Name Example

The below form is used to submit your name to a PHP Script, the script will then handle and display the name in your browser.

The name attribute on the input elements is the name of the $_POST arrays in PHP.

<form action="action.php" method="post">
 <p>Your name: <input type="text" name="name"></p>
 <p>Your last name: <input type="text" name="last"></p>
 <p><input type="submit"></p>
</form>

The PHP Script would then be named action.php, and its content would be:

<p>Hello <?php echo $_POST['name'] . $_POST['last']; ?></p>

Regular Expression

Its important to validate input from users, to avoid security issues. One of the best way to do this, is to use a Regular Expression to get rid of special characters. So we add the following If statement to the code:

if ((preg_match("/^[a-zA-Z]{3,100}$/D", $_POST['name'])) && (preg_match("/^[a-zA-Z]{3,100}$/D", $_POST['last']))) {

  <p>Hello <?php echo $_POST['name'] . $_POST['last']; ?></p>

}

Above regular expression [a-zA-Z] allows the string to contain both the uppercase and lowercase characters A to Z, while the {3,100} part tells that the string must be between 3 to 100 characters in length.

Htmlspecialchars Function

Those who don't like regular expressions can use this function, this will automatically convert some characters with special meaning, to their HTML entities.

<p>Hello <?php echo htmlspecialchars($_POST['name']) . htmlspecialchars($_POST['last']); ?></p>

The posted data was accessed through the $_POST superglobal, which will contain all post data. You can also submit using the get method in your form, in that case you simply use the $_GET superglobal instead.

Radio Buttons

A few ways of getting the value of Radiobuttons in PHP.

Getting the value of radio buttons is actually easy, each input should have a name assigned through the name attribute, we will use this in the $_POST array of PHP. So if we got the below form:

<form action="action.php" method="post">
<div><input type="radio" name="state" value="Active" checked="checked"><label>Active</label></div>
<div><input type="radio" name="state" value="Inactive"><label>Inactive/Disabled</label></div>
</form>

The PHP code used to get the value of the radio buttons would be:

<?php

if ($_POST['state'] == 'Active'){
  /* Do stuff Here */
} else {
  /* If state was either inactive or not Selected */
}

?>

We can then make a choice based upon if the radio button was checked, and/or which one that where checked.

You can also use the isset function to check if a field was left empty, this is done like below:

<?php

if (isset($_POST['state']) {
/* A Radio button was Selected */
} else {
/* A Radio button was not Selected
   so we exit the script without action. */
  echo 'Please make a Choice!';
  exit();
}

?>

If the checkbox was left empty, we simply tell the user to make a choice, and exit the script without action.