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><DIV
CLASS="chapter"
><H1
><A
NAME="faq.html"
>Chapter 51. PHP and HTML</A
></H1
><P
> PHP and HTML interact a lot: PHP can generate HTML, and HTML
can pass information to PHP. Before reading these faqs, it's
important you learn how to <A
HREF="language.variables.external.html"
> retrieve variables from outside of PHP</A
>. The manual page on
this topic includes many examples as well. Pay close attention to
what <TT
CLASS="literal"
>register_globals</TT
> means to you too.
</P
><DIV
CLASS="qandaset"
><DL
><DT
>1. <A
HREF="faq.html.html#faq.html.encoding"
> What encoding/decoding do I need when I pass a value through a form/URL?
</A
></DT
><DT
>2. <A
HREF="faq.html.html#faq.html.form-image"
> I'm trying to use an <input type="image"> tag, but
the <TT
CLASS="varname"
>$foo.x</TT
> and <TT
CLASS="varname"
>$foo.y</TT
> variables
aren't available. <TT
CLASS="varname"
>$_GET['foo.x']</TT
> isn't existing
either. Where are they?
</A
></DT
><DT
>3. <A
HREF="faq.html.html#faq.html.arrays"
>How do I create arrays in a HTML <form>?</A
></DT
><DT
>4. <A
HREF="faq.html.html#faq.html.select-multiple"
> How do I get all the results from a select multiple HTML tag?
</A
></DT
></DL
><DIV
CLASS="qandaentry"
><B
><DIV
CLASS="question"
><P
><A
NAME="faq.html.encoding"
></A
><B
>1. </B
>
What encoding/decoding do I need when I pass a value through a form/URL?
</P
></DIV
></B
><DIV
CLASS="answer"
><P
><B
> </B
>
There are several stages for which encoding is important. Assuming that
you have a <A
HREF="language.types.string.html"
><B
CLASS="type"
>string</B
></A
> <TT
CLASS="varname"
>$data</TT
>, which contains
the string you want to pass on in a non-encoded way, these are the
relevant stages:
<P
></P
><UL
><LI
><P
> HTML interpretation. In order to specify a random string, you
<SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>must</I
></SPAN
> include it in double quotes, and
<A
HREF="function.htmlspecialchars.html"
><B
CLASS="function"
>htmlspecialchars()</B
></A
> the whole value.
</P
></LI
><LI
><P
> URL: A URL consists of several parts. If you want your data to be
interpreted as one item, you <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>must</I
></SPAN
> encode it with
<A
HREF="function.urlencode.html"
><B
CLASS="function"
>urlencode()</B
></A
>.
</P
></LI
></UL
>
</P
><P
> <TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN103719"
></A
><P
><B
>Example 51-1. A hidden HTML form element</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="php"
><?php
echo "<input type=hidden value=\"" . htmlspecialchars($data) . "\">\n";
?></PRE
></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
>
<DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
It is wrong to <A
HREF="function.urlencode.html"
><B
CLASS="function"
>urlencode()</B
></A
>
<TT
CLASS="varname"
>$data</TT
>, because it's the browsers responsibility to
<A
HREF="function.urlencode.html"
><B
CLASS="function"
>urlencode()</B
></A
> the data. All popular browsers do that
correctly. Note that this will happen regardless of the method (i.e.,
GET or POST). You'll only notice this in case of GET request though,
because POST requests are usually hidden.
</P
></BLOCKQUOTE
></DIV
>
<TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN103727"
></A
><P
><B
>Example 51-2. Data to be edited by the user</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="php"
><?php
echo "<textarea name=mydata>\n";
echo htmlspecialchars($data)."\n";
echo "</textarea>";
?></PRE
></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
>
<DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
The data is shown in the browser as intended, because the browser will
interpret the HTML escaped symbols.
</P
><P
> Upon submitting, either via GET or POST, the data will be urlencoded
by the browser for transferring, and directly urldecoded by PHP. So in
the end, you don't need to do any urlencoding/urldecoding yourself,
everything is handled automagically.
</P
></BLOCKQUOTE
></DIV
>
<TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
CLASS="EXAMPLE"
><TR
><TD
><DIV
CLASS="example"
><A
NAME="AEN103733"
></A
><P
><B
>Example 51-3. In an URL</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="php"
><?php
echo "<a href=\"" . htmlspecialchars("/nextpage.php?stage=23&data=" .
urlencode($data)) . "\">\n";
?></PRE
></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
>
<DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
In fact you are faking a HTML GET request, therefore it's necessary to
manually <A
HREF="function.urlencode.html"
><B
CLASS="function"
>urlencode()</B
></A
> the data.
</P
></BLOCKQUOTE
></DIV
>
<DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
You need to <A
HREF="function.htmlspecialchars.html"
><B
CLASS="function"
>htmlspecialchars()</B
></A
> the whole URL, because the
URL occurs as value of an HTML-attribute. In this case, the browser
will first un-<A
HREF="function.htmlspecialchars.html"
><B
CLASS="function"
>htmlspecialchars()</B
></A
> the value, and then pass
the URL on. PHP will understand the URL correctly, because you
<B
CLASS="function"
>urlencoded()</B
> the data.
</P
><P
> You'll notice that the <TT
CLASS="literal"
>&</TT
> in the URL is replaced
by <TT
CLASS="literal"
>&amp;</TT
>. Although most browsers will recover
if you forget this, this isn't always possible. So even if your URL is
not dynamic, you <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>need</I
></SPAN
> to
<A
HREF="function.htmlspecialchars.html"
><B
CLASS="function"
>htmlspecialchars()</B
></A
> the URL.
</P
></BLOCKQUOTE
></DIV
>
</P
></DIV
></DIV
><DIV
CLASS="qandaentry"
><B
><DIV
CLASS="question"
><P
><A
NAME="faq.html.form-image"
></A
><B
>2. </B
>
I'm trying to use an <input type="image"> tag, but
the <TT
CLASS="varname"
>$foo.x</TT
> and <TT
CLASS="varname"
>$foo.y</TT
> variables
aren't available. <TT
CLASS="varname"
>$_GET['foo.x']</TT
> isn't existing
either. Where are they?
</P
></DIV
></B
><DIV
CLASS="answer"
><P
><B
> </B
>
When submitting a form, it is possible to use an image instead of
the standard submit button with a tag like:
<TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="html"
><input type="image" src="image.gif" name="foo"></PRE
></TD
></TR
></TABLE
>
When the user clicks somewhere on the image, the accompanying form
will be transmitted to the server with two additional variables:
<TT
CLASS="varname"
>foo.x</TT
> and <TT
CLASS="varname"
>foo.y</TT
>.
</P
><P
> Because <TT
CLASS="varname"
>foo.x</TT
> and <TT
CLASS="varname"
>foo.y</TT
> would
make invalid variable names in PHP, they are automagically converted to
<TT
CLASS="varname"
>foo_x</TT
> and <TT
CLASS="varname"
>foo_y</TT
>. That is, the
periods are replaced with underscores. So, you'd access these variables
like any other described within the section on retrieving
<A
HREF="language.variables.external.html"
>variables from outside of
PHP</A
>. For example, <TT
CLASS="varname"
>$_GET['foo_x']</TT
>.
</P
></DIV
></DIV
><DIV
CLASS="qandaentry"
><B
><DIV
CLASS="question"
><P
><A
NAME="faq.html.arrays"
></A
><B
>3. </B
>How do I create arrays in a HTML <form>?</P
></DIV
></B
><DIV
CLASS="answer"
><P
><B
> </B
>
To get your <form> result sent as an
<A
HREF="language.types.array.html"
>array</A
> to your PHP script
you name the <input>, <select> or <textarea>
elements like this:
<TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="html"
><input name="MyArray[]">
<input name="MyArray[]">
<input name="MyArray[]">
<input name="MyArray[]"></PRE
></TD
></TR
></TABLE
>
Notice the square brackets after the variable name, that's what
makes it an array. You can group the elements into different arrays
by assigning the same name to different elements:
<TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="html"
><input name="MyArray[]">
<input name="MyArray[]">
<input name="MyOtherArray[]">
<input name="MyOtherArray[]"></PRE
></TD
></TR
></TABLE
>
This produces two arrays, MyArray and MyOtherArray, that gets sent
to the PHP script. It's also possible to assign specific keys
to your arrays:
<TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="html"
><input name="AnotherArray[]">
<input name="AnotherArray[]">
<input name="AnotherArray[email]">
<input name="AnotherArray[phone]"></PRE
></TD
></TR
></TABLE
>
The AnotherArray array will now contain the keys 0, 1, email and phone.
</P
><P
> <DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>Note: </B
>
Specifying an arrays key is optional in HTML. If you do not specify
the keys, the array gets filled in the order the elements appear in
the form. Our first example will contain keys 0, 1, 2 and 3.
</P
></BLOCKQUOTE
></DIV
>
</P
><P
> See also
<A
HREF="ref.array.html"
>Array Functions</A
> and
<A
HREF="language.variables.external.html"
>Variables from outside PHP</A
>.
</P
></DIV
></DIV
><DIV
CLASS="qandaentry"
><B
><DIV
CLASS="question"
><P
><A
NAME="faq.html.select-multiple"
></A
><B
>4. </B
>
How do I get all the results from a select multiple HTML tag?
</P
></DIV
></B
><DIV
CLASS="answer"
><P
><B
> </B
>
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.
<TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="html"
><select name="var" multiple></PRE
></TD
></TR
></TABLE
>
Each selected option will arrive at the action handler as:
<TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="programlisting"
>var=option1
var=option2
var=option3</PRE
></TD
></TR
></TABLE
>
Each option will overwrite the contents of the previous
<TT
CLASS="varname"
>$var</TT
> variable. The solution is to use
PHP's "array from form element" feature. The following
should be used:
<TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="html"
><select name="var[]" multiple></PRE
></TD
></TR
></TABLE
>
This tells PHP to treat <TT
CLASS="varname"
>$var</TT
> as an array and
each assignment of a value to var[] adds an item to the array.
The first item becomes <TT
CLASS="varname"
>$var[0]</TT
>, the next
<TT
CLASS="varname"
>$var[1]</TT
>, etc. The <A
HREF="function.count.html"
><B
CLASS="function"
>count()</B
></A
>
function can be used to determine how many options were selected,
and the <A
HREF="function.sort.html"
><B
CLASS="function"
>sort()</B
></A
> function can be used to sort
the option array if necessary.
</P
><P
> Note that if you are using JavaScript the <TT
CLASS="literal"
>[]</TT
>
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, or enclose the variable name in single quotes and
use that as the index to the elements array, for example:
<TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
CELLPADDING="5"
><TR
><TD
><PRE
CLASS="programlisting"
>variable = documents.forms[0].elements['var[]'];</PRE
></TD
></TR
></TABLE
>
</P
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