PHP India, group, developers, Programmers, Freelancers, Outsourcing FAQ (Frequently Asked Questions)
Category: Main -> Problems While working with PHP
| Question | · 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?
· I need to convert all single-quotes (') to a backslash followed by a single-quote ('). How can I do this with a regular expression? I'd also like to convert " to \" and to \\.
· All my " turn into \" and my ' turn into ', how do I get rid of all these unwanted backslashes? How and why did they get there?
· When I do the following, the output is printed in
the wrong order:
<?php
function myfunc($argument)
{
echo $argument + 10;
}
$variable = 10;
echo "myfunc($variable) = " . myfunc($variable);
?> |
what's going on?
· Hey, what happened to my newlines?
| Answer | | · 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.
<?php
$empty = $post = array();
foreach ($_POST as $varname => $varvalue) {
if (empty($varvalue)) {
$empty[$varname] = $varvalue;
} else {
$post[$varname] = $varvalue;
}
}
print "<pre>";
if (empty($empty)) {
print "None of the POSTed values are empty, posted:
";
var_dump($post);
} else {
print "We have " . count($empty) . " empty values
";
print "Posted:
"; var_dump($post);
print "Empty:
"; var_dump($empty);
exit;
}
?> |
Superglobals: availability note: Since PHP 4.1.0, superglobal arrays such as $_GET
, $_POST, and $_SERVER,
etc. have been available. For more information, read the manual section
on superglobals
[ Back to Top ] | | · I need to convert all single-quotes (') to a backslash followed by a single-quote ('). How can I do this with a regular expression? I'd also like to convert " to \" and to \\. The function addslashes() will do this. See also mysql_escape_string(). You may also strip backslashes with stripslashes().
directive note: magic_quotes_gpc: The PHP directive magic_quotes_gpc defaults to on. It essentially runs addslashes() on all your GET, POST, and COOKIE data. You may use stripslashes() to strip them.
[ Back to Top ]
| | · All my " turn into \" and my ' turn into ', how do I get rid of all these unwanted backslashes? How and why did they get there? The PHP function stripslashes() will strip those backslashes from your string. Most likely the backslashes magically exist because the PHP directive magic_quotes_gpc is on.
directive note: magic_quotes_gpc:
The PHP directive magic_quotes_gpc defaults to on. It essentially runs addslashes() on all your GET, POST, and COOKIE data. You may use stripslashes() to strip them.
[ Back to Top ]
| · When I do the following, the output is printed in
the wrong order:
<?php
function myfunc($argument)
{
echo $argument + 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. [ Back to Top ]
| · 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
"?>
" (where
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.
[ Back to Top ]
| | · 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 functions. [ Back to Top ]
| | · 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:
<?php
$headers = getallheaders();
foreach ($headers as $name => $content) {
echo "headers[$name] = $content<br>
";
}
?>
See also apache_lookup_uri(), apache_response_headers(), and fsockopen()[ Back to Top ]
| | · 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/support/kb/articles/q160/4/22.asp [ Back to Top ]
| | · 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
validator.w3.org, might
be helpful. For example, a missing |
might cause this.
Also, both IE and Lynx ignore any NULs () in
the HTML stream, Netscape does not. The best way to check for this is
to compile the command lineversion 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 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.
Also, both IE and Lynx ignore any NULs () 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 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.[ Back to Top ]
| | · 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/support/kb/articles/q160/4/22.asp and the manual
section on HTTP Authentication
.
[ Back to Top ]
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