�� 52. PHP and HTML

PHP and HTML interact a lot: PHP can generate HTML, and HTML can pass information to PHP.

1. What encoding/decoding do I need when I pass a value through a form/URL?
2. I'm trying to use an <input type="image"> tag, but the $foo.x and $foo.y variables aren't available. Where are they?
3. How do I create arrays in a HTML <form>?
4. How do I get all the results from a select multiple HTML tag?

1. What encoding/decoding do I need when I pass a value through a form/URL?

There are several stages for which encoding is important. Assuming that you have a string $data, which contains the string you want to pass on in a non-encoded way, these are the relevant stages:

HTML interpretation. In order to specify a random string, you must include it in double quotes, and htmlspecialchars the whole value.
URL: A URL consists of several parts. If you want your data to be interpreted as one item, you must encode it with urlencode().

�� 52-1. A hidden HTML form element
<?php echo "<input type=hidden value=\"" . htmlspecialchars($data) . "\">\n"; ?>

ע: It is wrong to urlencode() $data, because it's the browsers responsibility to urlencode() 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.

�� 52-2. Data to be edited by the user

<?php
    echo "<textarea name=mydata>\n";
    echo htmlspecialchars($data)."\n";
    echo "</textarea>";
?>

ע: The data is shown in the browser as intended, because the browser will interpret the HTML escaped symbols.
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.

�� 52-3. In an URL

<?php
    echo "<a href=\"" . htmlspecialchars("/nextpage.php?stage=23&data=" .
        urlencode($data)) . "\">\n";
?>

ע: In fact you are faking a HTML GET request, therefore it's necessary to manually urlencode() the data.

ע: You need to htmlspecialchars() the whole URL, because the URL occurs as value of an HTML-attribute. In this case, the browser will first un-htmlspecialchars() the value, and then pass the URL on. PHP will understand the URL correctly, because you urlencoded() the data.
You'll notice that the & in the URL is replaced by &. Although most browsers will recover if you forget this, this isn't always possible. So even if your URL is not dynamic, you need to htmlspecialchars() the URL.

2. I'm trying to use an <input type="image"> tag, but the $foo.x and $foo.y variables aren't available. Where are they?

When submitting a form, it is possible to use an image instead of the standard submit button with a tag like:
<input type="image" src="image.gif" name="foo">
When the user clicks somewhere on the image, the accompanying form will be transmitted to the server with two additional variables: foo.x and foo.y.

Because $foo.x and $foo.y are invalid variable names in PHP, they are automagically converted to $foo_x and $foo_y. That is, the periods are replaced with underscores.

3. How do I create arrays in a HTML <form>?

To get your <form> result sent as an array to your PHP script you name the <input>, <select> or <textarea> elements like this:
<input name="MyArray[]"> <input name="MyArray[]"> <input name="MyArray[]"> <input name="MyArray[]">
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:
<input name="MyArray[]"> <input name="MyArray[]"> <input name="MyOtherArray[]"> <input name="MyOtherArray[]">
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:
<input name="AnotherArray[]"> <input name="AnotherArray[]"> <input name="AnotherArray[email]"> <input name="AnotherArray[phone]">
The AnotherArray array will now contain the keys 0, 1, email and phone.

ע: 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.

4. 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 "array from form element" 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, or enclose the variable name in single quotes and use that as the index to the elements array, for example:
variable = documents.forms[0].elements['var[]'];

Take care when generating a select from an echo - the following does not work: echo "<select name=\"$name[]\" multiple size=$sz>"; The is because the [] os evaluated as part of an array expression. Instead do: echo "<select name=\"".$name."[]\" multiple size=$sz>";

I just did a script that generated an array from a form by creating the input tags using name=array[x] and it worked fine... if its not supposed to work... well it does. Just incase you were looking for confirmation.

Remember, the values of the listbox should be selected before they are transmitted. Of course, to the casual observer this is trival as hell. But: if you're working with multiple listboxes let's say for transferring values from one box to the other (anyone know a better way of updating a many-to-many relation?) this is easily overlooked. well.. okay... at least it happened to me. So: in this situation, make sure that there's a JavaScript that selects all values once the submit button is pressed.

Errors in previous posts: $name[] is not evaluated for presence "[" and "]" but because of "$" in the front what is absolutely wrong for general reasons. Don't be surprised. Sipmly, $anything is a variable. I think "[" and "]" iare valid for name atributes according to That's all folks, use arrays and prosper.

You can also use this to create multidimensional arrays: <input type="text" name="bob[]"> <input type="text" name="bob[1][]"> makes an array of: bob[0] = some text bob[1] = an array bob[1][0] = some text Fun stuff, very helpful in submitting an entire form and putting all the data into a single array rather than naming each element....

I think '[' and ']' are valid characters for name attributes. -> InputType of 'name' attribute is 'CDATA'(not 'NAME' type) -> about CDATA('name' attribute is not 'NAME' type!) ...CDATA is a sequence of characters from the document character set and may include character entities... --> about character entity references in HTML 4 ([ - &#91, ] - &#93)

I'm using an NT Server, IIS and mySQL. When processing posted variables, I kept getting the message on my browser; Warning: Use of undefined constant name - assumed 'name' in <script.php> The warning messages was created by using the code; $name1 = $_POST[name]; To stop this warning message, I used the code; $name1 = $_POST['name'];

How can I pass ALL the values from a multiple select list? Using <select name="myArray[]" ...> will only send the selected elements. Is there a way to pass every element? I can do it through javascript by setting all elements as selected and then submitting. But is there a better way?

To send all values from the multiple select, you must all select with a thing like this (javascript) : <form OnSubmit=" for (i=0; i<SelectArray.length; i++){ SelectArray.options[i].selected = true; } ">

To the gentleman who was having problems processing POST variables: $name1 = $_POST[name]; ...is always wrong, unless name is some constant you've defined. If you're looking for the form variable called name, you have to use 'name'. Read the manual under Basic Language Reference, where it says "Why is $foo[bar] wrong?" Incidentally, none of this has much to do with getting arrays from your POSTDATA, per se.

I've found that a neat trick is to do: <form onSubmit="selection.name=selection.name + '[]'"> That way you can still do form.selection, instead of form.elements['selection[]'] and still capture multiple variables.

Hi. I am new to PHP. I try to make PHP work with pws. Here is the problem I am facing. I create a text box in an HTML file and give it the name Comment. I type the comments into the box and call a php script file to insert the comments into mysql database. Normally, php engine would create a variable with the name $Comment. However, it seems it doesn't work in my examples because when I echo the $variable, it shows it is empty. What is going on? Any suggestion?

I am trying to pass a php string $temp in a applet argument. ex : DataSet1= <? $temp ?>; and if I do a view source, it shows this : DataSet1= ; And I know for a fact that $temp has indeed info in there... Does anybody know what's going on?


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