Chapter 3: PHP Language (II)

Chapter 3: PHP Language (II)Chapter 3: PHP Language (II)

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OverviewOverview

Arrays Flow Control – foreach Functions of Strings Object Oriented Exception Handling

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Arrays (1)Arrays (1)

Something like cabinets.• You can put something in it.

• You can leave some empty space in.

Two types:• Indexed Arrays

Index # Value

• Associative Arrays Key Value

※ These two types can be mix-used,but No duplicate index numbers or keys are allowed!

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Indexed Arrays• Index # Value

• The default start number of index is zero.

• Ex.

• To indicate one elements in array:$ary_name[idx_num] Ex. $ary[3]

0 1 2 3 4 5 6 7 8 9

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Index

$ary[] Element of $ary[]with index=5

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• Construction Need no declaration. Two methods:

– Using 「 array()」 .

– Assign values directly.

$scores = array (80, 65, 89, 93);echo $scores[0]; // output 80echo $scores[1]; // output 65echo $scores[2]; // output 89echo $scores[3]; // output 93print_r ($scores);

Array(

[0] => 80[1] => 65[2] => 89[3] => 93

)

$scores[0] = 80;$scores[1] = 65;$scores[2] = 89;$scores[3] = 93;print_r ($scores);

print_r:Prints human-readable information about a variable

＝$scores[] = 80;$scores[] = 65;$scores[] = 89;$scores[] = 93;

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Associative Arrays• Key Value

• Ex.

• To indicate one elements in array:$ary_name[key] Ex. $ary[‘John’]

Bob 80

John 65

Mary 89

Andy 93

Alice 80

Berry 95

Key$ary[]

Element of $ary[]with key=Alice

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• Construction Need no declaration. Two methods:

– Using 「 array( Key=>Value)」 .

– Assign Key & Value directly.

$scores = array('Bob'=>80, 'John'=>65, 'Mary'=>89, 'Andy'=>93 );

print_r ($scores);

Array(

[Bob] => 80[John] => 65[Mary] => 89[Andy] => 93

)

$scores['Bob'] = 80;$scores['John'] = 65;$scores['Mary'] = 89;$scores['Andy'] = 93;print_r ($scores);

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Accessing arrays• Reading

$ary_name[ idx_num or key ]

$scores = array (80, 65, 89, 'Andy'=>93);$c = $scores[2];$d = $scores['Andy'];echo $c; // output 89echo $d; // output 93echo $scores[1]; // output 65echo $scores['Andy']; // output 93

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• Adding/Modifying$ary_name[ idx_num or key ] = expression;

To change the index value while adding.

$scores = array (80, 65, 89, 'Andy'=>93);$scores[1] = 70;$scores['Andy'] = 95;$scores[3] = 86;echo $scores[1]; // output 70echo $scores['Andy']; // output 95echo $scores[3]; // 86print_r($scores);

Array(

[0] => 80[1] => 70[2] => 89[Andy] => 95[3] => 86

)

$scores = array (80, 65, 6=>89, 93);$scores[] = 88;print_r($scores);

Array(

[0] => 80[1] => 70[6] => 89[7] => 93[8] => 88

)

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• Deletingunset ( $ary_name[ idx_num or key ] );

$scores = array (80, 65, 89, 'Andy'=>93);unset ( $scores[1] );unset ( $scores['Andy'] );print_r($scores);

Array(

[0] => 80[2] => 89

)

$scores = array (80, 65, 89, 93);unset ( $scores[2] );$scores[2] = 76;print_r($scores);

Array(

[0] => 80[1] => 65[3] => 93[2] => 76

)

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Practicing• 1. Print the List Array

• 2. Print the Associate Array

• 3. Add Jaina to the Associate Array like

• 4. Edit John’s Score to 40 and Delete David’s Data.

Array( [0] => Charlie [1] => John [2] => David)

Array( [Charlie] => 84 [John] => 47 [David] => 29)

Array( [Charlie] => 84 [John] => 47 [David] => 29 [Jaina] => 77)

Array( [Charlie] => 84 [John] => 40 [Jaina] => 77)

http://tphp.cs.nctu.edu.tw/tphp/pr3-1_1.phphttp://tphp.cs.nctu.edu.tw/tphp/pr3-1_1.txt




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2-Dimentional Array• Something likes matrix.

• One array, each elementin it is also array.

• Notation$ary_name[key1][key2]

• Example$name_score[“David”][“score”] = “77”;

Not This

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Array Operators

Operator Description Example

+Union of two arrays.

※It appends the right handed array to the left handed, whereas duplicated keys are NOT overwritten.

$a + $b

= Copy one away to another. ( to copy, not reference)※ $b = $a

== TRUE if two arrays have the same key/value pairs. $a == $b

===TRUE if two arrays have the same key/value pairs in the same order and of the same types.

$a === $b

!=, <> TRUE if two arrays are not equal. $a != $b

!== TRUE if two arrays are not identical. $a !== $b

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• Examples

$a = array("a" => "apple", "b" => "banana");$b = array("a" => "pear", "b" => "strawberry", "c" => "cherry");

print_r ( $a + $b ); // Union of $a and $bprint_r ( $b + $a ); // Union of $b and $a

Array( [a] => apple [b] => banana [c] => cherry)Array( [a] => pear [b] => strawberry [c] => cherry)

$a = array( 70, 80); $b = array( 70, "80");echo ($a==$b) ? "equal" :"not equal"; // output equalecho ($a===$b)? "identical" : "not identical"; // output not identical

Array( [x] => 70 [y] => 80)Array( [y] => 80 [x] => 70)

$a = array( "x"=>70, "y"=>80);$b = array( "y"=>80, "x"=>70);print_r($a);print_r($b);echo ($a==$b) ? "equal" :"not equal"; // output equalecho ($a===$b)? "identical" : "not identical"; // output not indentical

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Functions for Arrays[Ref] http://www.php.net/manual/en/ref.array.php

• Getting Properties count(array) – getting array size (# of elements)

• Accessing array_pad(array) – Pad array to the specified length with a value. array_unique(array) – Returns a new array without duplicate values. array_reverse(array) – Return an array with elements in reverse order. array_keys(array) – Return all the keys of an array. array_values(array) – Return all the values of an array.

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• Using Array’s Internal Pointer reset, next, prev, end

– Moving Internal Pointer

current, key– Get value/key of the record pointed by I.P.

list(var1, var2, …) – Assign variables as if they were an array.$box = array ( 200, 80, 70);

list ($x, $y, $z) = $box; //$x=200, $y=80, $z=70

each(array)– Return the current key and value pair from an array, advance the array

cursor.

$a = array ( 60, 50, 40);while (list ($k, $v) = each($a)) echo "$k = $v";

0 = 60 1 = 50 2 = 40

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• Sorting In Arrays sort, rsort

– Sort an array

asort, arsort– Sort an array and maintain index association

ksort, krsort– Sort an array by key. (will also keep index association)

Example

echo " \n";$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");$s = $fruits; sort($s);$a = $fruits; asort($a);$k = $fruits; ksort($k);print_r($s);print_r($a);print_r($k);

Array([0] => apple[1] => banana[2] => lemon[3] => orange)

Array([c] => apple[b] => banana[d] => lemon[a] => orange)

Array([a] => orange[b] => banana[c] => apple[d] => lemon)

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• Searching In Arrays in_array($value, $array, [$bool])

– Return TRUE if value exists in array.

array_search ($value, $array, [$bool])– Return index/key.

Example

$os = array("Mac", "NT", "Irix", "Linux");if (in_array("Irix", $os)) echo "Got Irix";if (in_array("mac", $os)) echo "Got mac";

Got Irix

$array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red');

$key = array_search('green', $array); // $key = 2;$key = array_search(‘yellow', $array); // $key = false;

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Practicing• 1. Sort the score list and Print it (from high to low).

• 2. Find if 77, 32 are in the list.

7478257595581211469306038351006961024256557602342773299550

http://tphp.cs.nctu.edu.tw/tphp/pr3-2_1.phphttp://tphp.cs.nctu.edu.tw/tphp/pr3-2_1.txthttp://tphp.cs.nctu.edu.tw/tphp/pr3-2_2.phphttp://tphp.cs.nctu.edu.tw/tphp/pr3-2_2.txt

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Flow Control – foreach (1)Flow Control – foreach (1)

How to get every keys & values in an array?• “print_r” only print it out, not accessible.

• How about this?

Only suitable for indexed arrays, andnot allowing “holes” in arrays.

• Better one

But too complex

for ( $i = 0; $ary[$i] != NULL; $i++){ … // $i is index, $ary[$i] is value}

reset($ary);while (($v=current($ary))!=NULL){ $k = key($ary); … // $k is key, $v is value next($ary);}

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• Rewrite to “for loop”

Seems better, but… I don’t like it.

• Using foreach

Syntax:

foreach ($array as $key => $value) {

…

}

foreach ($array as $value) { // when $key not needed

…

}

for(reset($ary);$v=current($ary);next($ary)){ $k = key($ary); … // $k is key, $v is value}

foreach ($ary as $k => $v){ … // $k is key, $v is value}

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• Another approach – using list & each

Syntax:

reset($array);

while ( list($key, $value)=each($array)) {

…

}

reset($array);

while ( list(, $value)=each($array)) { // when $key not needed

…

}

reset($ary);while (list($k, $v)=each($ary)) { … // $k is key, $v is value}

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Practicing• 1. Use foreach to dump the score list.

• 2. Use while to dump the score list.

• 3. Use foreach to dump the score list twice.

• 4. Use while to dump the score list twice.

Array( [Charlie] => 84 [John] => 47 [David] => 29 [Jaina] => 77)





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Functions of Strings (1)Functions of Strings (1)

Strings – Characters connected, quoted with ‘’ or “” Useful functions

[Ref] http://www.php.net/manual/en/ref.strings.php

• Getting Properties strlen(string) – Get string length.

Example

$str = 'abcdef';echo strlen($str); // 6

$str = ' ab cd ';echo strlen($str); // 7

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• Transformation trim, ltrim, rtrim, chop – Strip whitespace of a string.

– trim – From the beginning and end of a string.

– ltrim – From the beginning of a string.

– rtrim – From the end of a string.

– chop – The same with rtrim.

strtolower, strtoupper – Make a string lowercase/uppsercase. strrev – Reverse a string. str_repeat(string, times) – Repeat string $times times.

Example

$text = "\t\tA few words :) ... ";echo trim($text); // "A few words :) ..."echo trim($text, " \t."); // “A few words :)"

$str = “HELLO";$str = strtolower($str);echo $str; // hello

echo strrev("Hello world!"); // outputs "!dlrow olleH"

echo str_repeat("-=", 5); // outputs “-=-=-=-=-=“

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• Searching/Tokenizing substr – Return part of a string. strpos, strrpos – Find position of first/last occurrence of a string. strstr, stristr, strchr, strrchr

– Return remaining sub-string while matching first/last occurrence of a string.

substr_count – Count the number of substring occurrences.

Example

echo substr('abcdef', 1); // bcdefecho substr('abcdef', 1, 3); // bcdecho substr('abcdef', 0, 4); // abcdecho substr('abcdef', 0, 8); // abcdefecho substr('abcdef', -1, 1); // f

$newstring = 'abcdef';$pos = strpos($newstring, 'a'); // $pos = 0

$email = '[email protected]';$domain = strstr($email, '@');echo $domain; // prints @example.com

$text = 'This is a test';echo substr_count($text, 'is'); // 2

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Practicing

• 1. Find length of this String.

• 2. Strip head/end whitespace of this String and show length.

• 3. Make this String to uppercase and print it.

• 4. Print first 20 character of this string.

• 5. Find ‘enables’ first occurrence position.

“ WaSP issues an open invitation to work with Assistive Technology Vendors to help ensure greater support for standards-based web development techniques in software that enables access for millions of people worldwide. “






http://tphp.cs.nctu.edu.tw/tphp/pr3_4_string.txt

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Further Study: Regular Expression• Functions

ereg, eregi– Regular expression match.

split, spliti– Split string into array by regular expression.

ereg_replace, eregi_replace– Replace regular expression.

preg_*– Using perl-compatible regular expression.

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• Example

$date = “2006-11-12”;if (ereg ("([0-9]{4})-([0-9]{1,2})-([0-9]{1,2})", $date, $regs)) { echo "$regs[3].$regs[2].$regs[1]"; // outputs “12.11.2006” } else { echo "Invalid date format: $date";}

$date = "04/30/1973";list($month, $day, $year) = split('[/]', $date);echo "Month: $month, Day: $day; Year: $year \n";// outputs “Month:04, Day: 30, Year: 1973”;

$string = "This is a test";echo str_replace(" is", " was", $string); // outputs “This was a test”echo ereg_replace("( )is", "\\1was", $string); // outputs “This was a test”echo ereg_replace("(( )is)", "\\2was", $string); // outputs “This was a test”

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Object Oriented (1)Object Oriented (1)

PHP supports OOP (Object-Oriented Programming)

Basic Properties of Object• State member data• Behavior member functions• Identity object name (like variable name)

OOP• Languages that supports 3 object-oriented characteristics.

Encapsulation– Encapsulate variables & functions to be an object.

Inheritance– Reuse existing objects.

Polymorphism– Using same code handling different types of data types.

variables

method

method

methodmethod

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Class and Object• Class

The blueprint of object Contains the definition of “member data” and “member functions”

• Defining Classesclass classname {

var $var1;

var $var2, $var3;

function __construct ($invar1, $invar2, …){ …}

function __destruct () {…}

function member_func ($invarx, $invary, …) {…}

}

• Creating Objects$obj = new classname($arg1, $arg2, …);

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• Example

class Student { var $id, $name; function setid($newid){ //do nothing }}

$s1 = new Student();print_r ($s1);

student Object(

[id] =>[name] =>

)

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• Accessing member data & Calling member function Inner object

Member data: $this -> varname

Member function: $this -> member_fun($arg1, $arg2, …) Out of object

Member data: $obj -> varname

Member function: $obj -> member_fun($arg1, $arg2, …)

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• Example

class Student { var $id, $name; function setid($newid){ $this->id = $newid; } function getid(){ return $this->id; }}

$s1 = new Student(); $s2 = new Student();

$s1->id = "9412345";echo "Student1 ID:", $s1->id; // output 9412345

$s2->setid("9654321");echo "Student2 ID:", $s2->getid(); // output 9654321

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• Constructor and Destructor Constructor

– The initial function object generated.

function __constructor ($invar1, $invar2, …) { … } Destructor

– The final function before object die.

function __destructor () { … } There are no return values in both constructors and destructors.

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• Example

class MyDestructableClass { function __construct() { print "In constructor\n"; $this->name = "MyDestructableClass"; }

function __destruct() { print "Destroying " . $this->name . "\n"; }}

$obj = new MyDestructableClass();

In constructorDestroying MyDestructableClass

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• Visibility of member data/functions private

– Only visible inner class itself.

public– Visible everywhere.

protected– Visible in itself and classes inherit this class.

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• Example

class MyClass{ public $public = 'Public'; protected $protected = 'Protected'; private $private = 'Private';

function printHello() { echo $this->public; echo $this->protected; echo $this->private; }}

$obj = new MyClass();echo $obj->public; // Worksecho $obj->protected; // Fatal Errorecho $obj->private; // Fatal Error$obj->printHello(); // Shows Public, Protected and Private

class MyClass2 extends MyClass{ function printHello() { echo $this->public; echo $this->protected; echo $this->private; }}

$obj2 = new MyClass2();echo $obj->public; // Worksecho $obj2->private; // Undefined (not error)echo $obj2->protected; // Fatal Error$obj2->printHello(); // Shows Public, Protected, not Private

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• Class constant Syntax:

class classname {

const CONSTNAME = value;

} Accessing

– Inner object

» self ::CONSTNAME– Out of object

» classname::CONSTNAME

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• Static member data/functions Syntax:

class classname {

public static $VARIABLE = value;

public static function METHOD() {

………

}

} Accessing

– Inner object

» self::$VARIABLE

» self::METHOD()– Out of object

» classname::$VARIABLE

» classname::METHOD()

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• Exampleclass Foo{ public static $my_static = 'foo';

public function staticValue() { return self::$my_static; }}class Bar extends Foo{ public function fooStatic() { return parent::$my_static; }}print Foo::$my_static . "\n";$foo = new Foo();print $foo->staticValue() . "\n";print $foo->my_static . "\n"; // Undefined "Property" my_static // $foo::my_static is not possibleprint Bar::$my_static . "\n";$bar = new Bar();print $bar->fooStatic() . "\n";

class Foo { public static function aStaticMethod() { // ... }}

Foo::aStaticMethod();

class MyClass{ const constant = 'constant value';

function showConstant() { echo self::constant . "\n"; }}echo MyClass::constant . "\n";$class = new MyClass();$class->showConstant();// echo $class::constant; is not allowed

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Priacticing• Make a Class “Book” who has members: “code”, “title”, “author”, “

price”. Make a constructor function, a function BookCounts() to get how many books there and a function showBook() to print information of a Book. The Book Maximum num is 50.

http://tphp.cs.nctu.edu.tw/tphp/pr3-5.phphttp://tphp.cs.nctu.edu.tw/tphp/pr3-5.txt

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Further Study• Inheritance

class classname extends parent_class {

…

}

• Polymorphism abstract & interface

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Exception Handling (1)Exception Handling (1)

Exceptions (Errors)• Reason

Environmental Programming

• Levels Parse Errors Fatal Errors Warnings Notices

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Exception Handling• Error Reporting

Setting what will be reported:error_reporting ( ERR1 | ERR2 | … );

ERRORS ( Predefined Constants)– E_ALL

– E_ERROR, E_WARNING, E_PARSE, E_NOTICE

– E_CORE_ERROR, E_CORE_WARNING

– E_COMPILE_ERROR, E_COMPILE_WARNING

– E_USER_ERROR, E_USER_WARNING, E_USER_NOTICE

– E_STRICT ( PHP 5.0)≧– E_RECOVERABLE_ERROR ( PHP 5.2)≧

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• Error Handler Setting who (function) will handle errors:

set_error_handler(‘handlername’);

function handlername($type, $msg, $file, $line) {

// $type is error level

// $msg is error info

// $file is the php filename executed

// $line is the line number of code when error happened.

}

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• Logging Errors Error handler can keep logs somewhere he want. Setting where to keep logs:

error_log($msg, OUTPUT_TYPE, $target); OUTPUT_TYPE

– 0 Log to system log

– 1 Log mailed to $target (should be an email address)

– 3 Log to $target (should be a file)

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• User Level Errors User can create some errors in the programs. Generating user level error:

trigger_error($msg, ERROR); ERROR available

– E_USER_ERROR, E_USER_WARNING, E_USER_NOTICE

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• Example// set the error reporting level for this scripterror_reporting(E_USER_ERROR | E_USER_WARNING | E_USER_NOTICE);// error handler functionset_error_handler(“myErrorHandler”);function myErrorHandler($errno, $errstr, $errfile, $errline) { switch ($errno) { case E_USER_ERROR: echo "My ERROR [$errno] $errstr \n"; echo " Fatal error in line $errline of file $errfile"; echo ", PHP " . PHP_VERSION . " (" . PHP_OS . ") \n"; echo "Aborting... \n"; exit(1); break; case E_USER_WARNING: echo "My WARNING [$errno] $errstr \n"; break; case E_USER_NOTICE: echo "My NOTICE [$errno] $errstr \n"; break; default: echo "Unknown error type: [$errno] $errstr \n"; break; }}

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• Example 2// Send notification through the server log if we can not// connect to the database.if (!Ora_Logon($username, $password)) { error_log("Oracle database not available!", 0);}

// Notify administrator by email if we run out of FOOif (!($foo = allocate_new_foo())) { error_log("Big trouble, we're all out of FOOs!", 1, "[email protected]");}

// other ways of calling error_log():error_log("You messed up!", 2, "127.0.0.1:7000");error_log("You messed up!", 2, "loghost");error_log("You messed up!", 3, "/var/tmp/my-errors.log");

if (assert($divisor == 0)) { trigger_error("Cannot divide by zero", E_USER_ERROR);}

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Further Study:• Exception Objects (PHP 5.0)≧

Exception handling likes java, VB.NET, C#, …etc. Generating Exception

throw ExceptionObject;

Handling Exceptiontry{

… // what to do

}catch ( ExceptionClass $exception) {

… // code to handle exceptions

}

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Q&AQ&A

Chapter 3: PHP Language (II)

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Transcript of Chapter 3: PHP Language (II)