philip Tue Mar 18 04:09:12 2003 EDT
Modified files:
/phpdoc/en/faq using.xml
Log:
A massive update that brings faq into the 4.2.0ish era. Expand examples, implement
magic quotes and register_globals entities, and various rewrites.
Index: phpdoc/en/faq/using.xml
diff -u phpdoc/en/faq/using.xml:1.22 phpdoc/en/faq/using.xml:1.23
--- phpdoc/en/faq/using.xml:1.22 Sun Mar 16 18:24:47 2003
+++ phpdoc/en/faq/using.xml Tue Mar 18 04:09:12 2003
@@ -1,12 +1,12 @@
<?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.22 $ -->
+<!-- $Revision: 1.23 $ -->
<chapter id="faq.using">
<title>Using PHP</title>
<titleabbrev>Using PHP</titleabbrev>
<para>
- This section gathers most common errors you can
- face, while writing PHP scripts.
+ This section gathers many common errors that you may face
+ while writing PHP scripts.
</para>
<qandaset>
@@ -19,44 +19,85 @@
</question>
<answer>
<para>
- Make sure that the <link linkend="ini.track-vars">track_vars</link>
- feature is enabled in your &php.ini;
- file. Since PHP 4.0.3, this feature is always on. When
- <literal>track_vars</literal> is on, it creates some
- associative arrays, the most important here is:
- <literal>$_POST</literal> (this used to be called
- <literal>$HTTP_POST_VARS</literal> in <literal>PHP</literal> versions
- prior 4.1.0). So, to write a generic
- script to handle POST method variables you would
- need something similar to the following:
+ PHP offers many <link linkend="language.variables.predefined">
+ predefined variables</link>, like the superglobal <varname>
+ $_POST</varname>. You may loop through <varname>$_POST</varname>
+ as it's an associate array of all POSTed values. For example, let's
+ simply loop through it with <link linkend="control-structures.foreach">
+ foreach</link>, check for <function>empty</function> values,
+ and print them out.
<programlisting role="php">
<![CDATA[
-foreach ($_POST as $var => $value) {
- echo "$var = $value<br>\n";
+<?php
+$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:\n";
+ var_dump($post);
+} else {
+ print "We have " . count($empty) . " empty values\n";
+ print "Posted:\n"; var_dump($post);
+ print "Empty:\n"; var_dump($empty);
+ exit;
}
+?>
]]>
</programlisting>
</para>
+
+ ¬e.superglobals;
+
</answer>
</qandaentry>
- <qandaentry id="faq.using.singlequotes">
+ <qandaentry id="faq.using.addslashes">
<question>
<para>
I need to convert all single-quotes (') to a backslash
- followed by a single-quote. How can I do this with a
- regular expression?
+ followed by a single-quote (\'). How can I do this with a
+ regular expression? I'd also like to convert " to \" and
+ \ to \\.
</para>
</question>
<answer>
<para>
- First off, take a look at the <function>addslashes</function>
- function. It will do exactly what you want. You should also have
- a look at the <link linkend="ini.magic-quotes-gpc">magic_quotes_gpc</link>
- directive in your &php.ini; file.
+ The function <function>addslashes</function> will do this. See
+ also <function>mysql_escape_string</function>. You may also
+ strip backslashes with <function>stripslashes</function>.
</para>
+
+ ¬e.magicquotes.gpc;
+
</answer>
</qandaentry>
+
+ <qandaentry id="faq.using.stripslashes">
+ <question>
+ <para>
+ 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?
+ </para>
+ </question>
+ <answer>
+ <para>
+ The PHP function <function>stripslashes</function> will strip those
+ backslashes from your <type>string</type>. Most likely the backslashes
+ magically exist because the PHP directive
+ <link linkend="ini.magic-quotes-gpc">magic_quotes_gpc</link> is on.
+ </para>
+
+ ¬e.magicquotes.gpc;
+
+ </answer>
+ </qandaentry>
<qandaentry id="faq.using.wrong-order">
<question>
@@ -129,11 +170,14 @@
</question>
<answer>
<para>
- The functions <function>header</function>,
- <function>setcookie</function> and the session functions need to add
- headers to the output stream. But headers can only be sent before all other
- content, check if your script is sending headers after having already sent
- content.
+ The functions <function>header</function>, <function>setcookie
+ </function>, and the <link linkend="ref.session">session
+ functions</link> 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 <function>
+ headers_sent</function> will check if your script has already sent
+ headers and see also the <link linkend="ref.outcontrol">Output Control
+ functions</link>.
</para>
</answer>
</qandaentry>
@@ -161,6 +205,12 @@
]]>
</programlisting>
</para>
+ <para>
+ See also
+ <function>apache_lookup_uri</function>,
+ <function>apache_response_headers</function>, and
+ <function>fsockopen</function>
+ </para>
</answer>
</qandaentry>
@@ -180,7 +230,9 @@
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:
- <ulink url="&url.iis;">&url.iis;</ulink>.
+ <ulink url="&url.iis;">&url.iis;</ulink> and the manual
+ section on <link linkend="features.http-auth">HTTP Authentication
+ </link>.
</para>
</answer>
</qandaentry>
@@ -218,15 +270,19 @@
<question>
<para>
How am I supposed to mix XML and PHP? It complains
- about my <?xml> tags!
+ about my <?xml tags!
</para>
</question>
<answer>
<para>
- You need to turn off the short tags by setting
- <link linkend="ini.short-open-tag">short_tags</link> to 0 in your
- &php.ini; file, or by using the appropriate Apache directive. You could
- even use a <File> section to do this selectively.
+ In order to embed <?xml straight into your PHP code, you'll have to turn off
+ short tags by having the PHP directive
+ <link linkend="ini.short-open-tag">short_open_tags</link> set to
+ <literal>0</literal>. You cannot set this directive with <function>
+ ini_set</function>. Regardless of <link linkend="ini.short-open-tag">
+ short_open_tags</link> being on or off, you can do something like:
+ <literal><?php echo '<?xml'; ?></literal>. The default
+ for this directive is on.
</para>
</answer>
</qandaentry>
@@ -254,19 +310,24 @@
<qandaentry id="faq.using.variables">
<question>
<para>
- Where can I find a complete list of pre-set variables available
- to me, and why are these not documented in the PHP documentation?
+ Where can I find a complete list of variables are available to me
+ in PHP?
</para>
</question>
<answer>
<para>
- The best way is to stick a <literal><?php phpinfo(); ?></literal>
- part on a page and load it up. This will show you all sorts of
- information about your PHP setup, including a list of both
- environment variables and also special variables set by your
- web server. This list can't really be documented in the PHP
- documentation because it will change from one server to another.
+ Read the manual page on <link linkend="language.variables.predefined">
+ predefined variables</link> 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
+ <function>phpinfo</function> function. Be sure to read the manual
+ section on <link linkend="language.variables.external">variables from
+ outside of PHP</link> as it describes common scenerios for
+ external variables, like from a HTML form, a Cookie, and the URL.
</para>
+
+ ¬e.registerglobals;
+
</answer>
</qandaentry>
@@ -280,19 +341,27 @@
</question>
<answer>
<para>
- Environment variables are normal global variables, so you must
- either declare them as global variables in your function (by using
- "<literal>global $DOCUMENT_ROOT;</literal>", for example) or by using
- the global variable array (ie, "<literal>$GLOBALS["DOCUMENT_ROOT"]</literal>").
- </para>
- <note>
- <para>
- Since PHP 4.1.0 you can also use the superglobal array
- <literal>$_SERVER</literal> which is available in every function.
- For example, you can now use <literal>$_SERVER["DOCUMENT_ROOT"]</literal>
- instead of <literal>$DOCUMENT_ROOT</literal>.
- </para>
- </note>
+ It's important to realize that the PHP directive <link linkend="
+ ini.register-globals">register_globals</link> also affects server
+ and environment variables. When register_globals = off (the default
+ is off since PHP 4.2.0), <varname>$DOCUMENT_ROOT</varname> will
+ not exist. Instead, use <varname>$_SERVER['DOCUMENT_ROOT']
+ </varname>. If register_globals = on then the variables
+ <varname>$DOCUMENT_ROOT</varname> and
+ <varname>$GLOBALS['DOCUMENT_ROOT']</varname> will also exist.
+ </para>
+ <para>
+ If you're sure register_globals = on and wonder why
+ <varname>$DOCUMENT_ROOT</varname> isn't available inside functions,
+ it's because these are like any other variables and would
+ require <literal>global $DOCUMENT_ROOT</literal> inside the
+ function. See also the manual page on
+ <link linkend="language.variables.scope">variable scope</link>. It's
+ preferred to code with register_globals = off.
+ </para>
+
+ ¬e.superglobals;
+
</answer>
</qandaentry>
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