “ My name is $name and I am $age years old”;
?>
PHP is a Loosely Typed Language

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, we will have to declare (define)
the type and name of the variable before using it.
Variables
<?php
$name = 'elijah';
$yearborn = 1975;
$currentyear = 2005;
$age = $currentyear - $yearborn;
echo ("$name is $age years old.");
?>
Variables
<?php
$name = “Ali";
// declaration
?>
<html>
<head> <title>A simple PHP document</title> </head>
<body style = "font-size: 2em">
<p> <strong>
<!-- print variable name’s value -->
Welcome to PHP, <?php echo( "$name" ); ?>!
</strong> </p>
</body>
</html>
PHP Variable Scopes

The scope of a variable is the part of the script where the variable can be
referenced/used.

PHP has four different variable scopes:

local

global

static

Parameter
- In chapter function we will talk about theme.
String Variables in PHP

string variables are used for values that contain characters.

After we have created a string variable we can manipulate it. A string can be used
directly in a function or it can be stored in a variable.

In the example below, we create a string variable called txt, then we assign the text
"Hello world!" to it. Then we write the value of the txt variable to the output:
<?php
$txt="Hello world!";
echo $txt;
?>
PHP strings can be specified in four ways

Single quoted strings will display things almost completely "as is." Variables and most escape
sequences will not be interpreted. The exception is that to display a literal single quote, you can
escape it with a back slash \', and to display a back slash, you can escape it with another
backslash \\ (So yes, even single quoted strings are parsed).
<?php
<?php
?>
$txt = ‘my string ‘;
$txt = ‘my string ‘;
echo $txt; // my string
echo ‘$txt’; // $txt
?>
PHP strings can be specified in four ways

Double quote strings will display a host of escaped characters (including some regexes), and
variables in the strings will be evaluated. An important point here is that you can use curly
braces to isolate the name of the variable you want evaluated. For example let's say you have
the variable $type and you what to echo "The $types are" That will look for the
variable $types. To get around this use echo "The {$type}s are" You can put the left brace
before or after the dollar sign. Take a look at string parsing to see how to use array variables
and such.
<?php
?>
<?php
$txt = “my string”;
$txt = “my string “;
echo $txt; // my string
echo “$txt”; // my string
?>
PHP strings can be specified in four ways

Heredoc string syntax works like double quoted strings. It starts with <<<. After this operator,
an identifier is provided, then a newline. The string itself follows, and then the same identifier
again to close the quotation. You don't need to escape quotes in this syntax.

Nowdoc (since PHP 5.3.0) string syntax works essentially like single quoted strings. The
difference is that not even single quotes or backslashes have to be escaped. A nowdoc is
identified with the same <<< sequence used for heredocs, but the identifier which follows is
enclosed in single quotes, e.g. <<<'EOT'. No parsing is done in nowdoc.
PHP strings can be specified in four ways

Heredoc
<?php
$name='MyName';
echo <<<EOT
My name is "$name".
I am printing some A Now,
I am printing some {A}.
This should print a capital 'A': \x41
EOT;
?>
My name is "MyName". I am printing some A Now,
I am printing some {A}.
This should print a capital 'A': A
PHP strings can be specified in four ways

Nowdoc
<?php
$name='MyName';
echo <<<'EOT'
My name is "$name".
I am printing some A Now,
I am printing some {A}.
This should print a capital 'A': \x41
EOT;
?>
My name is "$name".
I am printing some A Now,
I am printing some {A}. This should print a capital 'A': \x41
Single & Double Quotes
<?php
echo “ Hello world <br>”;
echo ‘ Hello world’;
?>
Single & Double Quotes
<?php
$word = ‘ World’;
echo “ Hello $word <br>”;
echo ‘ Hello $word <br>’;
?>
Comments in PHP
•
// or # for single line
•
/* */ for multiline
•
/*
this is my comment one
this is my comment two
this is my comment three
*/
Whitespace
•
You cant have any whitespace between <? and php.
•
You cant break apart keywords (e.g :whi le,func
tion,fo r)
•
You cant break apart varible names and function
names (e.g:$var name,function f 2)
The PHP Concatenation Operator

here is only one string operator in PHP.

The concatenation operator (.) is used to join two string values together.

The example below shows how to concatenate two string variables together:
<?php
$txt1="Hello!";
$txt2=" world !";
echo $txt1 . " " . $txt2; // Hello world !
?>
The PHP Concatenation Operator
<?php
$string1=“Hello”;
$string2=“PHP”;
$string3=$string1 . “ ” . $string2;
Print $string3;
?>
Hello PHP
Escaping the Character
• If the string has a set of double quotation marks that must
remain visible, use the \ [backslash] before the quotation marks
to ignore and display them.
<?php
$heading="\"Computer Science\""."<br>";
$heading1=@"Computer Science";
echo $heading;
echo $heading1;
?>
"Computer Science"
Computer Science
Example
<?php
$foo = 25;
// Numerical variable
$bar = “Hello”; // String variable
echo $bar;
// Outputs Hello
echo $foo,$bar; // Outputs 25Hello
echo “5x5=”,$foo;
// Outputs 5x5=25
echo “5x5=$foo”;
// Outputs 5x5=25
echo ‘5x5=$foo’;
// Outputs 5x5=$foo
?>
•
Notice how echo ‘5x5=$foo’ outputs $foo rather than replacing it with 25
•
Strings in single quotes (‘ ’) are not interpreted or evaluated by PHP
•
This is true for both variables and character escape-sequences (such as “\n” or “\\”)
Data type
Data type
int,
integer
float,
double
string
bool,
Boolean
array
object
Resource
NULL
Description
Whole numbers (i.e., numbers without a decimal point).
Real numbers (i.e., numbers containing a decimal point).
Text enclosed in either single ('') or double ("") quotes.
True or false.
Group of elements of the same type.
Group of associated data and methods.
An external data source.
No value.
Get type

gettype — Get the type of a variable

Returns the type of the PHP variable var.
<?php
$a = 1;
$b = 1.2;
$c = "abc";
echo gettype($a)."<br>";
echo gettype($b)."<br>";
echo gettype($c)."<br>";
?>
integer
double
string
Set type
<?php
$foo = "5bar"; // string
$bar = true; // boolean
settype($foo, "integer"); // $foo is now 5 (integer)
settype($bar, "string"); // $bar is now "1" (string)
?>
Set type
<?php
$testString = “10.2abc”;
// call function settype to convert variable
// testString to different data types
print( "$testString" );
settype( $testString, "double" );
print( " as a double is $testString <br />" );
print( "$testString" );
settype( $testString, "integer" );
print( " as an integer is $testString <br />" );
settype( $testString, "string" );
print( "Converting back to a string results in
$testString <br /><br />" );
10.2abc as a double is 10.2
10.2 as an integer is 10
Converting back to a string results in 10
Casting Data type
<?php
$data = "98.6 degrees";
Now using type casting instead:
As a string - 98.6 degrees
As a double - 98.6
As an integer - 98
echo "Now using type casting instead: <br>";
echo "As a string - ".(string) $data ;
echo "<br> As a double - ".(double) $data;
echo "<br> As an integer - ".(integer) $data;
?>
Casting Data type
$variable = (datatype) $variable or value
<?php
$data = "98.6 degrees";
echo "Now using type casting instead: <br>";
echo "As a string - ".(string) $data ;
echo "<br> As a double - ".(double) $data;
echo "<br> As an integer - ".(integer) $data;
?>
Casting Data type
<?php
$a = “ 12.4 abc”
echo (int) $a;
echo (double) ($a);
echo (float) ($a);
echo (string) ($a);
?>
PHP Operators
•
•
•
The assignment operator = is used to assign values to
variables in PHP.
The arithmetic operator + is used to add values
together in PHP.
Assignment operators
 Syntactical
shortcuts
 Before being assigned values, variables have value undef
•
Constants
Named values
 define function

PHP Operators
•
•
•
•
•
Arithmetic Operators
Assignment Operators
Incrementing/Decrementing Operators
Comparison Operators
Logical Operators
Arithmetic Operators
Operator
Name
Description
Example
Result
x+y
Addition
Sum of x and y
2+2
4
x-y
Subtraction
Difference of x and y
5-2
3
x*y
Multiplication
Product of x and y
5*2
10
x/y
Division
Quotient of x and y
15 / 5
3
x%y
Modulus
Remainder of x divided by y
5%2
10 % 8
10 % 2
1
2
0
-x
Negation
Opposite of x
-2
a.b
Concatenation
Concatenate two strings
"Hi" . "Ha"
HiHa
Assignment Operators
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
a .= b
a=a.b
Concatenate two strings
Arithmetic Operations
<?php
$a=15;
$b=30;
$total=$a+$b;
echo $total;
echo“<p><h1>$total</h1>”;
// total is 45
?>
•
•
•
•
$a - $b
$a * $b
$a / $b
$a += 5
// subtraction
// multiplication
// division
// $a = $a+5 Also works for *= and /=
Incrementing/Decrementing Operators
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
Arithmetic Operations
<?php
$a =1;
echo $a++;
// output 1,$a is now equal to 2
echo ++$a;
// output 3,$a is now equal to 3
echo --$a;
// output 2,$a is now equal to 2
echo $a--;
// output 2,$a is now equal to 1
?>
Arithmetic Operations
<?php
$num1 = 10;
$num2 =20;
// addition
echo $num1+$mum2 . ‘<br>’;
//subtraction
echo $num1 - $num2 . ‘<br>’;
// multiplication
?>
Arithmetic Operations
<?php
// Multiplication
echo $num1* $num2 . ‘<br>’;
// Division
Echo $num1/num2 . ‘<br>’ ;
//increment
$num1++;
$Num2--;
Echo $num1;
?>
Arithmetic Operations
<?php
$a =(int)(‘test’); // $a==0
echo ++$a;
?>
Dumps information about a variable
void var_dump ($expression [,... ] )

This function displays structured information about one or more expressions that
includes its type and value. Arrays and objects are explored recursively with values
indented to show structure.
<?php
$b = 3.1;
$c = true;
var_dump($b);
var_dump($c);
//or var_dump($b,$c);
?>
float 3.1
boolean true
Comparison Operators
Operator
Name
Description
Example
x == y
Equal
True if x is equal to y
5==8 returns false
x === y
Identical
True if x is equal to y, and they are of same
type
5==="5" returns false
x != y
Not equal
True if x is not equal to y
5!=8 returns true
x <> y
Not equal
True if x is not equal to y
5<>8 returns true
x !== y
Not identical
True if x is not equal to y, or they are not of
same type
5!=="5" returns true
x>y
Greater than
True if x is greater than y
5>8 returns false
x<y
Less than
True if x is less than y
5<8 returns true
x >= y
Greater than or equal to
True if x is greater than or equal to y
5>=8 returns false
x <= y
Less than or equal to
True if x is less than or equal to y
5<=8 returns true
Comparison Operators
<?php
var_dump(0 == "a"); // 0 == 0 -> true
var_dump("1" != "01"); // 1 != 1 -> false
var_dump("10" == "1e1"); // 10 == 10 -> true
var_dump("10" == "1ee1"); // 10 == 1 -> false
var_dump(100 === "100"); // 100 == 100 -> false
var_dump("100" === "100"); // 100 == 100 -> true
?>
boolean true
boolean false
boolean true
boolean false
boolean false
boolean true
Logical Operators
Operator
Name
Description
Example
x and y
And
True if both x and y are true
x=6
y=3
(x < 10 and y > 1) returns true
x or y
Or
True if either or both x and y are true
x=6
y=3
(x==6 or y==5) returns true
x xor y
Xor
True if either x or y is true, but not both
x=6
y=3
(x==6 xor y==3) returns false
x && y
And
True if both x and y are true
x=6
y=3
(x < 10 && y > 1) returns true
x || y
Or
True if either or both x and y are true
x=6
y=3
(x==5 || y==5) returns false
!x
Not
True if x is not true
x=6
y=3
!(x==y) returns true
Logical Operators
<?php
$a = (false && true);
$b = (true || false);
$c = (false and flase);
$d = (true or true);
$e = false || true;
$f = false or true;
var_dump($e, $f);
$g = true && false;
$h = true and false;
var_dump($g, $h);
?>
boolean true
boolean false
boolean false
boolean true
Define function - constant VALUE
define( variable name as string , value );

Variable name as string : the name of variable in single or double quotation
.
<?php
define(‘variable ’,10);
echo variable ; //10
?>
Define function - constant VALUE
<?php
$a = 5;
print( "The value of variable a is $a <br />" );
// define constant VALUE
define( "VALUE", 5 );
// add constant VALUE to variable $a
$a = $a + VALUE;
print( "Variable a after adding constant VALUE
is $a <br />" );
Define function - constant VALUE
// multiply variable $a by 2
$a *= 2;
print( "Multiplying variable a by 2 yields $a <br />" );
// test if variable $a is less than 50
if ( $a < 50 )
print( "Variable a is less than 50 <br />" );
// add 40 to variable $a
$a += 40;
print( "Variable a after adding 40 is $a <br />" );
// test if variable $a is 50 or less
if ( $a < 51 )
print( "Variable a is still 50 or less<br />" );
// test if variable $a is between 50 and 100, inclusive
elseif ( $a < 101 )
print( "Variable a is now between 50 and 100, inclusive<br />" );
else
print( "Variable a is now greater than 100<br />" );
Define function - constant VALUE
// print an uninitialized variable
print( "Using a variable before initializing:
$nothing <br />" );
// add constant VALUE to an uninitialized variable
$test = $num + VALUE;
print( "An uninitialized variable plus constant
VALUE yields $test <br />" );
// add a string to an integer
$str = "3 dollars";
$a += $str;
print( "Adding a string to variable a yields $a
<br />" );
?>
Referencing Operators

We know the assignment operators work by value ,by copy the value to other
expression ,if the value in right hand change the value in left is not change .

Ex:
<?php
$a =10;
$b =$a;
$b =20
Echo $a; // 10
?>
Referencing Operators

But we can change the value of variable $a by the reference , that mena connect
right hand to left hand ,

Example:
<?php
$a =10;
$b = &$a;
$b= 20;
echo $a; // 20
?>
PHP Conditional Statements

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:

if statement - executes some code only if a specified condition is true

if...else statement - executes some code if a condition is true and another code
if the condition is false

if...else if....else statement - selects one of several blocks of code to be
executed

switch statement - selects one of many blocks of code to be executed
The if Statement
•
The if statement is used to execute some code only if a specified condition is true.
if (condition)
{
code to be executed if condition is true;
}
<?php
$t=5;
if ($t<10)
{
echo "hello john";
}
?>
hello john
The if...else Statement
•
Use the if....else statement to execute some code if a condition is true and another
code if the condition is false.
if (condition)
{
code to be executed if condition is true;
}
else
{
code to be executed if condition is false;
}
The if...else Statement
<?php
$t=55;
if ($t<20)
{
echo "Have a good day!";
}
else
{
echo "Have a good night!";
}
?>
Have a good night!
The if...else if....else Statement
•
Use the if....else if...else statement to select one of several blocks of code to be
executed.
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
<?php
$t=7;
if ($t<10)
{
echo "Have a good morning!";
}
else if ($t<20)
{
echo "Have a good day!";
}
else
{
echo "Have a good night!";
}
?>
Have a good morning!
The switch Statement
•
Use the switch statement to select one of many blocks of code to be executed.
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;
}
The switch Statement
<?php
$favcolor="red";
switch ($favcolor)
{
case "red":
echo "Your favorite color is red!";
break;
case "blue":
echo "Your favorite color is blue!";
break;
Your favorite color is red!
case "green":
echo "Your favorite color is green!";
break;
default:
echo "Your favorite color is neither red, blue, or green!";
}
?>
PHP Loops
•
Loops execute a block of code a specified number of times, or while a specified
condition is true.
•
In PHP, we have the following looping statements:
•
while - loops through a block of code while a specified condition is true
•
do...while - loops through a block of code once, and then repeats the loop as
long as a specified condition is true
•
for - loops through a block of code a specified number of times
•
foreach - loops through a block of code for each element in an array
The while Loop
•
The while loop executes a block of code while a condition is true.
while (condition)
{
code to be executed;
}
The number is 1
The number is 2
The number is 3
The number is 4
The number is 5
<?php
$i=1;
while($i<=5)
{
echo "The number is " . $i . "<br>";
$i++;
}
?>
The do...while Statement
•
The do...while statement will always execute the block of code once, it will then
check the condition, and repeat the loop while the condition is true.
do
{
code to be executed;
}
<?php
while (condition);
$i=1;
The
do
{
The
$i++;
The
echo "The number is " . $i . "<br>";
The
}
The
while ($i<=5);
?>
number is 2
number is 3
number is 4
number is 5
number is 6
The do...while Statement
<?php
$i=1;
do
{
$i++;
echo "The number is " . $i . "<br>";
}
while ($i<=5);
?>
The number is 2
The number is 3
The number is 4
The number is 5
The number is 6
The for Loop
•
The for loop is used when you know in advance how many times the script should run.
for (init; condition; increment)
{
code to be executed;
}
•
Parameters:
•
init: Mostly used to set a counter (but can be any code to be executed once at
the beginning of the loop)
The for Loop
• condition: Evaluated for each loop iteration. If it evaluates to TRUE, the
loop continues. If it evaluates to FALSE, the loop ends.
• increment: Mostly used to increment a counter (but can be any code to
be executed at the end of the iteration)
• Note: The init and increment parameters above can be empty or
have multiple expressions (separated by commas).
The for Loop
<?php
for ($i=1; $i<=5; $i++)
{
echo "The number is " . $i . "<br>";
}
?>
The number is 1
The number is 2
The number is 3
The number is 4
The number is 5
The foreach Loop
• The foreach loop is used to loop through arrays.
• We well talk about this in chapter array
Isset Function
•
bool isset ( $var )
•
Determine if a variable is set and is not NULL.
•
If a variable has been unset with unset(), it will no longer be set. isset() will
return FALSE if testing a variable that has been set to NULL. Also note that
a NULLbyte ("\0") is not equivalent to the PHP NULL constant.
•
If multiple parameters are supplied then isset() will return TRUE only if all of the
parameters are set. Evaluation goes from left to right and stops as soon as an unset
variable is encountered.
Isset Function
<?php
$var = '';
// This will evaluate to TRUE so the text will be printed.
if (isset($var))
{
echo "This var is set so I will print.";
}
?>
Unset Function
•
void unset ( $var)
•
unset() destroys the specified variables.
•
The behavior of unset() inside of a function can vary depending on what type of
variable you are attempting to destroy.
•
If a globalized variable is unset() inside of a function, only the local variable is
destroyed. The variable in the calling environment will retain the same value as
before unset() was called.
unset Function
<?php
$foo = 'bar';
echo $foo;
unset($foo);
echo $foo;
?>
Info PHP Page
<?php
phpinfo();
?>
Goto
<?php
goto a;
echo 'Foo';
a:
echo 'Bar';
?>
<?php
for($i=0,$j=50; $i<100; $i++) {
while($j--) {
if($j==17) goto end;
}
}
echo "i = $i";
end:
echo 'j hit 17';
?>
Chapter Example
if/else if/else statement
<?php
if ($foo == 0) {
echo ‘The variable foo is equal to 0’;
}
else if (($foo > 0) && ($foo <= 5)) {
echo ‘The variable foo is between 1 and 5’;
}
else {
echo ‘The variable foo is equal to ‘.$foo;
}
?>
Switch Statment
<?php
$count=0;
switch($count)
{
case 0:
echo “hello PHP3. ”;
break;
case 1:
echo “hello PHP4. ”;
break;
default:
hello PHP3
echo “hello PHP5. ”;
break;
}
?>
Switch - Example
<?php
$total = 0;
$i = 2;
switch($i) {
case 6: $total = 99; break;
case 1: $total += 1;break;
case 2:$total += 2;break;
case 3: $total += 3; ;break;
case 4:$total += 4; break;
default : $total += 5;break;
}
echo $total;
?>
2
For Loop
<?php
$count=0;
for($count = 0;$count <3,$count++)
{
Print “hello PHP. ”;
}
?>
hello PHP. hello PHP. hello PHP.
For - Example
<?php
for ($i = 1; $i <= 10; $i++) {
echo $i;
}
?>
For-Example
<?php
$brush_price = 5;
echo "<table border=\"1\" align=\"center\">";
echo "<tr><th>Quantity</th>";
echo "<th>Price</th></tr>";
for ( $counter = 10; $counter <= 100; $counter += 10)
{
echo "<tr><td>";
echo $counter;
echo "</td><td>";
echo $brush_price * $counter;
echo "</td></tr>";
}
echo "</table>";
?>
While Loop
<?php
$count=0;
while($count<3)
{
echo “hello PHP. ”;
$count += 1;
// $count = $count + 1;
// or
// $count++;
}
?>
hello PHP. hello PHP. hello PHP.
While - Example
<?php
$i = 0;
while ($i++ < 5)
{
echo “loop number : “.$i;
}
?>
Do ... While Loop
<?php
$count=0;
do
{
echo “hello PHP. ”;
$count += 1;
// $count = $count + 1;
// or
// $count++;
}
while($count<3);
?>
hello PHP. hello PHP. hello PHP.
Do..While
<?php
$i = 0;
do {
echo $i;
} while ($i > 0);
?>
For..If
<?php
$rows = 4;
echo '<table><tr>';
for($i = 0; $i < 10; $i++){
echo '<td>' . $i . '</td>';
if(($i + 1) % $rows == 0){
echo '</tr><tr>';
}
}
echo '</tr></table>';
?>
For
<?php
//this is a different way to use the 'for'
//Essa é uma maneira diferente de usar o 'for'
for($i = $x = $z = 1; $i <= 10;$i++,$x+=2,$z=&$p){
$p = $i + $x;
echo "\$i = $i , \$x = $x , \$z = $z <br />";
}
?>
Nested For
<?php
for($a=0;$a<10;$a++){
for($b=0;$b<10;$b++){
for($c=0;$c<10;$c++){
for($d=0;$d<10;$d++){
echo $a.$b.$c.$d.", ";
}
}
}
}
?>
While - Switch
<?php
$i = 0;
while (++$i) {
switch ($i) {
case 5:
echo "At 5<br />\n";
break 1; /* Exit only the switch. */
case 10:
echo "At 10; quitting<br />\n";
break 2; /* Exit the switch and the while. */
default:
break;
}
}
?>
Continue
<?php
for ($i = 0; $i < 5; ++$i) {
if ($i == 2)
continue
print "$i\n";
}
?>
If - Switch
<?php
$i = 1;
if ($i == 0) {
echo "i equals
} elseif ($i == 1)
echo "i equals
} elseif ($i == 2)
echo "i equals
}
0";
{
1";
{
2";
switch ($i) {
case 0:
echo "i equals 0";
break;
case 1:
echo "i equals 1";
break;
case 2:
echo "i equals 2";
break;
}
?>
Do..While - IF
<?php
do {
if ($i < 5) {
echo "i is not big enough";
break;
}
$i *= $factor;
if ($i < $minimum_limit) {
break;
}
echo "i is ok";
/* process i */
} while (0);
?>
If in other style
<?php
$hour = 11;
echo $foo = ($hour < 12) ? "Good morning!" : "Good
afternoon!";
?>