Php

1
Chapter 26 - PHP
Outline
26.1 Introduction
26.2 PHP
26.3 String Processing and Regular Expressions
26.4 Viewing Client/Server Environment Variables
26.5 Form Processing and Business Logic
26.6 Verifying a Username and Password
26.7 Connecting to a Database
26.8 Cookies
26.9 Dynamic Content in PHP
26.10 Operator Precedence
26.11 Web Resources

© 2003 Prentice Hall, Inc. All rights reserved.

2
Objectives

In this chapter, you will learn:
– To understand PHP data types, operators, arrays and control
structures.
– To understand string processing and regular expressions in
PHP.
– To construct programs that process form data.
– To be able to read and write client data using cookies.
– To construct programs that interact with MySQL databases.


3
26.1 Introduction

• PHP
– PHP: Hypertext Preprocessor
– Originally called “Personal Home Page Tools”
– Popular server-side scripting technology
– Open-source
• Anyone may view, modify and redistribute source code
• Supported freely by community
– Platform independent


4
26.2 PHP

• Basic application
– Scripting delimiters
• <? php ?>
• Must enclose all script code
– Variables preceded by $ symbol
• Case-sensitive
– End statements with semicolon
– Comments
• // for single line
• /* */ for multiline
– Filenames end with .php by convention


1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
5
2 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
Outline
3
4 
5  first.php
6 Scripting delimiters (1 of 1)
7 <?php
8 $name = "LunaTic"; // declaration
9 ?> Declare variable $name
10
11 <html xmlns = "http://www.w3.org/1999/xhtml">
12 <head>
13 <title>A simple PHP document</title>Single-line comment
14 </head>
15
16 <body style = "font-size: 2em">
17 <p>
18 <strong>
19
20 
21 Welcome to PHP, <?php print( "$name" ); ?>!
22 </strong>
23 </p>
24 </body>
Function print outputs the value of variable
25 </html>
$name

© 2003 Prentice Hall, Inc.
All rights reserved.

6
26.2 PHP
Fig. 26.1 Simple PHP program.


7
26.2 PHP

• Variables
– Can have different types at different times
– Variable names inside strings replaced by their value
– Type conversions
• settype function
• Type casting
– Concatenation operator
• . (period)
• Combine strings


8
26.2 PHP

Data type Description
int, integer Whole numbers (i.e., numbers without a decimal point).
float, double Real numbers (i.e., numbers containing a decimal point).
string Text enclosed in either single ('') or double ("") quotes.
bool, Boolean True or false.
array Group of elements of the same type.
object Group of associated data and methods.
Resource An external data source.
NULL No value.
Fig. 26.2 PHP data types.


1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
9
2 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> Outline
3
4 
5  data.php
6 (1 of 3)
8 <head>
9 <title>PHP data types</title>
10 </head>
11
12 <body>
13
14 <?php Assign a string to variable
15 $testString
16 // declare a string, double and integer
17 $testString = "3.5 seconds";
18 $testDouble = 79.2;
Assign a double to variable
Assign an integer to variable
$testDouble
19 $testInteger = 12;
$testInteger
20 ?>
21

22 
10
23 <?php print( $testString ); ?> is a string.<br />
Outline
24 <?php print( $testDouble ); ?> is a double.<br />
25 <?php print( $testInteger ); ?> is an integer.<br />
26 data.php
27 <br /> Print each variable’s (2 of 3)
value
28 Now, converting to other types:<br />
29 <?php
30
31 // call function settype to convert variable
32 // testString to different data types
33 print( "$testString" );
34 settype( $testString, "double" );
35 print( " as a double is $testString <br />" );
36 print( "$testString" );
37 settype( $testString, "integer" );
38 print( " as an integer is $testString <br />" );
39 settype( $testString, "string" );
40 Call function settype
print( "Converting back to a string results in to
41 $testString <br /><br function settypetype
Call />" ); the data to
convert of
42 variable $testString to a
convert the data type of
43 $data = "98.6 degrees"; double.
variable $testString to an
integer.
Convert variable $testString
back to a string

44
11
45 // use type casting to cast variables to a
Outline
46 // different type
47 print( "Now using type casting instead: <br />
48 As a string - " . (string) $data . data.php
49 "<br />As a double - " . (double) $data . (3 of 3)
50 "<br />As an integer - " . (integer) $data );
51 ?>
Use type casting to cast variable
52 </body>
$data to different types
53 </html>


12
26.2 PHP
Fig. 26.3 Type conversion.


13
26.2 PHP

• Arithmetic operators
– Assignment operators
• Syntactical shortcuts
• Before being assigned values, variables have value undef
• Constants
– Named values
– define function


14
3
4 
5  operators.php
6 (1 of 3)
8 <head>
9 <title>Using arithmetic operators</title>
10 </head>
11
12 <body>
13 <?php
14 $a = 5; Define constant VALUE.
15 print( "The value of variable a is $a <br />" );
16
17 // define constant VALUE
Add constant VALUE to variable $a.
18 define( "VALUE", 5 );
19
20 // add constant VALUE to variable $a
21 $a = $a + VALUE;
22 print( "Variable a after adding constant VALUE
23 is $a <br />" );
24

25 // multiply variable $a by 2
15
26 $a *= 2;
Multiply variable $a by two using the Outline
27 print( "Multiplying variable a by 2 yields $a <br />" );
multiplication assignment operator *=.
28
29 // test if variable $a is less than 50 operators.php
30 if ( $a < 50 )
Print if variable $a is lesswhether .variable $a is less than3)
Test than 50
(2 of
50

31 print( "Variable a is less than 50 <br />" );
32
33 // add 40 to variable $a
34
Add 40 to variable $a using the addition assignment
$a += 40;
35
operator +=.
print( "Variable a after adding 40 is $a <br />" );
36
37 // test if variable $a is 50 or less
38 if ( $a < 51 )
39 print( "Variable a is still 50 or less<br />" );
40
41 // test if variable $a is between 50 and 100, inclusive
42 elseif ( $a < 101 )
43 print( "Variable a is now between 50 and 100,
44 inclusive<br />" );
45 else
46 print( "Variable a is now greater than 100
47 <br />" );
48


49 // print an uninitialized variable
16
50 print( "Using a variable before initializing:
Outline
51 $nothing <br />" );
52
53 // add constant VALUE to an uninitialized variable operators.php
54 $test = $num + VALUE; (3 of 3)
55 print( "An uninitialized variable plus constant
56 VALUE yields $test <br />" );
57 Print an uninitializedVALUE to ($nothing).
Add constant variable an uninitialized
58 // add a string to an integer
variable.
59 $str = "3 dollars";
60 $a += $str;
61 print( "Adding a string to variable a yields $a
62 <br />" );
63 ?>
64 </body>
Add a string to an integer.
65 </html>


17
26.2 PHP
Fig. 26.4 Using PHP’s arithmetic operators.


18
26.2 PHP

• Keywords
– Reserved for language features
– if…elseif…else
• Arrays
– Group of related data
• Elements
– Name plus braces and index
• Indices start at zero
– count function
– array function


19
26.2 PHP

• Arrays, cont.
– Built-in iterators
• Maintain pointer to element currently referenced
• reset
• key
• next
• foreach loops


20
26.2 PHP

PHP keywords
and do for include require true
break else foreach list return var
case elseif function new static virtual
class extends global not switch xor
continue false if or this while
default
Fig. 26.5 PHP keywords.


21
3
4 
5  arrays.php
6 (1 of 3)
8 <head>
9 <title>Array manipulation</title>
10 </head>
11
12 <body>
13 <?php Create the array $first by assigning a value
14 to an array element.
15 // create array first
16 print( "<strong>Creating the first array</strong>
17 <br />" );
18 $first[ 0 ] = "zero";
19 $first[ 1 ] = Assign
"one"; a value to the array, omitting the index.
20 $first[ 2 ] = Appends a Use a for loop to print outthe array.
"two"; new element to the end of each element’s index and value.
21 $first[] = "three"; Function count returns the total number of elements in the
22 array.
23 // print each element’s index and value
24 for ( $i = 0; $i < count( $first ); $i++ )
25 print( "Element $i is $first[$i] <br />" );

26
22
27 print( "<br /><strong>Creating the second array
Outline
Call function array to create an array that contains
28 </strong><br />" );
29 the arguments passed to it. Store the array in variable
30 // call function array to create array second .
$second arrays.php
31 $second = array( "zero", "one", "two", "three" ); (2 of 3)
32 for ( $i = 0; $i < count( $second ); $i++ )
33 print( "Element $i is $second[$i] <br />" );
34
35 print( "<br /><strong>Creating the third array
36 </strong><br />" );
37
38 // assign values to non-numerical indices
39 $third[ "ArtTic" ] = 21;
Assign values to non-numerical indices
40 $third[ "LunaTic" ] = 18;
in array $third.
41 $third[ "GalAnt" ] = 23; Function reset sets the internal pointer to the
42
first element of the array.
43 // iterate through the array elements and print each
44 // element’s name and value
45 for ( reset( $third ); $element = key( $third );
46 next( $third ) )
47 print( "$element is $third[$element] <br />" );
48 Function key returns the index of the element which
the internal pointer references.
Function next moves the internal pointer to the next
element.

49 print( "<br /><strong>Creating the fourth array
23
50 </strong><br />" );
Outline
51
52 // call function array to create array fourth using
53 // string indices arrays.php
54 $fourth = array( (3 of 3)
55 "January" => "first", "February" => "second",
56 "March" => "third", "April" => "fourth",
57 "May" => "fifth", Operator =>=> used in function array to assign each
"June" is "sixth",
58 "July" => "seventh", "August" string index. The value to the left of the
element a => "eighth",
59 "September" => "ninth", operator is the array index, and the value to the right is
"October" => "tenth",
60 "November" => the element’s value.
"eleventh","December" => "twelfth"
61 );
62
63 // print each element’s name and value
64 foreach ( $fourth as $element => $value )
65 print( "$element is the $value month <br />" );
66 ?>
67 </body>
68 </html>


24
26.2 PHP
Fig. 26.6 Array manipulation.


25
26.3 String Processing and Regular
Expressions
• String processing
– Equality and comparison two important operations
– strcmp function
• Returns –1 if string 1 < string 2
• Returns 0 if string 1 = string 2
• Returns 1 if string 1 > string 2
– Relational operators


26
2 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
Outline
3
4 
5  compare.php
6 (1 of 2)
8 <head>
9 <title>String Comparison</title>
10 </head>
11
12 <body>
13 <?php
Use a for loop to iterate through each array element.
14
15 // create array fruits
16 $fruits = array( "apple", "orange", "banana" );
Function strcmp compares two strings. If the first string
17
alphabetically precedes the second, then –1 is returned. If
18 // iterate through each array element
19
the strings are equal, 0 is returned. If the first string
for ( $i = 0; $i < count( $fruits ); $i++ ) {
20
alphabetically follows the second, then 1 is returned.
21 // call function strcmp to compare the array element
22 // to string "banana"
23 if ( strcmp( $fruits[ $i ], "banana" ) < 0 )
24 print( $fruits[ $i ]." is less than banana " );

25 elseif ( strcmp( $fruits[ $i ], "banana" ) > 0 )
27
26 print( $fruits[ $i ].
Outline
27 " is greater than banana " );
28 else
29 print( $fruits[ $i ]." is Use relational operators
equal to banana " ); to compare each array
compare.php
30 element to string “apple”. (2 of 2)
31 // use relational operators to compare each element
32 // to string "apple"
33 if ( $fruits[ $i ] < "apple" )
34 print( "and less than apple! <br />" );
35 elseif ( $fruits[ $i ] > "apple" )
36 print( "and greater than apple! <br />" );
37 elseif ( $fruits[ $i ] == "apple" )
38 print( "and equal to apple! <br />" );
39
40 }
41 ?>
42 </body>
43 </html>


28
Expressions
Fig. 26.7 Using the string comparison operators.


29
Expressions
• Regular expressions
– Pattern matching templates
– ereg function
• POSIX
– preg_match function
• Perl
– ereg_replace function

• Building regular expressions
– Metacharacters
• $, ., ^
– Brackets [ ]


30
3
4 
5  expression.php
6 (1 of 3)
8 <head>
9 <title>Regular expressions</title>
10 </head>
11
12 <body>
13 <?php Function ereg searches for the literal
14 $search = "Now is the characters Now inside variable $search.
time";
15 print( "Test string is: '$search'<br /><br />" );
16
17 // call function ereg to search for pattern 'Now'
18 // in variable search
19 if ( ereg( "Now", $search ) )
20 print( "String 'Now' was found.<br />" );
21

22 // search for pattern 'Now' in the beginning of
31
23 // the string
Outline
24 if ( ereg( "^Now", $search ) )
The dollar sign special character ($) search for the
25 print( "String 'Now' found at beginning
pattern Now at the end of the string.
26 of the line.<br />" ); special character (^) matches the
The caret expression.php
27 beginning of a string. Function ereg searches the (2 of 3)
28 // beginning of theend of the pattern Now .
search for pattern 'Now' at the string for string
29 if ( ereg( "Now$", $search ) )
30 print( "String 'Now' was found at the end
31 of the line.<br />" );
32
33 // search for any word ending in 'ow'
34 if ( ereg( "[[:<:]]([a-zA-Z]*ow)[[:>:]]", $search,
35 $match ) )
36 print( "Word found ending in 'ow': " .
37 $match[ 1 ] . "<br />" );
38
The expression inside the expressions [[:<:]] and ,
The special bracket parentheses, [a-zA-Z]*ow
39 // search for any words beginning with 't'
matches anypatternending beginning and end matched
Placing a word in the in ow. The quantifier * word,
[[:>:]] match parentheses stores the of a
40 print( "Words beginning with 't' found: ");
matches thethe array that is specified in the third argument
string in preceding pattern 0 or more times.
respectively.
41
42
to function ereg.
while ( eregi( "[[:<:]](t[[:alpha:]]+)[[:>:]]",
43 $search, $match ) ) {
44 print( $match[ 1 ] . " " );
The pattern used in this example, [[:<:]]
45
(t[[:alpha:]]+)[[:>:]], matches any word
The while beginning with find each occurrence of a
loop is used to the
Function eregi is used to specifycharacter t followed by one or more
case insensitive
word in thecharacters. Character class [[:alpha:]] recognizes
string beginning with t.
pattern matches.
any alphabetic character. © 2003 Prentice Hall, Inc.

46 // remove the first occurrence of a word beginning
32
47 // with 't' to find other instances in the string
Outline
48 $search = ereg_replace( $match[ 1 ], "", $search );
49 }
50 expression.php
After printing a match of a word beginning with t, function
51 print( "<br />" ); (3 of 3)
ereg_replace is called to remove the word from the string.
52 ?> This is necessary be because to find multiple instances of a
53 </body> given pattern, the first matched instance must first be removed.
54 </html>
Function ereg_replace takes three arguments: the pattern to
match, a string to replace the matched string and the string to
search.


33
Expressions
Fig. 26.8 Regular expressions in PHP.


34
Expressions

Quantifier Matches
{n} Exactly n times.
{m,n} Between m and n times inclusive.
{n,} n or more times.
+ One or more times (same as {1,}).
* Zero or more times (same as {0,}).
? Zero or one time (same as {0,1}).
Fig. 26.9 Some PHP quantifiers.


35
Expressions

Character class Description
alnum Alphanumeric characters (i.e., letters [a-zA-Z] or digits [0-9]).
alpha Word characters (i.e., letters [a-zA-Z]).
digit Digits.
space Whitespace.
lower Lowercase letters.
upper Uppercase letters.
Fig. 26.10 Some PHP character classes.


36
26.4 Viewing Client/Server Environment
Variables
• Environment variables
– Provide information about execution environment
• Type of Web browser
• Type of server
• Details of HTTP connection
– Stored as array in PHP
• $_ENV


37
Variables
Variable name Description
$_SERVER Data about the currently running server.
$_ENV Data about the client’s environment.
$_GET Data posted to the server by the get method.
$_POST Data posted to the server by the post method.
$_COOKIE Data contained in cookies on the client’s computer.
$GLOBALS Array containing all global variables.
Fig. 26.11 Some useful global arrays.


38
Outline
3
4 
5  env.php
6 (1 of 1)
8 <head>
9 <title>Environment Variables</title>
10 </head>
11
12 <body>
13 <table border = "0" cellpadding = "2" cellspacing = "0"
14 width = "100%">
15 <?php
16
17 // print the key and value for each element
18 // in the $_ENV array
19 foreach ( $_ENV as $key => $value )
20 print( "<tr><td bgcolor = "#11bbff">
21 The foreach loop
<strong>$key</strong></td> is used to print out the keys and
22 <td>$value</td></tr>" each element in the $_ENV array.
values for );
23 ?> PHP stores environment variables and their values in
24 </table> the $_ENV array.
25 </body>
26 </html>

39
Variables
Fig. 26.12 Displaying environment variables.


40

• Form processing
– action property
• Where to send form data
– method property
• post
– Each element has unique name


41
3
4 
5  form.html
6 (1 of 4)
8 <head>
9 <title>Sample form to take user input in XHTML</title>
10 </head>
11
12 <body>
13 The action attribute of the form element
14 <h1>This is indicates that when the user clicks Register, the
a sample registration form.</h1>
15 Please fill in all fields and click Register. posted to form.php.
form data will be
16
17 
18 <form method = "post" action = "form.php">
19 <img src = "images/user.gif" alt = "User" /><br />
20 <span style = "color: blue">
21 Please fill out the fields below.<br />
22 </span>
23

24 
42
25
A unique name (e.g., email) is assigned to each Outline
<img src = "images/fname.gif" alt = "First Name" />
26 <input type = "text" name = "fname" /><br />
of the form’s input fields. When Register is
27
clicked, each field’s name and value are sent to
28 <img src = "images/lname.gif" alt = "Last Name" />
the Web server. form.html
29 <input type = "text" name = "lname" /><br /> (2 of 4)
30
31 <img src = "images/email.gif" alt = "Email" />
32 <input type = "text" name = "email" /><br />
33
34 <img src = "images/phone.gif" alt = "Phone" />
35 <input type = "text" name = "phone" /><br />
36
37 <span style = "font-size: 10pt">
38 Must be in the form (555)555-5555</span>
39 <br /><br />
40
41 <img src = "images/downloads.gif"
42 alt = "Publications" /><br />
43
45 Which book would you like information about?
46 </span><br />
47

48 
43
49 <select name = "book">
Outline
50 <option>Internet and WWW How to Program 3e</option>
51 <option>C++ How to Program 4e</option>
52 <option>Java How to Program 5e</option> form.html
53 <option>XML How to Program 1e</option> (3 of 4)
54 </select>
55 <br /><br />
56
57 <img src = "images/os.gif" alt = "Operating System" />
58 <br /><span style = "color: blue">
59 Which operating system are you currently using?
60 <br /></span>
61
62 
63 <input type = "radio" name = "os" value = "Windows XP"
64 checked = "checked" />
65 Windows XP
66
67 <input type = "radio" name = "os" value =
68 "Windows 2000" />
69 Windows 2000
70
71 <input type = "radio" name = "os" value =
72 "Windows 98" />
73 Windows 98<br />

74
44
75 <input type = "radio" name = "os" value = "Linux" />
Outline
76 Linux
77
78 <input type = "radio" name = "os" value = "Other" /> form.html
79 Other<br /> (4 of 4)
80
81 
82 <input type = "submit" value = "Register" />
83 </form>
84
85 </body>
86 </html>

45
Fig. 26.13 XHTML form for gathering user input.


46

• Business logic
– Confirm that valid information was entered
– extract function
• Creates variables corresponding to each key-value pair in array
• Easily retrieve all values sent to PHP page
– Regular expressions very helpful
– Do checks on client side where possible
• JavaScript
• Conserves server resources
• Ending a script
– die function
• Remember to close all HTML tags


47
3
4 
5  form.php
6 (1 of 4)
8 <head>
9 <title>Form Validation</title>
10 </head>
11
12 <body style = "font-family: arial,sans-serif">
13 The parentheses in Function ereg must be to determine whether the
the expression is called
followed by The expression ( matchesclosing user is valid.
phone number entered by the
14 <?php three digits ([0-9]{3}), a the opening
15 extract( $_POST parenthesis, parentheses ofliteral hyphen and
); three digits, a a phone number.
16 four additional digits.
17 // determine whether phone number is valid and print
18 // an error message if not
19 if ( !ereg( "^([0-9]{3})[0-9]{3}-[0-9]{4}$",
20 $phone ) ){
21
We access the phone field’s value from
form.html by using variable $phone.

22 print( "<p><span style = "color: red;
48
23 font-size: 2em">
Outline
24 INVALID PHONE NUMBER</span><br />
25 A valid phone number must be in the form
26 <strong>(555)555-5555</strong><br /> form.php
27 <span style = "color: blue"> (2 of 4)
28 Click the Back button, enter a valid phone
Function die terminates script execution
29 number and resubmit.<br /><br />
30 Thank You.</span></p></body></html>" );
31
32 die(); // terminate script execution
33 }
34 ?>
35
36 <p>Hi
38 <strong>
39 <?php print( "$fname" ); ?>
40 </strong>
41 </span>.
42 Thank you for completing the survey.<br />
43


44 You have been added to the
49
Outline
46 <strong>
47 <?php print( "$book " ); ?>
48 </strong> form.php
49 </span> (3 of 4)
50 mailing list.
51 </p>
52 <strong>The following information has been saved
53 in our database:</strong><br />
54
55 <table border = "0" cellpadding = "0" cellspacing = "10">
56 <tr>
57 <td bgcolor = "#ffffaa">Name </td>
58 <td bgcolor = "#ffffbb">Email</td>
59 <td bgcolor = "#ffffcc">Phone</td>
60 <td bgcolor = "#ffffdd">OS</td>
61 </tr>
62
63 <tr>
64 <?php
65


66 // print each form field’s value
50
67 print( "<td>$fname $lname</td>
Outline
68 <td>$email</td>
69 <td>$phone</td>
70 <td>$os</td>" ); form.php
71 ?> (4 of 4)
72 </tr>
73 </table>
74
75 <br /><br /><br />
76 <div style = "font-size: 10pt; text-align: center">
77 This is only a sample form.
78 You have not been added to a mailing list.
79 </div>
80 </body>
81 </html>


51
Fig. 26.14 Obtaining user input through forms.


52

• Private website
– Only accessible to certain individuals
– Encrypt username and password data when sending, storing
and retrieving for increased security
• Implementing password checking
– Login information stored in file
• fopen function
• Read, write, append modes
– Store data using fputs
• n newline character
– Close files when done
• fclose function


53

• Implementing password checking, cont.
– Trim newline character
• chop function
– Split string into substrings given a certain delimiter
• split function
– If username/password match list, allow access


54
Outline
3
4 
5  password.html
6 (1 of 4)
8 <head>
9 <title>Verifying a username and a password.</title>
10
11 <style type = "text/css">
12 td { background-color: #DDDDDD }
13 </style>
14 </head>
15
16 <body style = "font-family: arial">
17 <p style = "font-size: 13pt">
18 Type in your username and password below.
19 <br />
20 <span style = "color: #0000FF; font-size: 10pt;
21 font-weight: bold">
22 Note that password will be sent as plain text
23 </span>
24 </p>
25

26 
55
27 <form action = "password.php" method = "post">
Outline
28 <br />
29 Form data is posted to password.php.
30 <table border = "0" cellspacing = "0" password.html
31 style = "height: 90px; width: 123px; (2 of 4)
32 font-size: 10pt" cellpadding = "0">
33
34 <tr>
35 <td colspan = "3">
36 <strong>Username:</strong>
37 </td>
38 </tr>
39
40 <tr>
42 <input size = "40" name = "USERNAME"
43 style = "height: 22px; width: 115px" />
44 </td>
45 </tr>
46

47 <tr>
56
Outline
49 <strong>Password:</strong>
50 </td>
51 </tr> password.html
52 (3 of 4)
53 <tr>
55 <input size = "40" name = "PASSWORD"
56 style = "height: 22px; width: 115px"
57 type = "password" />
58 <br/></td>
59 </tr>
60
61 <tr>
63 <input type = "submit" name = "Enter"
64 value = "Enter" style = "height: 23px;
65 width: 47px" />
66 </td>
68 <input type = "submit" name = "NewUser"
69 value = "New User"
70 style = "height: 23px" />
71 </td>


72 </tr>
57
73 </table>
Outline
74 </form>
75 </body>
76 </html> password.html
(4 of 4)


58
Fig. 26.15 XHTML form for obtaining a username and password.


59
3
4 
5  password.php
6 (1 of 7)
8 <head> Variable names, when preceded by the logical
9 <?php negation operator (!), return true if they are empty
10 extract( $_POST ); or set to 0. This checks if a user has submitted a form
11 without specifying a username or password.
12 // check if user has left USERNAME or PASSWORD field blank
13 if ( !$USERNAME || !$PASSWORD ) { Function fieldsBlank is called if the user has
14
Function isset tests whether thenotify the user
submitted an incomplete form to user has
fieldsBlank();
15
pressed form fields must be completed. that a
that all the New User button, indicating
die();
16 }
new user must be added.
17
18 To add a
// check if the New User button was clicked new user, we open the file
19 if ( isset( $NewUser ) ) { password.txt in append mode and assign the
20 file handle that is returned to variable $file.
21 // open password.txt for writing using append mode
22 if ( !( $file = fopen( "password.txt",
23 "a" ) ) ) {
24

25 // print error message and terminate script
60
26 // execution if file cannot be opened
Outline
27 print( "<title>Error</title></head><body>
28 Could not open password file
29 </body></html>" ); password.php
30 die(); Print an error message and terminate script execution
(2 of 7)
31 } if the file cannot be opened.
32
33 // write username and password to file and
34 // call function userAdded
35 fputs( $file, "$USERNAME,$PASSWORDn" );
36 userAdded( $USERNAME );
37 }
38 else { Function userAdded is called to print a message to the
Function fputs writes the name and password to the
39 user to indicate that the username and password were
text file..
40 // if a new user added to the file.
is not being added, open file
41 // for reading
42 if ( !( $file = fopen( "password.txt",
43 "r" ) ) ) {
44 print( "<title>Error</title></head>
45 <body>Could not open password file
46 </body></html>" );
47 die();
48 }
49


50 $userVerified = 0;
61
51
Outline
52
Before entering the
// read each line in file and check usernamewhile loop, variable
53 Function fgets reads a lineset to 0. text file.
// and password $userVerified is from the
54 while ( !feof( $file result !$userVerified variable $line.
The ) && is assigned to ) { password.php
55 (3 of 7)
56 // read line from file
57
The while loop executes as long as the there are more
$line = fgets( Function chop
$file, 255 ); removes the newline character
58
lines in the file to read end of the line.
from the and variable $userVerified is
59
still 0 or empty. is called to separate the string at the
Function split
// remove newline character from end of line
specified delimiter (in this case, a comma). The
60 $line = chop( $line );
resulting array usernamein array $fielduser is tested
The is stored entered by the .
61
against the one returned in the text file (stored
62 // split username and password
in the first element of the array). If they match,
63 $field = split( ",", $line, 2 );
variable $userVerified is set to 1.
64
65 // verify username
66 if ( $USERNAME == $field[ 0 ] ) {
67 $userVerified = 1;
68
69 If function
// call function checkPassword to verify checkPassword returns true, function
70 // user’s password accessGranted is called to notify the client that
71 permission
if ( checkPassword( $PASSWORD, $field ) has been granted. Otherwise, function
72 == true ) wrongPassword is called.
73 accessGranted( $USERNAME );
74 else
Function checkPassword is called to verify the
75 wrongPassword();
user’s password. Variable $PASSWORD and array
$field are passed to the function. © 2003 Prentice Hall, Inc.

76 }
62
77 }
Outline
78 If variable $userVerified has not been set to a
79 // close text value other After 0, function loop has executed, function
file than the while accessDenied is
80 fclose( $file called to notify the client that access has file.
);
fclose is called to close the been password.php
81 denied. (4 of 7)
82 // call function accessDenied if username has
83 // not been verified
Function checkPassword compares the user’s
84 if ( !$userVerified )
password to the password in the file. If they match,
85 accessDenied();
true is returned, whereas false is returned if they
86 }
do not.
87
88 // verify user password and return a boolean
89 function checkPassword( $userpassword, $filedata )
90 {
91 if ( $userpassword == $filedata[ 1 ] )
92 return true;
93 else
94 return false;
95 }
96


97 // print a message indicating the user has been added
63
98 function userAdded( $name )
Outline
99 {
100 print( "<title>Thank You</title></head>
101 Function arial;
<body style = "font-family: userAdded prints a message to the password.php
102 font-size: 1em; client indicating that the user has been added.
color: blue"> (5 of 7)
103 <strong>You have been added
104 to the user list, $name. Function accessGranted prints a
105 <br />Enjoy the site.</strong>"message to the client indicating that
);
106 } permission has been granted.
107
108 // print a message indicating permission
109 // has been granted
110 function accessGranted( $name )
111 {
112 print( "<title>Thank You</title></head>
113 <body style = "font-family: arial;
114 font-size: 1em; color: blue">
115 <strong>Permission has been
116 granted, $name. <br />
117 Enjoy the site.</strong>" );
118 }
119


120 // print a message indicating password is invalid
64
121 function wrongPassword()
Outline
122 {
Function wrongPassword prints a message to the
123 print( "<title>Access Denied</title></head>
client indicating that the password is invalid.
124 <body style = "font-family: arial; password.php
125 font-size: 1em; color: red"> (6 of 7)
126 <strong>You entered an invalid
127 password.<br />Access has
128 been denied.</strong>" );
129 }
130
131 // print a message indicating access has been denied
132 function accessDenied()
133 {
134 print( "<title>Access Denied</title></head>
135 <body style = "font-family: arial;
136 font-size: 1em; color: red">
137 <strong>
138 You were denied access to this server.
139 <br /></strong>" ); Function accessDenied prints a message to the
140 } client indicating that access has been denied.
141


142 // print a message indicating that fields
65
143 // have been left blank
Function fieldsBlank prints a message toOutline the
144 function fieldsBlank()
client indicating that all form fields have not been
145 {
completed.
146 print( "<title>Access Denied</title></head> password.php
147 <body style = "font-family: arial; (7 of 7)
148 font-size: 1em; color: red">
149 <strong>
150 Please fill in all form fields.
151 <br /></strong>" );
152 }
153 ?>
154 </body>
155 </html>


66
Fig. 26.16 Verifying a username and password.


1 account1,password1
67
2 account2,password2 Outline
5 account5,password5 password.txt
6 account6,password6 (1 of 1)


68

• Databases
– Store and maintain data
– MySQL is a free database product
– PHP supports many database operations
• Access databases from Web pages


69
Outline
3
4 
5  data.html
6 (1 of 2)
8 <head>
9 <title>Sample Database Query</title>
10 </head>
11
12 <body style = "background-color: #F0E68C">
13 <h2 style = "font-family: arial color: blue">
14 Querying a MySQL database.
15 </h2>
16
17 <form method = "post" action = "database.php">
18 <p>Select a field to display:
19
20 
21

22 <select name = "select">
70
23 <option selected = "selected">*</option>
Outline
24 <option>ID</option>
25 <option>Title</option> Select box containing options for a SELECT
26 <option>Category</option> query. data.html
27 <option>ISBN</option> (2 of 2)
28 </select>
29 </p>
30
31 <input type = "submit" value = "Send Query"
32 style = "background-color: blue;
33 color: yellow; font-weight: bold" />
34 </form>
35 </body>
36 </html>


71
Fig. 26.18 Form to query a MySQL database.


72

• Interacting with databases
– SQL
• Structured Query Language
• Used to manipulate databases
– Several useful functions
• mysql_connect
• mysql_select_db
• mysql_query
• mysql_error
• mysql_fetch_row
• mysql_close


73
3
4 
5  database.php
6  (1 of 3)
7
9 <head>
10 <title>Search Results</title>
11 </head>
12
13 <body style = "font-family: arial, sans-serif"
14 style = "background-color: #F0E68C">
15 <?php Build the select query and assign the
16 string to variable $query.
17 extract( $_POST ); Function mysql_connect returns a database
18 handle which represents PHP’s connection to a
19 // build SELECT query database. If this connection is not made, function
20 $query = "SELECT " . $select . " die is called to terminate script execution.
FROM Books";
21
22 // Connect to MySQL
23 if ( !( $database = mysql_connect( "localhost",
24 "httpd", "" ) ) )
25 die( "Could not connect to database" );

26
74
27 // open Products database
Outline
28 Function )
if ( !mysql_select_db( "Products", $database ) mysql_query returns an object
29 containing the result set of the query, which
die( "Could not open Products database" );
30 we assign to variable $result. database.php
31 // query Products database (2 of 3)
32 if ( !( $result = mysql_query( $query, $database ) ) ) {
Function mysql_select_db is called to specify the
33 print( "Could not execute query! <br />" );
database to be queried.
34 die( mysql_error() );
35 }
36 ?>
37
38 <h3 style = "color: blue">
39 Search Results</h3>
40
41 <table border = "1" cellpadding = "3" cellspacing = "2"
42 style = "background-color: #ADD8E6">
43
44 <?php The for loop iterates through each
45 record in the result set while
46 // fetch each record in result set constructing an XHTML table from
47 for ( $counter = 0; the results. Variable $counter is
48 $row = mysql_fetch_row( $result incremented by one for each row
);
49 $counter++ ){ retrieved. Function mysql_fetch_row returns an
50 array containing the elements of each row
in the result set of our query ($result).


51 // build table to display results
75
52 print( "<tr>" );
Outline
53
54 foreach ( $row as $key => $value )
55 print( "<td>$value</td>" ); database.php
56 (3 of 3)
57 print( "</tr>" );
The foreach loop iterates through the
58 }
array containing the elements of each row
59
and prints out each element in an
60 mysql_close( $databaseThe total number of results are printed to the
);
individual table cell.
61 ?> client.
62
63 </table>
64
65 <br />Your search yielded <strong>
66 <?php print( "$counter" ) ?> results.<br /><br /></strong>
67
68 <h5>Please email comments to
69 <a href = "mailto:deitel@deitel.com">
70 Deitel and Associates, Inc.
71 </a>
72 </h5>
73
74 </body>
75 </html>


76
Fig. 26.19 Querying a database and displaying the results.


77
26.8 Cookies

• Cookies
– Store information on client computer
– Track preferences and other information
– Stored as text files on hard drive
– Never store sensitive information, such as credit card
numbers, in a cookie
• Security risk
• Cookies and PHP
– setcookie function
• Name
• Value
• Expiration date


78
3
4 
5  cookies.html
6 (1 of 2)
8 <head>
9 <title>Writing a cookie to the client computer</title>
10 </head>
11
12 <body style = "font-family: arial, sans-serif;
13 background-color: #99CCFF">
14
15 <h2>Click Write Cookie to save your cookie data.</h2>
16

17 <form method = "post" action = "cookies.php"
79
18 style = "font-size: 10pt">
Outline
19 <strong>Name:</strong><br /> Form data is posted to cookies.php.
20 <input type = "text" name = "NAME" /><br />
21 cookies.html
22 <strong>Height:</strong><br /> (2 of 2)
23 <input type = "text" name = "HEIGHT" /><br />
24
25 <strong>Favorite Color:</strong><br />
26 <input type = "text" name = "COLOR" /><br />
27
28 <input type = "submit" value = "Write Cookie"
29 style = "background-color: #F0E86C; color: navy;
30 font-weight: bold" /></p>
31 </form>
32 </body>
33 </html>


80
26.8 Cookies
Fig. 26.20 Gathering data to be written as a cookie.


1 <?php
81
2 // Fig. 26.21: cookies.php Outline
3 // Program to write a cookie to a client's machine
4
5 extract( $_POST ); cookies.php
6 // write each form field’s value to a cookie and set the (1 of 2)
7 // cookie’s expiration date
8 setcookie( "Name", $NAME, time() + 60 * 60 * 24 * 5 );
9 setcookie( "Height", $HEIGHT, time() + 60 * 60 * 24 * 5 );
10 setcookie( "Color", $COLOR, time() + 60 * 60 * 24 * 5 );
11 ?> Function setcookie takes the name of the
12 cookie to be set as the first argument,
13 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" the value to be stored in the
followed by
14 cookie. The optional third argument specifies
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
15 the expiration date of the cookie.
17 <head>
18 <title>Cookie Saved</title>
19 </head>
20
21 <body style = "font-family: arial, sans-serif">
22 <p>The cookie has been set with the following data:</p>
23


24 
82
25 Each
<br /><span style = "color: blue">Name:</span> form field’s value is printed to Outline
26 <?php print( $NAME ) ?><br /> confirm the data that has been set as a
27 cookie with the user.
28 <span style = "color: blue">Height:</span> cookies.php
29 <?php print( $HEIGHT ) ?><br /> (2 of 2)
30
31 <span style = "color: blue">Favorite Color:</span>
32
33 <span style = "color: <?php print( "$COLOR">$COLOR" ) ?>
34 </span><br />
35 <p>Click <a href = "readCookies.php">here</a>
36 to read the saved cookie.</p>
37 </body>
38 </html>
Hyperlink to readCookies.php.

83
26.8 Cookies
Fig. 26.21 Writing a cookie to the client.


84
26.8 Cookies

• Reading cookies
– $_COOKIE environment variable
• Array
– foreach loop to access each element
• Split into key and value


85
26.8 Cookies

• Cookie storage
– Internet Explorer
• Stores cookies in Cookies directory
• Text file


86
26.8 Cookies
Fig. 26.22 Cookies directory before a cookie is written.

Fig. 26.23 Cookies directory after a cookie is written.


87
3
4 
5  readCookies.php
6 (1 of 2)
8 <head><title>Read Cookies</title></head>
9
10 <body style = "font-family: arial, sans-serif">
11
12 <p>
13 <strong>
14 The following data is saved in a cookie on your
15 computer.
16 </strong>
17 </p>
18

19 <table border = "5" cellspacing = "0" cellpadding = "10">
88
PHP creates array $_COOKIE which contains all Outline
20 <?php
The foreach loop iterates through the $_COOKIE
21
array and prints thevalues and value of each cookie in
cookie name indexed by their names.
22 // iterate through array $_COOKIE and print
an XHTML table.
23 // name and value of each cookie readCookies.php
24 foreach ( $_COOKIE as $key => $value ) (2 of 2)
25 print( "<tr>
26 <td bgcolor="#F0E68C">$key</td>
27 <td bgcolor="#FFA500">$value</td>
28 </tr>" );
29 ?>
30
31 </table>
32 </body>
33 </html>


89
26.8 Cookies
Fig. 26.24 Displaying the cookie’s content.


90
26.9 Dynamic Content in PHP

• Dynamically alter XHTML content
– Form’s action property set to same page that contains it
– Perform different actions when page is loaded and form is
submitted
• isset variable
– Check for errors
• Write different XHTML when errors encountered
– $$variable syntax
• References variable whose name equals the value of $variable
– If input is valid, make MySQL database calls


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