Table 3.1. PHP Syntax and Constructs
!"#$%&'( !"#$)*)$(+,-.%$-($./&+#0$1#%2##3$%"#$)*)$4.#3$%&'$
<?php
$&30$%"#$)*)$+/4(#$
%&'$
?>
5$!"#$+40#$1#%2##3$%"#(#$%24$%&'($-($2"&%$%"#$)*)$6407/#$.,4+#((#(5$
!"#$*!89$+40#$-($:7(%$/#;%$&($-($<(##$="&.%#,$>?$@A#%%-3'$B%&,%#0CD5

Instantiating a class: $cat = new Pet; // Create object with a
constructor method $cat->set_name("Sneaky"); // Access object
with an instance method
echo "Your cat is rightly named ",$cat->get_name(),
".<br";
?>
$ )*)$&/(4$(7..4,%($-3"#,-%&3+#5$G$3#2$+/&(($+&3$1#$+,#&%#0$;,46$&3$#Q-(%-3'$
+/&((?$&$.&,#3%b+"-/0$,#/&%-43("-.$2"#,#$%"#$+"-/0$+/&(($-3"#,-%($.,4.#,%-#($&30$
6#%"40($4;$%"#$.&,#3%$+/&(($&30$#Q%#30($4,$0#;-3#($%"#$;73+%-43&/-%H$4;$-%($
.&,#3%5$)*)$&/(4$"&($(.#+-&/$+43(%,7+%4,$&30$0#(+%,7+%4,$6#%"40($;4,$+,#&%-3'$
&30$0#(%,4H-3'$41:#+%(?$&($2#//$&($(.#+-&/$(#%%#,$&30$'#%%#,$6#%"40($<&/(4$
+&//#0$&++#(($4,$-3(%&3+#$6#%"40(D$;4,$&((-'3-3'$&30$,#%,-#L-3'$%"#$41:#+%c($
.,4.#,%-#(5$G3$#Q&6./#$%"&%$+,#&%#($&$3#2$
Laptop
$+/&(($;,46$&$
Computer

$this->password = "urAok5"; // private
}
function setUserId($userId){
$this->userId=$userId;
}
function getUserId() {
return $this->userId;
}
private function setPassword($password){ // private
method
$this->password=$password;
}
private function getPassword(){
return $this->password;
}
}
class Laptop extends Computer{ //
Child/derived/subclass
public $brand;
public $weight;
private $password="LetMeIn2";

function __construct($brand,$weight){ // Subclass
constructor parent::__construct(); // Call to parent's
constructor
echo "Child constructor just called.\n<br />";
$this->brand=$brand; // new properties for

$portable = new Laptop();
$portable->setPassword("letmein2");
.....
]-/#( )*)$+46#($2-%"$&$(#%$4;$17-/%S-3$;73+%-43($%"&%$&//42$H47$%4$24,U$2-%"$;-/#(5$
d47$+&3$-3+/70#$#Q%#,3&/$;-/#($2-%"$%"#$
require
$&30$
include
$(%&%#6#3%(5$!"#$
-3+/70#0$;-/#($+&3$+43(-(%$4;$)*)?$*!89?$F89?$%#Q%?$&30$(4$435$!"#$,#K7#(%#0$
;-/#c($+43%#3%($,#./&+#$%"#$/-3#$+43%&-3-3'$%"#$24,0$
require
$4,$
include
5
$ EFG8)9E
$ !4$-3+/70#$&$;-/#I$$
// replaces instances of require with the contents of
file
require("copyright.inc");
// replaces only first instance of require with
contents of file
require_once("header.inc");
// same as replace but happens only during program
execution
include("disclaimer.inc");
// happens only once during program execution
include_once("title.inc");
$ !4$4.#3$&$;-/#$;4,$,#&0-3'?$2,-%-3'?$&..#30-3'?$&30$(4$43?$%"#$;-/#3&6#$67(%$1#$
&((-'3#0$%4$&$;-/#"&30/#5$!"#$;4//42-3'$-($&$/-(%$4;$(46#$4;$%"#$1&(-+$;73+%-43($

$text = fread($filehandle, $bytes );
// Reads entire contents from "filename"
$text = file_get_contents("filename");

To write to a file:
// Writes $string to $filehandle
fwrite($filehandle, $string);
// Writes $string to "filename"
file_put_contents("filename", $string);
e#'7/&,$
#Q.,#((-43(
)*)$(7..4,%($.&%%#,3$6&%+"-3'$2-%"$,#'7/&,$#Q.,#((-43($&30$,#'7/&,$
#Q.,#((-43$6#%&+"&,&+%#,($<(##$!&1/#$f5>D5$!"#$
pcre
$<)#,/$(%H/#D$;73+%-43($&,#$
7(#0$%4$%#(%$2"#%"#,$&$%#Q%$(%,-3'$6&%+"#($&$.&%%#,35
$ EFG8)9EB
$ =40#$P-#2I$
// $result is 1, $matches contains needle
$result = preg_match("/needle/", "looking for a
needle in a
haystack", $matches);

// Regular expression metacharacters
if ( preg_match("/^[Nn]..dle/", "Needle in a haystack"
)){
echo "Found match.\n";
}
// $new_array contains: normal, mama, man
$new_array = preg_grep("/ma/", array("normal", "mama",

// $new_string: "I am feeling upbeat, upbeat.
$new_string = preg_replace("/blue/i", "upbeat", "I am
feeling BLue, BLUE.");

// $new_string: "War and Peace"
$new_string = preg_replace("/(Peace) and (War)/i", "$2
and $1", "Peace and War");

// $new_string: "He gave me 42 dollars."
$new_string = preg_replace("/5/e", "6*7", "He gave me 5 dollars.")e;
$
$
$
$
$
$
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Table 3.2. Some Regular Expression Metacharacters
Metacharacter What)It)Does
^



8&%+"#($43#$0-'-%$1#%2##3$
0
$&30$
9

ab*c

8&%+"#($&3$
a
?$;4//42#0$1H$Y#,4$4,$64,#$4;$%"#$/#%%#,$
b
?$&30$&$
c

ab+c

8&%+"#($&3$
a
?$;4//42#0$1H$43#$4,$64,#$4;$%"#$/#%%#,$
b
?$&30$&$
c

ab?c

8&%+"#($&3$
a
?$;4//42#0$1H$Y#,4$4,$43#$
b

blocks of a program. They are called scalars and can be assigned a single literal value such as a number, 5.7, or a
string of characters, such as "hello", a date and time, or a boolean (true/false). See Figure 4.1.
Figure 4.1. Scalars hold one value.

!
PHP also supports composite data types, such as arrays and objects. Composite data types represent a collection of data,
rather than a single value (see Figure 4.2). The composite data types are discussed in Chapter 8, “Arrays,” and Chapter
17, “Objects.”
Figure 4.2. Arrays and objects hold multiple values.

!
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The different types of data are commonly stored in variables. Examples of PHP variables are $num = 5 or $name =
"John" where variables $num and $name are assigned an integer and a string, respectively. Variables hold values
that can change throughout the program, whereas once a constant is defined, its value does not change. PHP_VERSION
and PHP_OS are examples of predefined PHP constants. The use of PHP variables and constants is addressed in
“Variables” on page 70 and “Constants” on page 99 of this chapter.
PHP supports four core data types:
• Integer
• Float (also called double)
• String
• Boolean
In addition to the four core data types, there are four other special types:
• Null
• Array
• Object
• Resources
4.1.1. Numeric Literals
PHP supports both integers and floating-point numbers. See Example 4.1.
• Integers— Integers are whole numbers and do not contain a decimal point; for example, 123 and –6. Integers

.</b></em><br />";
print "The number in scientfic notation is <em><b> " . 5e3 . "
. </b></em><br />";
print "\tThe string is: <em><b>I can't help you!</em>
</b><br />";
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?>
</body>
</html>

Figure 4.3. Output from Example 4.2.
!
!
!
4.1.2. String Literals and Quoting
We introduce strings in this chapter but Chapter 6, “Strings,” provides a more comprehensive coverage. String literals
are a row of characters enclosed in either double or single quotes.
[1]
The quotes must be matched. If the string starts with
a single quote, it must end with a matching single quote; likewise if it starts with a double quote, it must end with a
double quote. If a string of characters is enclosed in single quotes, the characters are treated literally (each of the
characters represents itself). We can say the single quotes are the democratic quotes: All characters are treated equally.
[1]
PHP always null-terminates strings internally and keeps track of the length of the string.
Double quotes do not treat all characters equally. If a string is enclosed in double quotes, most of the characters
represent themselves, but dollar signs and backslashes have a special meaning as shown in the following examples.
Single quotes can hide double quotes, and double quotes can hide single quotes:
[2]

[2]

quotes
5 print "<li> I can't go with you.</li>"; // Nested
quotes
6 print "<li> She cried, \"Help!\"</li>"; // Escaping
quotes
7 print "<li> I need \$5.00.</li>"; // The backslash
// quotes one
character
8 print "<li> $name needs ". '$5.00 </li>'; // Nested
quotes
print "</ol>";
?>
</body>
</html>
Explanation
" #$#!%&'(&)*!+,)&,+!-.&./
0
$name
!1+!)!#$#!2)&1)34./!5,!1+!)++1(6.7!,-.!+,&16(!
"Nancy"
/!8'9!:144!4.)&6!)44!
)3'9,!2)&1)34.+!16!,-.!+.;,1'6!<=)&1)34.+>!'6!%)(.!?@/
A B-.6!)!+,&16(!1+!.6;4'+.7!:1,-16!7'934.!C9',.+D!,-.!#$#!16,.&%&.,.&!:144!
+93+,1,9.!,-.!2)&1)34.!:1,-!1,+!2)49.E!F'&!.G)*%4.D!
$name
!:144!3.!&.%4);.7!:1,-!
"Nancy"
/
H B-.6!)!+,&16(!1+!.6;4'+.7!16!+16(4.!C9',.+D!)44!;-)&);,.&+!)&.!,&.),.7!)+!41,.&)4+/!
=)&1)34.!+93+,1,9,1'6!:144!6',!';;9&/

<<<DELIMITER
!
print <<<HERE_DOC_DELIMITER <text here> ... < more text> ...
HERE_DOC_DELIMITER

2.# N-.!7.41*1,.&!;)66',!3.!+9&&'967.7!3S!)6S!+%);.+D!;'**.6,+D!'&!',-.&!,.G,/!N-.!F16)4!
7.41*1,.&!;)6!'%,1'6)44S!3.!,.&*16),.7!:1,-!)!+.*1;'4'6!)67!*9+,!3.!'6!)!416.!3S!1,+.4F/
3.# P44!2)&1)34.!)67!.+;)%.!+.C9.6;.+!:144!3.!16,.&%&.,.7!:1,-16!,-.!-.&.!7';9*.6,/
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Example 4.4.
1 <?php
2 $bgcolor="darkblue";
$tablecolor = "yellow";
3 print <<< MY_BOUNDARY
4 <html><head><title>heredoc</title></head>
5 <body bgcolor="$bgcolor">
6 <table border="1" bgcolor=$tablecolor>
<tr><th>Author</th<th>Book</th></tr>
<tr>
<td>Marcel Proust</td>
<td>Remembrance of Things Past</td>
</tr>
<tr>
<td>Charles Dickens</td>
<td>Tale of Two Cities</td>
</tr>
</table>

7';9*.6,/!N-.&.!;)6!3.!6'!+%);.+!+9&&'96716(!,-.!,.&*16),'&/!N-.!+.*1;'4'6!
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Figure 4.5. Here document output.

!
Escape Sequences
Escape sequences consist of a backslash followed by a single character. When enclosed in double quotes, the backslash
causes the interpretation of the next character to “escape” from its normal ASCII code and to represent something else
(see Table 4.1). To display the escape sequences in your browser, the HTML <pre> tag can be used (see Example
4.5); otherwise, the escape sequences placed within your PHP script will not be interpreted.
Table 4.1. Escape Sequences
Escape#Sequence What#It#Represents
\'

J16(4.!C9',),1'6!*)&M
\"

]'934.!C9',),1'6
\t

N)3
\n

^.:416.
\r

R.,9&6_416.!F..7

</b>
</body>
</html>
Explanation
" V.;)9+.!,-1+!F14.!:144!3.!71+%4)S.7!16!)!3&':+.&!:167':D!,-.!$N\Z!
<pre>
!,)(+!)&.!9+.7!
,'!&.,)16!+%);.+!)67!,)3+/!5F!S'9!&96!#$#!),!,-.!;'**)67!416.D!,-.!.+;)%.!+.C9.6;.+!:144!
3.!16,.&%&.,.7/
0 N-.!#$#!%&'(&)*!+,)&,+!-.&.!:1,-!1,+!'%.616(!,)(/
A N-.!.+;)%.!+.C9.6;.+!*9+,!3.!.6;4'+.7!16!7'934.!C9',.+/!N-.!+.C9.6;.+!F'&!,)3!`
\t
a!
)67!6.:416.!`
\n
a!;-)&);,.&+!%&'79;.!,)3+!)67!6.:416.+/!5F!)!3);M+4)+-!1+!%&.%.67.7!
:1,-!)6',-.&!3);M+4)+-D!,-.6!,-.!3);M+4)+-!1+!,&.),.7!)+!)!41,.&)4/
H 56!,-1+!.G)*%4.D!3S!%&.;.716(!)6!';,)4!'&!-.G)7.;1*)4!69*3.&!:1,-!)!3);M+4)+-D!1,+!
PJb55!.C912)4.6,!1+!71+%4)S.7/
I 5F!)!+,&16(!1+!.6;4'+.7!16!+16(4.!C9',.+D!.+;)%.!+.C9.6;.+!)&.!1(6'&.7/!J..!,-.!'9,%9,!16!
T1(9&.!H/K/
!
Figure 4.6. Escape sequences and the <pre> tag.
!
!

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Figure 4.7. Escape sequences at the command line.
!
!

“PHP and MySQL Integration).
The gettype() Function
The gettype() built-in function returns a string to identify the data type of its argument. The argument might be a
variable, string, keyword, and so on. You can use the gettype() function to check whether or not a variable has been
defined because if there is no value associated with the variable, the gettype() function returns NULL (see Figure
4.9).
Figure 4.9. PHP data types. Output from Example 4.7.

!
Strings returned from the gettype() function include the following:
"boolean" (since PHP 4)
"integer"
"double" (for historical reasons "double" is returned in case of a float, and not simply "float")
"string"
"array"
"object"
"resource" (since PHP 4)
"NULL" (since PHP 4)
Format
string gettype ( mixed var )
!
Examples:
$type=gettype(54.6); // Returns "float" print gettype("yes"); // Returns and
prints "string"

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Example 4.7.

// name: "$x", value: true, type: boolean
!
The values assigned to variables can change throughout the run of a program whereas constants, also called literals,
remain fixed.
PHP variables can be assigned different types of data, including:
• Numeric
• String
• Boolean
• Objects
• Arrays
Computer programming languages like C++ and Java require that you specify the type of data you are going to store in
a variable when you declare it. For example, if you are going to assign an integer to a variable, you would have to say
something like:
int n = 5;
!
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and if you were assigning a floating-point number:
float x = 44.5;
!
Languages that require that you specify a data type are called “strongly typed” languages. PHP, conversely, is a
dynamically, or loosely typed, language, meaning that you do not have to specify the data type of a variable. In fact,
doing so will produce an error. With PHP you would simply say:
$n = 5; $x = 44.5;
!
and PHP will figure out what type of data is being stored in $n and $x.

4.2.2. Valid Names
Variable names consist of any number of letters (an underscore counts as a letter) and digits. The first letter must be a
letter or an underscore (see Table 4.2). Variable names are case sensitive, so Name, name, and NAme are all different
variable names.


To declare a variable called firstname, you could say:
$first_name="Ellie";
!
You can declare multiple variables on the same line by separating each declaration with a semicolon. For example, you
could say:
$ first_name; $middle_name; $last_name;
!
Double, Single, and Backquotes in Assignment Statements
When assigning a value to a variable, if the value is a string, then the string can be enclosed in either single or double
quotes; if the value is returned from a function, then the function is not enclosed in quotes; and if the value is returned
from a system command (see “Execution Operators” on page 143), then the command is enclosed in backquotes:
$name = "Marko"; // Assign a string $city = 'San Francisco'; // Assign a
string $now = date("m/d/Y"); // Assign output of a function $dirlist = 'ls -l';
// Assign output of a UNIX/Linux system command $dirlist = 'dir /D/L' // Assign
a Windows system command
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!
Example 4.8.
<html>
<head><title>Variables</title></head>
<body bgcolor="lightblue">
<font face = "arial" size='+1'>
<?php
1 $name="Joe Shmoe";
2 $age=25.4;
3 $now=date("m/d/Y");
4 $nothing;
5 echo "$name is $age years old.<br />";
6 echo '$nothing contains the value of ', gettype($nothing),

*9+,!3.!)!+,&16(!2)49.D!)67!)&.!.6;4'+.7!16!C9',.+/
H N-.!2)&1)34.!
$nothing
!1+!6',!)++1(6.7!)6!161,1)4!2)49.E!1,!:144!-)2.!,-.!2)49.!
NULL
/
I N-.!+,&16(!1+!.6;4'+.7!16!7'934.!C9',.+/!N-.!F4'),16(U%'16,!2)49.!'F!
$age
!1+!.2)49),.7!
:1,-16!,-.!+,&16(/
K N-.!
gettype()
!F96;,1'6!,.44+!9+!,-),!,-.!,S%.!'F!
$nothing
!1+!
NULL
E!,-),!1+D!1,!-)+!6'!2)49./
? N-.!'9,%9,!'F!,-.!#$#!3914,U16!
date()
!F96;,1'6!:)+!)++1(6.7!,'!
$now
!)67!1+!%&16,.7!`+..!
T1(9&.!H/"@a/
!

$month
D!,'!3.!
71+%4)S.7!16!1,+!6),9&)4!F'&*),!`+..!T1(9&.!H/""a/
!

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