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Using Forms
Using forms in a web based application is very common. Most forms are used
to gather information like in a signup form, survey / polling, guestbook,
etc.
A form can have the method set as post or
get. When using a form with method="post"
you can use $_POST to access the form values.
And when the form is using method="get"
you can use $_GET to access the values. The $_REQUEST
superglobal can be used to to access form values with method="post"
and method="get" but it is recommended
to use $_POST or $_GET
instead so you will know from what method did the values come from.
Here is an example of HTML form :
<form method="post" action="<?php
echo $_SERVER['PHP_SELF'];?>">
Name : <input name="username" type="text"><br>
Password : <input name="password" type="password"><br>
<input name="send" type="submit" value="Send!">
</form>
The form above use $_SERVER['PHP_SELF'] as
the action value. It is not required for the form to perform correctly but
it's considered good programming practice to use it.
Below is the PHP code used to access form values :
<?php
if(isset($_POST['send']))
{
echo "Accessing username using POST : " . $_POST['username']
. "<br>";
echo "Accessing username using REQUEST : " .
$_REQUEST['username']
. "<br>";
$password = $_POST['password'];
echo "Password is $password";
}
?>
The if statement is used to check if the send
variable is set. If it is set then the form must have been submitted. The
script then print the value of username using
$_POST and $_REQUEST
Using Array As Form Values
Take a look at the code example below. The form have five input with the
same name, language[]. Using the same input name
is common for checkboxes or radio buttons.
<form method="post" action="<?php echo
$_SERVER['PHP_SELF'];?>">
Select the programming languages you can use<br>
<input name="language[]" type="checkbox"
value="C++">
C++<br>
<input name="language[]" type="checkbox"
value="Java">
Java<br>
<input name="language[]" type="checkbox"
value="PHP">
PHP<br>
<input name="language[]" type="checkbox"
value="ASP">
ASP<br>
<input name="language[]" type="checkbox"
value="Delphi">
Delphi<br>
<input name="send" type="submit" id="send"
value="Send!">
</form>
The PHP code below print the value of language
after the form is submitted.
Try checking and unchecking the options to see the effect.
<?php
if(isset($_POST['language']))
{
$language = $_POST['language'];
$n = count($language);
$i = 0;
echo "The languages you selected are \r\n" .
"<ol>";
while ($i < $n)
{
echo "<li>{$language[$i]}</li>
\r\n";
$i++;
}
echo "</ol>";
}
?>
From the above code you will notice that $language
is an array. This is because in the form code language
is repeated several times. When you specify the same input name in a form,
PHP will treat it as an array.
There is one important issue you should know when using forms, that is form
validation. The code above does not check whether the input is correct such
as checking if the user is entering any value into the textbox or is the user
selecting any checkboxes. This is actually a bad practice because you should
never put a web form without any validation.
That's it. You just completed the
basics of PHP programming.
As is said earlier if you haven't got the PHP manual you should download
it now from php.net. You
can find lots of interesting (and important) stuff in it. You can get the
manual in various format but I recommend that you get the compiled
HTML (CHM) version. It's easier to read plus it has search capability
and loads of user contributed notes, very useful. |
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