Programming PHP

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Figure 13-2. Squid caching The relevant part of the Squid configuration file to set up Squid in this manner is: httpd_accel_host 127.0.0.1 httpd_accel_port 80 httpd_accel_single_host on httpd_accel_uses_host_header on Load balancing and redirection One way to boost performance is to spread the load over a number of machines. A load-balancing system does this by either evenly distributing the load or sending incoming requests to the least loaded machine. A redirector is a program that rewrites incoming URLs, allowing fine-grained control over the distribution of requests to individual server machines. Again, there are hardware HTTP redirectors and load-balancers, but redirection and load balancing can also be done effectively in software. By adding redirection logic to Squid through something like SquidGuard (http://www.squidguard.org), you can do a number of things to improve performance. Figure 13-3 shows how a redirector can load-balance requests either over multiple backend web servers or across separate Apache instances running on different ports on the same server. 127.0.0.1:80 Apache External IP port 80 Squid 127.0.0.1:80 Apache Figure 13-3. Load balancing with SquidGuard 314 | Chapter 13: Application Techniques External IP port 80 Squid 127.0.0.1:80 Apache 192.168.0.1:80 Apache SquidGuard Redirector This is the Title of the Book, eMatter Edition Copyright © 2002 O’Reilly & Associates, Inc. All rights reserved.
MySQL replication Sometimes the database server is the bottleneck—many simultaneous queries can bog down a database server, resulting in sluggish performance. Replication is the solution. Take everything that happens to one database and quickly bring one or more other databases in sync, so you end up with multiple identical databases. This lets you spread your queries across many database servers instead of loading down only one. The most effective model is to use one-way replication, where you have a single master database that gets replicated to a number of slave databases. All database writes go to the master server, and database reads are load-balanced across multiple slave databases. This technique is aimed at architectures that do a lot more reads than writes. Most web applications fit this scenario nicely. Figure 13-4 shows the relationship between the master and slave databases during replication. Figure 13-4. Database replication Many databases support replication, including MySQL, PostgreSQL, and Oracle. Putting it all together For a really high-powered architecture, pull all these concepts together into something like the configuration shown in Figure 13-5. Figure 13-5. Putting it all together Master Slave Slave Slave Apache 1 MySQL slave Squid cache redirector Apache 2 MySQL slave Master MySQL server Apache 3 MySQL slave Using five separate machines—one for the reverse proxy and redirector, three web servers, and one master database server—this architecture can handle a huge number This is the Title of the Book, eMatter Edition Copyright © 2002 O’Reilly & Associates, Inc. All rights reserved. Performance Tuning | 315
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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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The biggest difference between GET
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Figure 7-1. The chunkify form and i
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Example 7-4. Temperature conversion
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Example 7-6. Multiple selection val
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Example 7-8. Sticky multivalued che
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Files are stored in the server’s
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“me@aol” by requiring an at sig
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To mark a document as already expir
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A third technique for maintaining s
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Example 7-10. Preference selection
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Session basics To enable sessions f
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Custom storage By default, PHP stor
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When a session is completed, the de
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Chapter 8 CHAPTER 8 Databases PHP h
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columns, each of which has a name a
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Figure 8-1. The movie page the data
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$db = DB::connect($datasource); if
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string(4) "1962" ["name"]=> string(
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The executeMultiple( ) method takes
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echo "$k"; if (is_array($v)) { a_to
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Two HTML forms are needed to popula
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Example 8-3. Database connection ab
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Example 8-4. Backend administration
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Example 8-5. Adding a business (con
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Example 8-5. Adding a business (con
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The business listings page is illus
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The series of requests sent by the
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many colors as you need. The latter
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image-generating function. Example
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Example 9-4. Adding text to an imag
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Example 9-6. Displaying vertical Tr
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Example 9-8. Caching dynamic button
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You can also take this a step furth
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For a signed integer, the leftmost
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True Color Color Indexes The color
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Chapter 10 CHAPTER 10 PDF Adobe’s
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Figure 10-1. Hello world in a PDF d
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Type, Content-Disposition, and Cont
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Example 10-3. Changing the origin (
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Example 10-4. Text alignment within
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Example 10-5. Changing text attribu
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usr/share/fonts FontAFM LuciduxSans
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Adding an image to a PDF document i
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Example 10-8. Nonproportional scali
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Figure 10-9. A sample path The pdf_
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The width and height parameters spe
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Example 10-11. Using a template Th
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Example 10-12. Using bookmarks and
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Example 10-13. Specifying a link (c
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Figure 10-16. Closed note The conte
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Page 265 and 266: Example 11-1. Generating an XML doc
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Page 275 and 276: Figure 11-2. Book details comment).
Page 277 and 278: Example 11-10. bookparse.xml (conti
Page 279 and 280: Example 11-12. News XSL transform
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Page 285 and 286: Chapter 12 CHAPTER 12 Security PHP
Page 287 and 288: These directives ensure that PHP er
Page 289 and 290: Restrict Filesystem Access to a Spe
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Page 293 and 294: • Any system call (through functi
Page 295 and 296: You can globally disable particular
Page 297 and 298: Chapter 13 CHAPTER 13 Application T
Page 299 and 300: user.template. It uses the {DESTINA
Page 301 and 302: {ARTICLE} might be useful, as it wo
Page 303 and 304: } ob_start('rewrite'); ?> Visit our
Page 305 and 306: To turn off error reporting entirel
Page 307 and 308: Example 13-5. Log-rolling error han
Page 309 and 310: Before you begin optimization, ask
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Page 317 and 318: Chapter 14 CHAPTER 14 Extending PHP
Page 319 and 320: examples, and you are strongly enco
Page 321 and 322: int Integer/long long Same as int a
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Page 325 and 326: for(i=0, ch=arg; i= 'A')&&(*ch
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Page 329 and 330: SWF_DIR=$i AC_MSG_RESULT(found in $
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Page 333 and 334: For example: zval **old, *new; *new
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Page 339 and 340: Table 14-4. RETURN-related convenie
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Page 343 and 344: using SEPARATE_ZVAL( ), initializes
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Page 349 and 350: Resources A resource is a generic d
Page 351 and 352: Chapter 15 CHAPTER 15 PHP on Window
Page 353 and 354: 3. Windows 95/98/Me: the Windows sy
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Page 359 and 360: External Commands PHP uses the defa
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Page 363 and 364: 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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