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?
PHP offers many
predefined variables, like the superglobal
$_POST. You may loop through $_POST
as it's an associate array of all POSTed values. For example, let's
simply loop through it with
foreach, check for empty() values,
and print them out.
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()
Hey, what happened to my newlines?
<pre> <?php echo "This should be the first line."; ?> <?php echo "This should show up after the new line above."; ?> </pre>
In PHP, the ending for a block of code is either "?>" or
"?>\n" (where \n means a newline). So in the example above,
the echoed sentences will be on one line, because PHP omits
the newlines after the block ending. This means that you need to
insert an extra newline after each block of PHP code to make
it print out one newline.
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.
I get the message 'Warning: Cannot send session cookie - headers already
sent...' or 'Cannot add header information - headers already sent...'.
The functions header(), setcookie(),
and the session
functions need to add headers to the output stream but headers
can only be sent before all other content. There can be no output
before using these functions, output such as HTML. The function
headers_sent() will check if your script has already sent
headers and see also the Output Control
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 an Apache module. So, the following bit
of code will show you all the request headers:
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. With the ISAPI
module, this is not a problem. This should not effect other
NT web servers. For more information, see:
http://support.microsoft.com/kb/q160422/ and the manual
section on HTTP Authentication
Windows: I can't access files shared on another computer using IIS
You have to change the Go to Internet Information
Services. Locate your PHP file and go to its properties.
Go to the File Security tab, Edit -<
Anonymous access and authentication control.
You can fix the problem either by unticking Anonymous
Access and leaving Integrated Window
Authentication ticked, or, by ticking Anonymous
Access and editing the user as he may not have the access
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.
Netscape is more strict regarding HTML tags (such as tables) then
IE. Running your HTML output through a HTML validator, such as
be helpful. For example, a missing </table> might cause this.
Also, 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. In *nix, 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.
How am I supposed to mix XML and PHP? It complains
about my <?xml tags!
In order to embed <?xml straight into your PHP code, you'll have to turn off
short tags by having the PHP directive
short_open_tags set to
0. You cannot set this directive with
ini_set(). Regardless of
short_open_tags being on or off, you can do something like:
<?php echo '<?xml'; ?>. The default
for this directive is on.
How can I use PHP with FrontPage 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 %> code
delimiters. Some of the popular HTML editors handle those more
intelligently (for now). To enable the ASP-style tags, you need
to set the asp_tagsphp.ini variable, or use the
appropriate Apache directive.
Where can I find a complete list of variables are available to me
Read the manual page on
predefined variables as it includes a partial list of predefined
variables available to your script. A complete list of available
variables (and much more information) can be seen by calling the
phpinfo() function. Be sure to read the manual
section on variables from
outside of PHP as it describes common scenarios for
external variables, like from a HTML form, a Cookie, and the URL.
note: Since PHP 4.2.0, the default value for the PHP directive
off, and it is completely removed as of PHP 6.0.0. The PHP community
encourages all to not rely on this directive but instead use other means,
such as the superglobals.
How can I generate PDF files without using the non-free and
commercial libraries ClibPDF and
PDFLib? I'd like something that's
free and doesn't require external PDF libraries.
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?
It's important to realize that the PHP directive register_globals also affects
server and environment variables. When register_globals = off (the
default is off since PHP 4.2.0), $DOCUMENT_ROOT
will not exist. Instead, use $_SERVER['DOCUMENT_ROOT']
. If register_globals = on then the variables
$GLOBALS['DOCUMENT_ROOT'] will also exist.
If you're sure register_globals = on and wonder why
$DOCUMENT_ROOT isn't available inside functions,
it's because these are like any other variables and would
require global $DOCUMENT_ROOT inside the
function. See also the manual page on
variable scope. It's
preferred to code with register_globals = off.
Superglobals: availability note: Since PHP 4.1.0, superglobal arrays such as $_GET
, $_POST, and $_SERVER,
etc. have been available. For more information, read the manual section
A few PHP directives may also take on shorthand byte values, as opposed
to only integer byte values. What are all the available
shorthand byte options? And can I use these outside of php.ini?
The available options are K (for Kilobytes), M (for Megabytes) and G (for
Gigabytes; available since PHP 5.1.0), these are case insensitive.
Anything else assumes bytes.
1M equals one Megabyte or 1048576
bytes. 1K equals one Kilobyte or
1024 bytes. You may not use these shorthand
notations outside of php.ini, instead use an integer
value of bytes. See the ini_get() documentation for
an example on how to convert these values.