Programming PHP

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Chapter CHAPTER 9 9 Graphics The Web is more than just text. Images appear in the form of logos, buttons, photographs, charts, advertisements, and icons. Many of these images are static, built with tools such as PhotoShop and never changed. But many are dynamically created— from advertisements for Amazon’s referral program that include your name to Yahoo! Finance’s graphs of stock performance. PHP supports graphics creation with the GD and Imlib2 extensions. In this chapter we’ll show you how to generate images dynamically with PHP, using the GD extension. Embedding an Image in a Page A common misconception is that there is a mixture of text and graphics flowing across a single HTTP request. After all, when you view a page you see a single page containing such a mixture. It is important to understand that a standard web page containing text and graphics is created through a series of HTTP requests from the web browser, each answered by a response from the web server. Each response can contain one and only one type of data, and each image requires a separate HTTP request and web server response. Thus, if you see a page that contains some text and two images, you know that it has taken three HTTP requests and corresponding responses to construct this page. Take this HTML page, for example: 214 Example Page This page contains two images. This is the Title of the Book, eMatter Edition Copyright © 2002 O’Reilly & Associates, Inc. All rights reserved.
The series of requests sent by the web browser for this page looks something like this: GET /page.html HTTP/1.0 GET /image1.jpg HTTP/1.0 GET /image2.jpg HTTP/1.0 The web server sends back a response to each of these requests. The Content-Type headers in these responses look like this: Content-Type: text/html Content-Type: image/jpeg Content-Type: image/jpeg To embed a PHP-generated image in an HTML page, pretend that the PHP script that generates the image is actually the image. Thus, if we have image1.php and image2. php scripts that create images, we can modify the previous HTML to look like this: Example Page This page contains two images. Instead of referring to real images on your web server, the img tags nowrefer to the PHP scripts that generate the images. Furthermore, you can pass variables to these scripts, so instead of having separate scripts to generate the two images, you could write your img tags like this: Then, inside image.php, you can access $_GET['num'] (or $num, ifregister_globals is on) to generate the appropriate image. The GD Extension Before you can start generating images with PHP, you need to check that you actually have image-generation capabilities in your PHP installation. In this chapter we’ll discuss using the GD extension, which allows PHP to use the open source GD graphics library available from http://www.boutell.com/gd/. Load the familiar phpinfo( ) page and look for a section entitled “GD”. You should see something similar to the following. gd GD Support enabled GD Version 2.0 or higher This is the Title of the Book, eMatter Edition Copyright © 2002 O’Reilly & Associates, Inc. All rights reserved. The GD Extension | 215
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Programming PHP
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Programming PHP by Rasmus Lerdorf a
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Colophon Our look is the result of
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Accessing Individual Characters 79
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Concealing PHP Libraries 293 PHP Co
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clarify the explanations, and the p
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There is a web page for this book,
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Chapter 2 CHAPTER 2 Language Basics
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Comments Comments give information
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*/ echo("l=$l m=$m n=$n\n"); ?> Now
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change. Constants are referred to b
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PHP recognizes floating-point numbe
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• The empty string ("") and the s
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Chapter 6 describes classes and obj
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The old value of $black is lost. In
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update_counter( ); update_counter(
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Table 2-3. PHP operators P A Operat
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The division and multiplication ope
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Autoincrement and Autodecrement Ope
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Bitwise Operators The bitwise opera
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something is true. For example, you
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Because all operators are required
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if The if statement checks the trut
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A switch statement is given an expr
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if ($i == 5) break; // breaks out o
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This program adds the numbers from
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loops, and complain if the file bei
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XML Style Because of the advent of
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and other such niceties. Some will
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Chapter 3 CHAPTER 3 Functions A fun
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Typically, functions return some va
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As we discussed in Chapter 2, the e
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Example 3-5. Doubler redux function
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Missing Parameters PHP lets you be
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Anonymous Functions Some PHP functi
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echo "$who was $where"; Kilroy was
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As a special case, you can put a se
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• A padding specifier denoting th
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Boolean values and NULL are not mea
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Changing Case PHP has several funct
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The quote_style and charset argumen
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Query-string encoding The urlencode
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The comparison operators (=) also w
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The Levenshtein algorithm calculate
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The str_repeat( ) function takes a
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print_r($a);Array ( [0] => Fred [1]
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The c in strcspn( ) stands for comp
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These three kinds of patterns can b
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Subpatterns You can use parentheses
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Table 4-8. POSIX anchors Anchor Mat
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Example 4-1. Credit-card validator
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Character Classes Perl-style regula
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Trailing Options Perl-style regular
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A simple use of positive lookahead
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For example: preg_match('/y.*e$/',
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Pass an array of strings as subject
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Quoting for regular expressions The
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Identifying Elements of an Array Yo
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array is almost always a programmer
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Two or more consecutive commas in t
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echo "true!\n"; } if (array_key_exi
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EXTR_PREFIX_SAME, which says that t
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echo "$key is $value\n"; } 0 is spa
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The default argument, if provided,
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you need to answer questions like
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Example 5-3. Sorting arrays (contin
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Here’s how to randomize the order
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Sets Arrays let you implement the b
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Here’s the output from Example 5-
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Terminology Everyobject-oriented la
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You can use variable variables with
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} function set_name ($new_name) { $
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The object created bythe Person con
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Example 6-1. Displaying all declare
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Example 6-2. Object introspection f
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Here are some sample classes and ob
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PHP has two hooks for objects durin
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Example 6-5 shows the file next.php
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the request contains a blank line,
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SERVER_NAME The hostname, DNS alias
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Page 165 and 166: Figure 7-1. The chunkify form and i
Page 167 and 168: Example 7-4. Temperature conversion
Page 169 and 170: Example 7-6. Multiple selection val
Page 171 and 172: Example 7-8. Sticky multivalued che
Page 173 and 174: Files are stored in the server’s
Page 175 and 176: “me@aol” by requiring an at sig
Page 177 and 178: To mark a document as already expir
Page 179 and 180: A third technique for maintaining s
Page 181 and 182: Example 7-10. Preference selection
Page 183 and 184: Session basics To enable sessions f
Page 185 and 186: Custom storage By default, PHP stor
Page 187 and 188: When a session is completed, the de
Page 189 and 190: Chapter 8 CHAPTER 8 Databases PHP h
Page 191 and 192: columns, each of which has a name a
Page 193 and 194: Figure 8-1. The movie page the data
Page 195 and 196: $db = DB::connect($datasource); if
Page 197 and 198: string(4) "1962" ["name"]=> string(
Page 199 and 200: The executeMultiple( ) method takes
Page 201 and 202: echo "$k"; if (is_array($v)) { a_to
Page 203 and 204: Two HTML forms are needed to popula
Page 205 and 206: Example 8-3. Database connection ab
Page 207 and 208: Example 8-4. Backend administration
Page 209 and 210: Example 8-5. Adding a business (con
Page 211 and 212: Example 8-5. Adding a business (con
Page 213: The business listings page is illus
Page 217 and 218: many colors as you need. The latter
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Page 221 and 222: Example 9-4. Adding text to an imag
Page 223 and 224: Example 9-6. Displaying vertical Tr
Page 225 and 226: Example 9-8. Caching dynamic button
Page 227 and 228: You can also take this a step furth
Page 229 and 230: For a signed integer, the leftmost
Page 231 and 232: True Color Color Indexes The color
Page 233 and 234: Chapter 10 CHAPTER 10 PDF Adobe’s
Page 235 and 236: Figure 10-1. Hello world in a PDF d
Page 237 and 238: Type, Content-Disposition, and Cont
Page 239 and 240: Example 10-3. Changing the origin (
Page 241 and 242: Example 10-4. Text alignment within
Page 243 and 244: Example 10-5. Changing text attribu
Page 245 and 246: usr/share/fonts FontAFM LuciduxSans
Page 247 and 248: Adding an image to a PDF document i
Page 249 and 250: Example 10-8. Nonproportional scali
Page 251 and 252: Figure 10-9. A sample path The pdf_
Page 253 and 254: The width and height parameters spe
Page 255 and 256: Example 10-11. Using a template Th
Page 257 and 258: Example 10-12. Using bookmarks and
Page 259 and 260: Example 10-13. Specifying a link (c
Page 261 and 262: Figure 10-16. Closed note The conte
Page 263 and 264: In HTML, you often have an open tag
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Example 11-1. Generating an XML doc
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The end element handler is called w
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If your external entity reference h
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characters outside the target encod
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XML_ERROR_BAD_CHAR_REF XML_ERROR_BI
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Figure 11-2. Book details comment).
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Example 11-10. bookparse.xml (conti
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Example 11-12. News XSL transform
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more information). The xmlrpc exten
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equest, but it doesn’t know how t
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Chapter 12 CHAPTER 12 Security PHP
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These directives ensure that PHP er
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Restrict Filesystem Access to a Spe
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function or PHP’s copy( ) functio
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• Any system call (through functi
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You can globally disable particular
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Chapter 13 CHAPTER 13 Application T
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user.template. It uses the {DESTINA
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{ARTICLE} might be useful, as it wo
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} ob_start('rewrite'); ?> Visit our
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To turn off error reporting entirel
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Example 13-5. Log-rolling error han
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Before you begin optimization, ask
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changes you make to your code as yo
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• Only include or require files t
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MySQL replication Sometimes the dat
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Chapter 14 CHAPTER 14 Extending PHP
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examples, and you are strongly enco
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int Integer/long long Same as int a
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zend_module_entry rot13_module_entr
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for(i=0, ch=arg; i= 'A')&&(*ch
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if (extension_loaded($module)) { $s
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SWF_DIR=$i AC_MSG_RESULT(found in $
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If you compile the Apache module ve
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For example: zval **old, *new; *new
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The value returned from a PHP funct
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A More Complex Example Here’s an
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Table 14-4. RETURN-related convenie
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* ... */ }; PHP_MINIT_FUNCTION(foo)
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using SEPARATE_ZVAL( ), initializes
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The struct looks like this in the p
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zend_hash_update(&EG(symbol_table),
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Resources A resource is a generic d
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Chapter 15 CHAPTER 15 PHP on Window
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3. Windows 95/98/Me: the Windows sy
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Then explicitly load the module wit
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un under IIS, you will need to reim
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External Commands PHP uses the defa
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This creates a reference (VT_BYREF)
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Figure 15-3. Gleaning syntax from W
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Now we can complete the invoice wit
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multiple Workbooks, each of which c
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Example 15-4. Querying Excel via OD
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• Applications that want to use t
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Example 15-5. Add new phone number,
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Files, directories, and filesystem
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addcslashes string addcslashes(stri
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array_merge array array_merge(array
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array_search mixed array_search(mix
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asort void asort(array array[, int
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call_user_func mixed call_user_func
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chown bool chown(string path, mixed
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cos double cos(double value) Return
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Any characters in the format string
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each array each(array array) Create
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Any number of these options can be
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fflush int fflush(int handle) Commi
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filemtime int filemtime(string path
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If include is specified and is true
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ftell int ftell(int handle) Returns
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get_current_user string get_current
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get_parent_class string get_parent_
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getmypid int getmypid( ) Returns th
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header void header(string header[,
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implode string implode(array string
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is_double bool is_double(mixed valu
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is_scalar bool is_scalar(mixed valu
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Calculates the Levenshtein distance
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log double log(double number) Retur
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mkdir int mkdir(string path, int mo
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number_format string number_format(
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openlog int openlog(string identity
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parse_url array parse_url(string ur
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phpinfo void phpinfo([int what]) Ou
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printf int printf(string format[, m
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eaddir string readdir(int handle) R
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ound double round(double number[, i
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setlocale string setlocale(mixed ca
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sort void sort(array array[, int fl
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str_pad string str_pad(string strin
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%H Hour in 24-hour format, includin
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strncmp int strncmp(string one, str
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strtr string strtr(string string, s
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tmpfile int tmpfile( ) Creates a te
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unregister_tick_function void unreg
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wordwrap string wordwrap(string str
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old versions of aspell, you should
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DBM For very simple database instal
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Hyperwave Hyperwave is a database f
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mcrypt This extension provides an i
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pdflib pdflib provides support for
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Sybase This extension provides supp
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Symbols & (ampersand) &= (bitwise A
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| (vertical bar) |= (bitwise OR ass
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aspell PHP library, 457 assert() fu
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checksums mhash library, 464 valida
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cryptography mcrypt extension, 464
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DTD (Document Type Definition), 263
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System V Semaphores and Shared memo
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calling, 61 for each array element,
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H hash mark (#) in comments, 19 hea
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interlacing GIF images, 246 interna
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masks, using in string searches, 94
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serialization of, 153-157, 438 _ _s
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pdf_open_file() function, 234 pdf_p
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with echo, 76 with print() function
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S Sablotron C library (XSLT support
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sql_regcase() function, 443 sqrt()
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tan() function, 451 target encoding
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function parameters, 33 functions f
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xml_set_unparsed_entity_decl_handle
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