PHP3 Frequently Asked Questions

This is a list of Frequently Asked Questions about PHP3 and their answers. If you have suggestions or additions, send them to php3@lists.php.net.

1. General Information
2. Obtaining PHP3
3. Installation
4. Common Problems
5. Using PHP3
6. New Features
7. Common Problems
8. Migrating from PHP2 to PHP3

1. General Information
1.1 What is PHP3?
From the manual:

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.

1.2 What is its relation to PHP/FI?
PHP3 is the successor to PHP/FI 2.0.

1.3 Can I run both PHP/FI 2.0 and PHP3 at the same time?
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 HERE. A different spin on this is HERE, although the first step where the PHP2 regex code is substituted with the PHP3 regex code seems redundant. The two regex dirs are pretty much identical.

1.4 What are the differences between PHP3 and PHP/FI 2.0?
For a complete list of the changes, read the CHANGES file included in the PHP3 distribution. Some highlights:

1.5 I heard it's possible to access Microsoft SQL Server from PHP3. How?
On Windows 95/NT machines, you can simply use the included ODBC support and the correct ODBC driver.

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 free version of the necessary libraries for Linux systems. For other Unix operating systems, you need to contact Sybase for the correct libraries. Also see the answer to the next question - 1.6.

1.6 Can I access Microsoft Access databases?
Yes. You already have all the tools you need if you are running entirely under Windows 95/98 or NT, where you can use ODBC and Microsoft's ODBC drivers for Microsoft Access databases.

If you are running PHP on a Unix box and want to talk to MS-Access on a Windows box you will need Unix ODBC drivers. OpenLink Software has Unix-based ODBC drivers that can do this. There is a free pilot program where you can download an evaluation copy that doesn't expire and prices start at $675 for the commercial supported version.

Another alternative is 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. On this point Tim Hayes from OpenLink software writes:

Using another database as an intermediary is not a good idea, when you can use ODBC from PHP3 straight to your database - i.e. with OpenLink's drivers. If you do need to use an intermediary file format, OpenLink have now released Virtuoso (a virtual database engine) for NT, Linux and other unix platforms. Please visit our website for a free download.

One option that has proven successful is to use MySQL and its MyODBC drivers on Windows and synchronizing the databases. Steve Lawrence writes:

  1. Install MySQL on your platform according to instructions with MySQL. Latest available from www.mysql.org (get it from your mirror!). No special configuration required except when you set up a database, and configure the user account, you should put % in the host field, or the host name of the windows computer you wish to access MySQL with. Make a note of your server name, username, and password.

  2. Download the MyODBC for windows driver from the MySQL site. Latest release is myodbc-2_50_19-win95.zip (NT available too, as well as source code). Install it on your windows machine. You can test the operation with the utilities included with this program.

  3. Create a user or system dsn in your ODBC administrator, located in the control panel. Make up a dsn name, enter your hostname, user name, password, port, etc for you MySQL database configured in step 1.

  4. Install Access with a full install, this makes sure you get the proper add-ins.. at the least you will need ODBC support and the linked table manager.

  5. Now the fun part! Create a new access database. In the table window right click and select Link Tables, or under the file menu option, select Get External Data and then Link Tables. When the file browser box comes up, select files of type: ODBC. Select System dsn and the name of your dsn created in step 3. Select the table to link, press ok, and presto! you can now open the table and add/delete/edit data on your MySQL server! You can also build queries, import/export tables to MySQL, build forms and reports, etc.

Tips and Tricks: - You can construct your tables in access and export them to MySQL, then link them back in. That makes table creation quick.
- When creating tables in access, you must have a primary key defined in order to have write access to the table in access. Make sure you create a primary key in MySQL before linking in access.
- If you change a table in MySQL, you have to re-link it in access. Go to tools>add-ins>linked table manager, cruise to your ODBC DSN, and select the table to re-link from there. you can also move your dsn source around there, just hit the always prompt for new location checkbox before pressing ok.

1.7 Is there a PHP3 mailing list?
Of course! To subscribe, send mail to php3-subscribe@lists.php.net. You don't need to include anything special in the subject or body of the message.

To unsubscribe, send mail to php3-unsubscribe@lists.php.net.

1.8 Help! I can't seem to subscribe to the mailing list!
Help! I can't seem to unsubscribe from the mailing list!
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 joeblow@example.com, you can send your subscription request to php3-subscribe-joeblow=example.com@lists.php.net, or your unsubscription request to php3-unsubscribe-joeblow=example.com@lists.php.net.

1.9 Is there an archive of the mailing list anywhere?
Yes, you will find a list of archive sites on the Support page.

1.10 How did you do those pop-out windows for the Search and Mirror buttons?
Our site designer, Colin Viebrock (cmv@privateworld.com), says:

Those fancy pop-out layers are done with Dynamic HTML (DHTML), Cascading Style Sheets (CSS) and Javascript (version 1.2).

There are plenty of references on the web about DHTML and CSS, including:

But your best source of information is to view the source code to the pages on the PHP site. To see the actual DHTML/Javascript code, use your browser's "View Source" function. To see how this code was generated dynamically using PHP3, click on the "Source" button in the upper-right corner of any PHP page. You will probably also want to view the source of the "shared.inc" file - there is a link to it at the bottom of every source page.

1.11 Can I access Empress RDBMS databases?
Yes. PHP 3.0.6 and Empress RDBMS v8.10 and higher are compatible.

You already have all the tools you need if you are running entirely under Windows 95/98 or NT, where you can use ODBC and the Empress ODBC driver for Windows.

If you are running PHP on a Unix box and want to access Empress databases, you can link the Empress ODBC client driver directly into the PHP unified ODBC API.
Note that does NOT make PHP an ODBC client. The unified ODBC interface simplies uses the ODBC application program interface (API).

Because Empress uses the PHP unified ODBC interface it has very little explicit Empress specific syntax. It is of course possible to use Empress specific SQL in the SQL statements themselves, but this does not affect the interface. It is a good general policy to stick to ANSI standard SQL whenever possible.

Empress Specifics: The only item which is specific to Empress in PHP is that there are two methods for specifying the DNS in the odbc_connect () and odbc_pconnect () functions. The connect syntax is:
odbc_connect (dsn, user_id, password)
odbc_pconnect (dsn, user_id, password)
For Empress dsn can be specified as either:
Data source name
This is the logical database name specified in the ODBC.INI file.
A full connection string, as specified in the ODBC standard.
eg
dsn="DATABASE=db_name;SERVER=server_name;PORT=server_port"

Note that there are other options for this string. But the three shown above are the most important for use with PHP.

Which of these you use is up to you. There are advantages and disadvantages to both. Using the full connection string means that you do NOT require an ODBC.INI file to access the database. However, if you move the datasource, or change the port on which the RDBMS server listens, you will have to modify every call to the odbc_connect/pconnect function.
The choice is yours...

Empress Installation: In order to add the Empress interface to PHP you require an Empress RDBMS with the Empress Connectivity option. If your PHP installation is on the same platform as the RDBMS then setting EMPRESS_PATH to the installation directory will automatically locate the Empress ODBC client driver. However, if the PHP installation is on a separate platform from the RDBMS you will also require an ODBC client on that platform, and you will need to specify the location of the driver when configuring the PHP installation.

2. Obtaining PHP3
2.1 Where can I obtain PHP3?
You can download PHP3 from any of the members of the PHP3 network of sites. These can be found at http://www.php.net/. You can also use anonymous CVS to get the absolute latest version of the source. For more information, go to http://cvs.php.net.

2.2 Are pre-compiled binary versions available?
Yes, although they are not always up to date. The Windows binary is generally current, but the Unix binaries lag behind and are only available for certain platforms. All download are available in the Downloads section.

2.3 Where can I get libraries needed to compile some of the optional PHP3 extensions?
Note: 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.

2.4 How do I get these libraries to work?
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.

2.5 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?
First, you will need Microsoft Visual C++ v5 (v4 may do it also, but we do it with v5), and you will need to download Bison and Flex. 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 ;).

2.6 Where do I find the Browser Capabilities File?
You can find PHP's own browscap.ini file at http://php.netvision.net.il/browscap/. There is also another browscap.ini file at http://www.cyscape.com/asp/browscap/.

3. Installation

To install PHP3, follow the instructions in the INSTALL file located in the distribution. Windows 95 and NT users should also read the README.WIN32 file. There are also some helpful hints for Windows users here: http://leo.karefil.com/Doc/php/configuration_NT.html.

If you are trying to install PHP for use with Netscape's web server on Unix see: http://www.webgenx.com/Kwazy/phpunix.html

3.1 Where should my php3.ini file be located?
By default on UNIX it should be in /usr/local/lib. Most people will want to change this at compile-time with the --with-config-file-path flag. You would, for example, set it to something like: 
	--with-config-file-path=/etc
And then you would copy php3.ini-dist from the distribution to /etc/php3.ini and edit it to make any local changes you want.

3.2 I installed PHP3 using RPMS, but Apache isn't processing the php3 pages! What's going on here?

3.3 I installed PHP3 using RPMS, but it doesn't compile with the database support I need! What's going on here?
Due to the way PHP is currently built, it is not easy to build a complete flexible PHP RPM. This issue will be addressed in PHP4. For PHP3, we currently suggest you use the mechanism described in the INSTALL.REDHAT file in the PHP distribution. If you insist on using an RPM version of PHP, read on...
Currently the RPM packagers are setting up the RPMS to install without database support to simplify installations AND because RPMS use /usr/ instead of the standard /usr/local/ directory for files. You need to tell the RPM spec file which databases to support and the location of the top-level of your database server.
This example will explain the process of adding support for the popular MySQL database server, using the mod installation for Apache.
Of course all of this information can be adjusted for any database server that PHP3 supports. I will assume you installed MySQL and Apache completely with RPMS for this example as well. Make sure you restart Apache, and you now have PHP with MySQL support using RPM's.

4. Common Problems
4.1 I got the latest version of PHP3 using the anonymous CVS service, but there's no configure script!
You have to have the GNU autoconf package installed so you can generate the configure script from configure.in. Just run autoconf in the top-level directory after getting the sources from the CVS server. (Also, unless you run configure with the --enable-maintainer-mode 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.

4.2 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!
You need to tell the configure/setup script the location of the top-level of your Apache source tree. This means that you want to specify '--with-apache=/path/to/apache' and not '--with-apache=/path/to/apache/src'.

4.3 When I run configure, it says that it can't find the include files or library for GD, gdbm, or some other package!
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: 
    CPPFLAGS=-I/path/to/include LDFLAGS=-L/path/to/library ./configure
If you're using a csh-variant for your login shell (why?), it would be: 
    env CPPFLAGS=-I/path/to/include LDFLAGS=-L/path/to/library ./configure

4.4 When it is compiling the file language-parser.tab.c, it gives me errors that say 'yytname undeclared'.
You need to update your version of Bison. You can find the latest version at ftp://prep.ai.mit.edu/pub/gnu/.

4.5 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.
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 "cp *.o functions" and then re-running 'make' to see if that helps. If it does, you should really upgrade to a recent version of GNU make.

4.6 When linking PHP3, it complains about a number of undefined references.
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.

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 INSTALL file that comes with the distribution for more information.

Some people have also reported that they had to add '-ldl' immediately following 'libphp3.a' when linking with Apache.

4.7 I can't figure out how to build PHP3 with Apache 1.3.

This is actually quite easy. Follow these steps carefully:

Note: 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.

4.8 I have followed all the steps to install the Apache module version on UNIX, and my PHP scripts show up in my browser or I am being asked to save the file. Help!

This means that the PHP module is not getting invoked for some reason. Three things to check before asking for further help:

4.9 It says to use: --activate-module=src/modules/php3/libphp3.a, but that file doesn't exist, so I changed it to --activate-module=src/modules/php3/libmodphp3.a and it doesn't work!? What's going on?
Well, you decided to try to outsmart the people who wrote those nice step-by-step instructions for you and you have now discovered that these people cannot be outsmarted. The libphp3.a file is not supposed to exist. The Apache build process will create it.

5. Using PHP3
5.1 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?
Make sure that the track_vars feature is enabled in your php3.ini file. If you compiled PHP with "--enable-track-vars" it will be on by default. Alternatively you can enable it at run-time on a per-script basis by putting <?php_track_vars?> at the top of your file. When track_vars is on, it creates three associative arrays. $HTTP_GET_VARS, $HTTP_POST_VARS and $HTTP_COOKIE_VARS. So, to write a generic script to handle POST method variables you would need something similar to the following:
    while (list($var, $value) = each($HTTP_POST_VARS)) {
        echo "$var = $value<br>\n";
    }

5.2 I need to convert all single-quotes (') to a backslash followed by a single-quote. How can I do this with a regular expression?
First off, take a look at the addslashes() function. It will do exactly what you want. You should also have a look at the magic_quotes_gpc directive in your php3.ini file.

The ereg_replace magic you're looking for, however, is simply:

    $escaped = ereg_replace("'", "\\'", $input);

5.3 When I do the following, the output is printed in the wrong order:
      function myfunc($argument) {
        echo $myfunc + 10;
      }
      $variable = 10;
      echo "myfunc($variable) = " . myfunc($variable);

What's going on?

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 return the value, not echo it.

5.4 Hey, what happened to my newlines in: 
<PRE>
  1 <?echo $result[1];?>
  2 <?echo $result[2];?>
In PHP, the ending for a block of code is either "?>" or "?>\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.

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.

5.5 I need to access information in the request header directly. How can I do this?
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:
    $headers = getallheaders();
	for(reset($headers); $key = key($headers); next($headers)) {
        echo "headers[$key] = ".$headers[$key]."<br>\n";
    }

5.6 When I try to use authentication with IIS I get 'No Input file specified'
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: http://support.microsoft.com/support/kb/articles/q160/4/22.asp.

5.7 I've followed all the instructions, but still can't get PHP and IIS to work together!
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. And for IIS4 you need to tell it that PHP is a script engine.

5.8 My PHP script works on IE and Lynx, but on Netscape some of my output is missing. When I do a "View Source" I see the content in IE but not in Netscape. Even when I telnet to port 80 directly the correct content shows up. How can this be? PHP is server-side and my browser can't possibly know that the content it is seeing is generated by PHP, so what is going on?
Very good question! ;) This is a tricky little issue and it has come up twice in the past month as of this writing. Both times I ended up spending a good 20 minutes trying to figure out what the heck was going on. The answer is that both IE and Lynx ignore any NULs (\0) in the HTML stream. Netscape does not. The best way to check for this is to compile the command-line version of PHP (also known as the CGI version) and run your script from the command line and pipe it through 'od -c' and look for any \0 characters. (If you are on Windows you need to find an editor or some other program that lets you look at binary files) When Netscape sees a NUL in a file it will typically not output anything else on that line whereas both IE and Lynx will. If this issue has bitten you, congratulations! You are not alone.

5.9 How do I get all the results from a SELECT MULTIPLE HTML tag?
The SELECT MULTIPLE tag in an HTML construct allows users to select multiple items from a list. These items are then passed to the action handler for the form. The problem is that they are all passed with the same widget name. ie. 
   <SELECT NAME="var" MULTIPLE>
Each selected option will arrive at the action handler as: 
   var=option1
   var=option2
   var=option3
Each option will overwrite the contents of the previous $var variable. The solution is to use PHP's non-indexed array feature. The following should be used: 
   <SELECT NAME="var[]" MULTIPLE>
This tells PHP to treat var as an array and each assignment of a value to var[] adds an item to the array. The first item becomes $var[0], the next $var[1], etc. The count() function can be used to determine how many options were selected, and the sort() function can be used to sort the option array if necessary.

Note that if you are using JavaScript the [] on the element name might cause you problems when you try to refer to the element by name. Use it's numerical form element id instead.

5.10 How am I supposed to mix XML and PHP? It complains about my <?xml> tags!
You need to turn off the short tags by setting short_tags to 0 in your php3.ini file, or by using the php3_short_tags Apache directive. (You could even use a <File> section to do this selectively.) You can also disable and re-enable the short tags in your script using the short_tags() function.

5.11 How can I use PHP with FrontPage or Dreamweaver or some other HTML editor that insists on moving my code around?
One of the easiest things to do is to enable using ASP tags in your PHP code. This allows you to use the ASP-style <% and