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- <IMG SRC='/gifs/spacer.gif' WIDTH=5 HEIGHT=1 BORDER=0 ALT=' '><FONT FACE="tahoma, verdana, arial, helvetica, sans-serif" SIZE=4><B>Frequently Asked Questions</B></FONT><BR>
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- <!-- start body -->
-
-<P>This is a list of Frequently Asked Questions about PHP3 and
-their answers. If you have suggestions or additions, send them to
-<CODE>php3@lists.php.net</CODE>.
-
-<HR noshade>
-
-<H2>General Information</H2>
-
-<DL>
- <DT><B>
- What is PHP3?
- </B></DT>
- <DD>
- From the <A href="http://www.php.net/manual/">manual</A>:
-
- <BLOCKQUOTE>
- <P>PHP Version 3.0 is an HTML-embedded scripting
- language. Much of its syntax is borrowed from C, Java and Perl with a
- couple of unique PHP-specific features thrown in. The goal of the language
- is to allow web developers to write dynamically generated pages quickly.
- </BLOCKQUOTE>
- <P>
- </DD>
-
- <DT><B>
- What is its relation to PHP/FI?
- </B></DT>
- <DD>
- PHP3 is the successor to PHP/FI 2.0.
- <P>
- </DD>
- <DT><B>
- Can I run both PHP/FI 2.0 and PHP3 at the same time?
- </B></DT>
- <DD>
- Yes, PHP3 was written so as to not interfere with an existing PHP/FI 2 installation.
- Instructions for building Apache 1.3.0 with both PHP/FI 2 and PHP3 modules can be
- found <a href="php2.php3">HERE</a>.
- <P>
-
- <DT><B>
- What are the differences between PHP3 and PHP/FI 2.0?
- </B></DT>
- <DD>
- For a complete list of the changes, read the <A
- href="changes.php3">CHANGES</A> file included in the PHP3
- distribution. Some highlights:
-
- <UL>
- <LI>All-new parser.
- <LI>Persistent database connections.
- <LI>A native Windows95/NT port.
- <LI>IMAP, SNMP, and LDAP extensions.
- </UL>
- <P>
- </DD>
-
- <DT><B>
- I heard it's possible to access Microsoft SQL Server from PHP3. How?
- </B></DT>
- <DD>
- On Windows 95/NT machines, you can simply use the included ODBC support
- and the correct ODBC driver.
-
- <P>On Unix machines, you can use the Sybase-CT driver
- to access Microsoft SQL Servers because they are (at
- least mostly) protocol-compatible. Sybase has made a <A
- href="/extra/ctlib-linux-elf.tar.gz">free version of the necessary
- libraries for Linux systems</A>. For other Unix operating systems,
- you need to contact Sybase for the correct libraries (which cost
- money).
- <P>
- </DD>
-
- <DT><B>
- Can I access Microsoft Access databases?
- </B></DT>
- <DD>
- Yes. You already have all the tools you need if you are running
- entirely under Windows 95 or NT, where you can use ODBC and Microsoft's
- ODBC drivers for Microsoft Access databases. From other platforms, you
- would need to have a server running Windows NT (or possibly Windows 95)
- which you connected to using ODBC drivers from your other platform and
- <A href="http://www.openlinksw.com/">OpenLink Software's ODBC Agent</A>
- software, which runs US$4,000.
-
- <P>Some better alternatives are to use an SQL server that has
- Windows ODBC drivers and use that to store the data, which you can
- then access from Microsoft Access (using ODBC) and PHP3 (using the
- built-in drivers), or to use an intermediary file format that Access
- and PHP3 both understand, such as flat-files or dBase databases.
- <P>
- </DD>
-
- <DT><B>
- Is there a PHP3 mailing list?
- </B></DT>
- <DD>
- Of course! To subscribe, send mail to
- <CODE>php3-subscribe@lists.php.net</CODE>. You don't need to include
- anything special in the subject or body of the message.
-
- <P>To unsubscribe, send mail to <CODE>php3-unsubscribe@lists.php.net</CODE>.
- <P>
- </DD>
-
- <DT><B>
- Help! I can't seem to subscribe to the mailing list!
- </B></DT>
- <DT><B>
- Help! I can't seem to unsubscribe from the mailing list!
- </B></DT>
- <DD>
- If you have problems subscribing to or unsubscribing from the
- PHP3 mailng list, it may be because the mailing list software
- can't figure out the correct mailing address to use. If
- your email address was <CODE>joeblow@example.com</CODE>,
- you can send your subscription request to
- <CODE>php3-subscribe-joeblow=example.com@lists.php.net</CODE>,
- or your unsubscription request to
- <CODE>php3-unsubscribe-joeblow=example.com@lists.php.net</CODE>.
- <P>
- </DD>
-
- <DT><B>
- Is there an archive of the mailing list anywhere?
- </B></DT>
- <DD>
- Yes, it's located at <A
- href="http://www.tryc.on.ca/php3.html">http://www.tryc.on.ca/php3.html</A>.
- </DD>
-</DL>
-
-<HR noshade>
-
-<H2>Obtaining PHP3</H2>
-
-<DL>
- <DT><B>
- Where can I obtain PHP3?
- </B></DT>
- <DD>
- You can download PHP3 from any of the members of the
- PHP3 network of sites. These can be found at <A
- href="http://www.php.net/">http://www.php.net/</A>.
- You can also use anonymous CVS to get the absolute latest
- version of the source. For more information, go to <A
- href="http://ca.php.net/cvsweb.cgi">http://ca.php.net/cvsweb.cgi</A>.
- <P>
- </DD>
-
- <DT><B>
- Are pre-compiled binary versions available?
- </B></DT>
- <DD>
- Yes, as long as you're looking for binaries for Windows 95 or NT.
- They're available in the same place as the source.
- <P>
- </DD>
-
- <DT><B>
- Where can I get libraries needed to compile some of the optional
- PHP3 extensions?
- </B></DT>
- <DD>
- <B>Note:</B> Those marked with * are not thread-safe libraries, and
- should not be used with PHP3 as a server module in the multi-threaded
- Windows web servers (IIS, Netscape). This does not matter in Unix
- environments, yet.
-
- <UL>
- <LI>LDAP* (unix): <A href="ftp://terminator.rs.itd.umich.edu/ldap/ldap-3.3.tar.Z">ftp://terminator.rs.itd.umich.edu/ldap/ldap-3.3.tar.Z</A>
- <LI>LDAP (unix/win): <A HREF="http://developer.netscape.com/tech/directory/downloads.html" TARGET="_top">Netscape Directory (LDAP) SDK 1.1</A>
- There is also a free LDAP server at: <A href="ftp://ftp.critical-angle.com/pub/cai/slapd/">ftp://ftp.critical-angle.com/pub/cai/slapd/</A>.
- <LI>Berkeley DB2 (Unix/Win): <A href="http://www.sleepycat.com/">http://www.sleepycat.com/</A>
- <LI>SNMP* (Unix): <A href="http://www.ece.ucdavis.edu/ucd-snmp/">http://www.ece.ucdavis.edu/ucd-snmp/</A> (Note: PHP3 uses the native SNMP interface in Windows.)
- <LI>GD* (Unix/Win): <A href="http://www.boutell.com/gd/#buildgd">http://www.boutell.com/gd/#buildgd</A>
- <LI>mSQL* (Unix): <A href="http://www.hughes.com.au/">http://www.hughes.com.au/</A>
- <LI>mSQL* (Win) : <A HREF="http://blnet.com/msqlpc/">MSQL PC Home Page</a>
- <LI>MySQL (Unix): <A href="http://www.tcx.se/">http://www.tcx.se/</A>
- <LI>IMAP* (Win/Unix): <A HREF="ftp://ftp.cac.washington.edu/imap/old/imap-4.tar.Z">ftp://ftp.cac.washington.edu/imap/old/imap-4.tar.Z</A>
- <LI>Sybase-CT* (Linux, libc5): <A href="/extra/ctlib-linux-elf.tar.gz">Available locally</A>
- <LI>FreeType: <A HREF="http://www.physiol.med.tu-muenchen.de/~robert/freetype.html">http://www.physiol.med.tu-muenchen.de/~robert/freetype.html</A>
- <LI>ZLib (Unix/Win32): <A HREF="http://www.cdrom.com/pub/infozip/zlib/">http://www.cdrom.com/pub/infozip/zlib/</a>
- </UL>
- <P>
- </DD>
-
- <DT><B>
- How do I get these libraries to work?
- </B></DT>
- <DD>
- You will need to follow instructions provided with the library. Some of
- these libraries are detected automatically when you run the 'configure'
- script of PHP3 (such as the GD library), and others you will have to
- enable using '--with-EXTENSION' options to 'configure'. Run 'configure
- --help' for a listing of these.
- <P>
- </DD>
-
- <DT><B>
- I got the latest version of the PHP3 source code from the CVS
- repository on my Windows 95/NT machine, what do I need to compile it?
- </B></DT>
- <DD>
- First, you will need Microsoft Visual C++ v5 (v4 may do
- it also, but we do it with v5), and you will need to <A
- href="http://www.php.net/win32/makeparser.zip">download Bison and
- Flex</A>. You will need to put Bison and Flex somewhere in your
- path, or add their location to your path. Then run the batch file
- 'makeparser' before compiling with MSVC. You also may need to edit
- some settings in the project settings. You should be familier enough
- with MSVC to know what to do ;).
- <P>
- </DD>
-</DL>
-
- <DT><B>
- Where do I find the Browser Capabilities File?
- </B></DT>
- <DD>
- You can find PHP's own browscap.ini file at <a href="http://php.netvision.net.il/browscap/">http://php.netvision.net.il/browscap/</a>.
- There is also another browscap.ini file at <a href="http://www.cyscape.com/asp/browscap/">http://www.cyscape.com/asp/browscap/</a>.
- <P>
- </DD>
-
-<HR noshade>
-
-<H2>Installation</H2>
-
-<P>To install PHP3, follow the instructions in the <A
-href="http://ca.php.net/cvsweb.cgi/INSTALL?rev=1.18">INSTALL</A>
-file located in the distribution. Windows
-95 and NT users should also read the <A
-href="http://ca.php.net/cvsweb.cgi/README.WIN32?rev=1.3">README.WIN32</A>
-file. There are also some helpful hints for Windows users here:
-<a href="http://leonard.staff.imaginet.fr/Doc/php/configuration_NT.html">
-http://leonard.staff.imaginet.fr/Doc/php/configuration_NT.html</a>.
-
-<H3>Common Problems</H3>
-
-<DL>
- <DT><B>
- I got the latest version of PHP3 using the anonymous CVS service,
- but there's no configure script!
- </B></DT>
- <DD>
- You have to have the GNU autoconf package installed so you can
- generate the configure script from configure.in. Just run
- <CODE>autoconf</CODE> in the top-level directory after getting
- the sources from the CVS server. (Also, unless you run configure
- with the <CODE>--enable-maintainer-mode</CODE> option, the
- configure script will not automatically get rebuilt when the
- configure.in file is updated, so you should make sure to do that
- manually when you notice configure.in has changed. One symptom
- of this is finding things like @VARIABLE@ in your Makefile after
- configure or config.status is run.
- <P>
- </DD>
- <DT><B>
- I'm having problems configuring PHP3 to work with Apache. It says
- it can't find httpd.h, but it's right where I said it is!
- </B></DT>
- <DD>
- You need to tell the configure/setup script the location of the
- <EM>top-level</EM> of your Apache source tree. This means that
- you want to specify '<CODE>--with-apache=/path/to/apache</CODE>'
- and <EM>not</EM> '<CODE>--with-apache=/path/to/apache/src</CODE>'.
- <P>
- </DD>
- <DT><B>
- When I run configure, it says that it can't find the include files or
- library for GD, gdbm, or some other package!
- </B></DT>
- <DD>
- You can make the configure script looks for header files and libraries
- in non-standard locations by specifying additional flags to pass to
- the C preprocessor and linker, such as:
-<FONT FACE="monospaced"><PRE>
- CPPFLAGS=-I/path/to/include LDFLAGS=-L/path/to/library ./configure
-</PRE></FONT>
- If you're using a csh-variant for your login shell (why?), it would be:
-<FONT FACE="monospaced"><PRE>
- env CPPFLAGS=-I/path/to/include LDFLAGS=-L/path/to/library ./configure
-</PRE></FONT>
- <P>
- </DD>
-
- <DT><B>
- When it is compiling the file language-parser.tab.c, it gives me errors
- that say 'yytname undeclared'.
- </B></DT>
- <DD>
- You need to update your version of Bison. You can find the latest version
- at <A href="ftp://prep.ai.mit.edu/pub/gnu/">ftp://prep.ai.mit.edu/pub/gnu/</A>.
- <P>
- </DD>
-
- <DT><B>
- When I run 'make', it seems to run fine but then fails when it
- tries to link the final application complaining that it can't find
- some files.
- </B></DT>
- <DD>
- Some old versions of make that don't correctly put the compiled
- versions of the files in the functions directory into that same
- directory. Try running "<CODE>cp *.o functions</CODE>" and then
- re-running 'make' to see if that helps. If it does, you should really
- upgrade to a recent version of GNU make.
- <P>
- </DD>
-
- <DT><B>
- When linking PHP3, it complains about a number of undefined references.
- </B></DT>
- <DD>
- Take a look at the link line and make sure that all of the appropriate
- libraries are being included at the end. Common ones that you might have
- missed are '-ldl' and any libraries required for any database support
- you included.
- <P>
- If you're linking with Apache 1.2.x, did you remember to add the
- appropriate information to the EXTRA_LIBS line of the Configuration
- file and re-rerun Apache's Configure script? See the <A href="http://ca.php.net/cvsweb.cgi/INSTALL?rev=1.18">INSTALL</A> file that
- comes with the distribution for more information.
- <P>
- Some people have also reported that they had to add '-ldl' immediately
- following 'libphp3.a' when linking with Apache.
- <P>
- </DD>
-
- <DT><B>
- I can't figure out how to build PHP3 with Apache 1.3.
- </B></DT>
- <DD>
- <P>This is actually quite easy. Follow these steps carefully:
- <UL>
- <LI>Grab the latest Apache 1.3 distribution from <A href="http://www.apache.org/dist/">www.apache.org</A>.
- <LI>Ungzip and untar it somewhere, for example /usr/local/src/apache-1.3.
- <LI>Compile PHP3 by first running ./configure --with-apache=/<i><path></i>/apache-1.3 (substitute <i><path></i> for the actual path to your apache-1.3 directory.
- <LI>Type 'make' followed by 'make install' to build PHP3 and copy the
- necessary files to the Apache distribution tree.
- <LI>Change directories into to your /<i><path></i>/apache-1.3/src directory and edit the <i>Configuration</i> file. At the end of the file, add: <tt>AddModule modules/php3/libphp3.a</tt>.
- <LI>Type: './Configure' followed by 'make'.
- <LI>You should now have a PHP3-enabled httpd binary!
- </UL>
- <b>Note:</b> You can also use the new Apache ./configure script. See the instructions in the README.configure file
- which is part of your Apache distribution. Also have a look at the INSTALL file in the PHP distribution.
- <P>
- </DD>
-</DL>
-
-<HR noshade>
-
-<H2>Using PHP3</H2>
-
-<DL>
- <DT><B>
- I would like to write a generic PHP script that can handle data coming
- from any form. How do I know which POST method variables are available?
- </B></DT>
- <DD>
- You need to compile PHP with the "--enable-track-vars" configure switch.
- This creates three associative arrays. $HTTP_GET_VARS, $HTTP_POST_VARS
- and $HTTP_COOKIE_VARS. So, to write a generic script to handle POST
- method variables you would need something similar to the following:<PRE>
- while (list($var, $value) = each($HTTP_POST_VARS)) {
- echo "$var = $value<br>n";
- }</PRE>
- <P>
- </DD>
-
- <DT><B>
- I need to convert all single-quotes (') to a backslash followed by
- a single-quote. How can I do this with a regular expression?
- </B></DT>
- <DD>
- First off, take a look at the <A href="manual/function.addslashes.php3">addslashes()</A> function. It will do
- exactly what you want.
- <P>
- The ereg_replace magic you're looking for, however, is simply:<PRE>
- $escaped = ereg_replace("'", "\'", $input);</PRE>
- <P>
- </DD>
-
- <DT><B>
- When I do the following, the output is printed in the wrong order:<PRE>
- function myfunc($argument) {
- echo $myfunc + 10;
- }
- $variable = 10;
- echo "myfunc($variable) = " . myfunc($variable);
- </PRE>
- <P>What's going on?
- </B></DT>
- <DD>
- To be able to use the results of your function in an expression (such
- as concatenating it with other strings in the example above), you need
- to <B>return</B> the value, not echo it.
- <P>
- </DD>
-
- <DT><B>
- Hey, what happened to my newlines in:
-<PRE>
-<PRE>
- 1 <?echo $result[1];?>
- 2 <?echo $result[2];?>
-</PRE>
- </B></DT>
- <DD>
- In PHP, the ending for a block of code is either "?>" <B>or</B>
- "?>n" (where n means a newline). This means that you need to
- insert an extra newline after each block of PHP code in the above
- example.
- <P>
- Why does PHP do this? Because when formatting normal HTML, this
- usually makes your life easier because you don't want that newline,
- but you'd have to create extremely long lines or otherwise make the
- raw page source unreadable to achieve that effect.
- <P>
- </DD>
-
- <DT><B>
- I need to access information in the request header directly. How can
- I do this?
- </B></DT>
- <DD>
- The getallheaders() function will do this if you are running PHP as a
- module. So, the following bit of code will show you all the request
- headers:<PRE>
- $headers = getallheaders();
- for(reset($headers); $key = key($headers); next($headers)) {
- echo "headers[$key] = ".$headers[$key]."<br>n";
- }
-</PRE>
- <P>
- </DD>
-
- <DT><B>
- When I try to use authentication with IIS I get 'No Input file specified'
- </B></DT>
- <DD>
- The security model of IIS is at fault here. This is a problem
- common to all CGI programs running under IIS. A workaround is
- to create a plain HTML file (not parsed by php) as the entry page
- into an authenticated directory. Then use a META tag to redirect
- to the PHP page, or have a link to the PHP page. PHP will
- then recognize the authentication correctly. When the ISAPI
- module is ready, this will no longer be a problem. This should
- not effect other NT web servers. For more information, see: <A
- href="http://support.microsoft.com/support/kb/articles/q160/4/22.asp"
- target="_new">http://support.microsoft.com/support/kb/articles/q160/4/22.asp</A>.
- <P>
- </DD>
-
- <DT><B>
- I've followed all the instructions, but still can't get PHP and IIS
- to work together!
- </B></DT>
- <DD>
- Make sure any user who needs to run a PHP script has the rights
- to run php.exe! IIS uses an anonymous user which is added at the
- time IIS is installed. This user needs rights to php.exe. Also,
- any authenticated user will also need rights to execute php.exe.
- <P>
- </DD>
-
-</DL>
-
-<H3>New Features</H3>
-
-<DL>
- <DT><B>
- I saw PHP3 offers persistent database connections. What does that mean?
- </B></DT>
- <DD>
- Persistent connections are SQL links that do not close when the
- execution of your script ends. When a persistent connection is
- requested, PHP checks if there's already an identical persistent
- connection (that remained open from earlier) - and if it exists, it
- uses it. If it does not exist, it creates the link. An 'identical'
- connection is a connection that was opened to the same host, with
- the same username and the same password (where applicable).
-
- <P>People who aren't thoroughly familiar with the way web servers
- work and distribute the load may mistake persistent connects for what
- they're not. In particular, they do <B>not</B> give you an ability
- to open 'user sessions' on the same SQL link, they do <B>not</B>
- give you an ability to build up a transaction efficently, and they
- don't do a whole lot of other things. In fact, to be extremely
- clear about the subject, persistent connections don't give you <B>any</B>
- functionality that wasn't possible with their non-persistent brothers.
-
- <P>Why?
-
- <P>This has to do with the way web servers work. There are three ways
- in which your web server can utilize PHP to generate web pages.
-
- <P>The first method is to use PHP as a CGI "wrapper". When run this
- way, an instance of the PHP interpreter is created and destroyed for
- every page request (for a PHP page) to your web server. Because it
- is destroyed after every request, any resources that it acquires (such
- as a link to an SQL database server) are closed when it is destroyed.
- In this case, you do not gain anything from trying to use persistent
- connections -- they simply don't persist.
-
- <P>The second, and most popular, method is to run PHP as a module
- in a <I>multiprocess</I> web server, which currently only includes
- Apache. A multiprocess server typically has one process (the parent)
- which coordinates a set of processes (its children) who actually do
- the work of serving up web pages. When each request comes in from a a
- client, it is handed off to one of the children that is not already
- serving another client. This means that when the same client makes
- a second request to the server, it may be serviced by a different
- child process than the first time. What a persistent connection does
- for you in this case it make it so each child process only needs
- to connect to your SQL server the first time that it serves a page
- that makes us of such a connection. When another page then requires
- a connection to the SQL server, it can reuse the connection that
- child established earlier.
-
- <P>The last method is to use PHP as a plug-in for a <I>multithreaded</I>
- web server. Currently this is only theoretical -- PHP does not
- yet work as a plug-in for any multithreaded web servers. Work is
- progressing on support for ISAPI, WSAPI, and NSAPI (on Windows),
- which will all allow PHP to be used as a plug-in on multithreaded
- servers like Netscape FastTrack, Microsoft's Internet Information
- Server (IIS), and O'Reilly's WebSite Pro. When this happens, the
- behavior will be essentially the same as for the multiprocess model
- described before.
-
- <P>If persistent connections don't have any added functionality,
- what are they good for?
-
- <P>The answer here is extremely simple -- efficiency. Persistent
- connections are good if the overhead to create a link to your SQL
- server is high. Whether or not this overhead is really high depends
- on many factors. Like, what kind of database it is, whether or
- not it sits on the same computer on which your web server sits,
- how loaded the machine the SQL server sits on is and so forth.
- The bottom line is that if that connection overhead is high,
- persistent connections help you considerably. They cause the child
- process to simply connect only once for its entire lifespan, instead
- of every time it processes a page that requires connecting to the
- SQL server. This means that for every child that opened a persistent
- connection will have its own open persistent connection to the server.
- For example, if you had 20 different child processes that ran a script
- that made a persistent connection to your SQL server, you'd have 20
- different connections to the SQL server, one from each child.
-
- <P>An important summary. Persistent connections were designed to
- have one-to-one mapping to regular connections. That means that you
- should <B>always</B> be able to replace persistent connections with
- non-persistent connections, and it won't change the way your script
- behaves. It <B>may</B> (and probably will) change the efficiency
- of the script, but not its behavior!
- <P>
- </DD>
-</DL>
-
-<H3>Common Problems</H3>
-
-<DL>
- <DT><b>
- I installed PHP3, but every time I load a document, I get the
- message 'Document Contains No Data'! What's going on here?
- </b></DT>
- <DD>
- This probably means that PHP3 is having some sort of problem
- and is core-dumping. Look in your server error log to see if
- this is the case, and then try to reproduce the problem with
- a small test case. If you know how to use 'gdb', it is very
- helpful when you can provide a backtrace with your bug report
- to help the developers pinpoint the problem.
- <P>
- If your script uses the regular expression functions (<CODE>ereg()</CODE>
- and friends), you should make sure that you compiled PHP3 and
- Apache with the same regular expression package. (This should
- happen automatically with PHP3 and Apache 1.3.)
- <P>
- </DD>
-
- <DT><B>
- I'm trying to access one of the standard CGI variables (such
- as $DOCUMENT_ROOT or $HTTP_REFERER) in a user-defined function,
- and it can't seem to find it. What's wrong?
- </B></DT>
- <DD>
- Environment variables are now normal global variables, so you must
- either declare them as global variables in your function (by using
- "<CODE>global $DOCUMENT_ROOT;</CODE>", for example) or by using
- the global variable array (ie, "<CODE>$GLOBALS["DOCUMENT_ROOT"]</CODE>".
- <P>
- </DD>
-
- <DT><B>
- I think I found a bug! Who should I tell?
- </B></DT>
- <DD>
- You should go to the PHP Bug Database and make sure the bug
- isn't a known bug. If you don't see it in the database, use
- the reporting form to report the bug. It is important to use
- the bug database instead of just sending an email to one of the
- mailing lists because the bug will have a tracking number assigned
- and it will then be possible for you to go back later and check
- on the status of the bug. The bug database can be found at <A
- href="http://ca.php.net/bugs.php3">http://ca.php.net/bugs.php3</A>.
- <P>
- </DD>
-</DL>
-
-<HR noshade>
-
-<H2>Migrating from PHP/FI 2.0</H2>
-
-<H3>Common Problems</H3>
-
-<DL>
- <DT><B>
- When I add two strings together and then echo it, it echoes zero instead
- of the concatenation of the two strings! What's going on? Wouldn't it
- be great if adding two strings just concatenated them together?
- </B></DT>
- <DD>
- PHP3 does not support the overloading of the addition operator for
- strings because values that arrive via the GET and POST methods and
- from databases are always stored as strings. This means that if the
- plus operator were overloaded to concatenate strings, you could add
- what you thought were two numbers and get the wrong result! (For
- example, "4" + "5" would be equal to "45".) One way around this would
- be to explicitly type-cast one or both of the operands, which is what
- PHP/FI 2 did.
-
- <P>This has been simplified in PHP3 by the addition of a real string
- concatenation operator. If you want to "add" two strings together,
- just write it like: <CODE>"this" . "that"</CODE> which will result in
- the string "thisthat".
-
- <P>The answer to the final part of the question is an emphatic no.
- Operator overloading can be a source of great confusion, especially
- when variables aren't very strongly typed to begin with, as they are
- in PHP3.
- <P>
- </DD>
-
- <DT><B>
- When I use the chmod(), umask(), or mkdir() functions, the permissions
- are wrong!
- </B></DT>
- <DD>
- Unlike PHP/FI 2, PHP3 does not interpret the numeric arguments for
- these functions any differently than for any other function, which
- means you need to pass in an octal value if you are specifying an
- octal number, such as:
-<PRE>
- chmod($myfile, 0600);
-</PRE>
- <B>not</B>
-<PRE>
- chmod($myfile, 600);
-</PRE>
- <P>
- </DD>
-
- <DT><B>
- I converted my script from PHP/FI 2.0 to PHP3 syntax, but now it just
- hangs! When I looked at the processes running on my server, there was
- one process that was chewing up all of the CPU cycles!
- </B></DT>
- <DD>
- You probably missed the semi-colon on a <CODE>while
- (condition);</CODE> statement. This will cause PHP3 to spin out of
- control because it is simply executing an empty body for your while
- loop! Change the semi-colon to a colon and it should work correctly.
- <P>
- </DD>
-
- <DT><B>
- My user-functions don't work any more! I get a "Parse error (expecting '('"
- on the first line of the function.
- </B></DT>
- <DD>
- PHP3's function declaration now resembles C function declarations, so
- your function should look like:
- <PRE>
- function printsum($a, $b) {
- echo $a + $b;
- }
- </PRE>
- <P>You can also use old-style function declarations by use the
- 'old_function' designation, like so:
- <PRE>
- old_function printsum $a, $b (
- echo $a + $b;
- );
- </PRE>
- <P>
- </DD>
-</DL>
-
-<HR noshade>
-
-<H2>Credits</H2>
-
-<P>This FAQ was originally written by Jim Winstead. It is currently
-maintained by the PHP Development Team.
-
-<P>
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