JV’s Power Tips for PHP (2)

JV’s Power Tips for PHP (2) - The Problem
(Page 2 of 7 )

We all want to get things done and there are many ways to skin a cat. For example: Imagine you were writing a live chat script and you wanted to give the user the option of formatting each submission with any combination of Bold, Italic, Underlined and/or Strike Through. Here is an example HTML form for such a script:

<form method=post action=my_script.php>
<input type=text name=chat>
<input type=checkbox name=bold value=1>
<input type=checkbox name=italic value=1>
<input type=checkbox name=underline value=1>
<input type=checkbox name=strike value=1>
<input type=submit>
</form>

Since this form has the action of post we will be evaluating the following variables:

$_POST['chat']
$_POST['bold']
$_POST['italic']
$_POST['underline']
$_POST['strike']

At its most basic we can test if the user has selected bold by doing this:

<?php

  if ( $_POST['bold'] )
  {
    echo "The user selected bold";
  }

?>

Just in case you don't know why this works. It is because if the bold checkbox was selected, then the value of 1 will be sent to PHP (within the variable $_POST['bold'])., but if the bold checkbox was not selected then the variable $_POST['bold'] will not be sent to PHP at all.

Furthermore, in PHP you are able to put a single variable into an if statement. The if statement will then evaluate the contents of the variable. It will evaluate to false under the following conditions:

1. The variable does not exist
2. The variable exists with a value of nothing
3. The variable exists with a value of 0
4. The variable exists with a boolean value of false
5. The variable exists with a value of NULL

It will evaluate to true under the following conditions:

1. The variable exists and has ANY value except empty, 0, NULL or false.

You can also evaluate an assignment within an if statement. Like so:

<?php
  $i_am_false = false;

  if ( $make_me_false = $i_am_false )
  {
    echo "This will never be output!";
  }
  else
  {
    echo ‘Because $make_me_false was assigned the value of false';
  }
?>

You can also put an array or an object within an if statement.

<?php

  if ( $my_object )
  {
    echo "My object exists!!";
  }

  if ( $my_array )
  {
    echo "My array exists!!";
  }

?>
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