<?php
	$var = 'Hello Im a variable.';
 
	function makeBold( $text ) //The variable inside our makeBold fucntion $text, does not have to be a variable called
				   //$text when we run the function. It is just showing you where a variable or string should
				   //go so that it can be used inside the function.
	{
		$var = '<b>' . $text . '</b>';
		//Here we just set a variable $var inside our function, notice we already
		//have a variable called var in the first line of out code? it will not overwrite it.
		//variables made inside the function are used only inside the function that they were.
		//made in. 
 
		return $var;
		//return $var is the last part to this function and will output whatever $var may be to the page
		//once the function has been used within it.
	}
 
 
	$string = 'Here I have a different variable name and I would like the string it carries to be bold';
 
 
	makeBold( $string ); //Now this is where you may not understand it. When we created our function the variable 
			     //inside the brackets said $text and weve just put a variable called $string inside there!
			     //Do not fear this was intentional, I promise. The $text variable in the brackets when we created our
			     //function was only meant to show where the variable or string would be going once we put
			     //our function to use.
 
	echo '<br />';//dont want out text all bunched up now do we :)
 
	makeBold( 'I would like to be bold please' ); //you can also enter just a string inside the brackets of our function
						      //the string will replace the variable $text when we created our function
						      //if that helps you understand it better.
 
	echo '<br />';//dont want out text all bunched up now do we :)
 
	echo $var; //Finally we echo the variable we created before we created the function just to show that 
		   //a variable with the same name inside the function will not overwrite it.
?>

<?php
$var = 10;
$var2 = 11;
$var3 = 12;
 
$var = $var / 5 + 1 * 2;
echo $var.'<br />';
 
$var2 = $var2 / 5 + 1 * 2;
echo $var.'<br />';
 
$var2 = $var2 / 5 + 1 * 2;
echo $var.'<br />';
?>

<?php
function math( $var ){
$var = $var / 5 + 1 * 2;
return $var.'<br />';
}
math( '10' );
math( '11' );
math( '12' );
?>

<?php
 
    if ( isset( $_SESSION['name'] ) )
    {
        echo 'Your name is:<br />'.
              $_SESSION['name'];
    }
    else
    {
        $_SESSION['name'] = $_GET['name'];
        echo 'Session set as: '. $_GET['name'];
    }
 
 
?>

<?php
 
function clean ( $string )
{
    $malicious = array( 'javascript' , 'script>' , 'style>' , 'meta>' );
    $string    = str_replace( $malicious , '' , $string );
    $string    = htmlspecialchars( mysql_real_escape_string( $string ) );
    return $string;
}
 
    if ( isset( $_SESSION['name'] ) )
    {
        echo 'Your name is:<br />'.
              $_SESSION['name'];
    }
    else
    {
        $_SESSION['name'] = clean( $_GET['name'] );
        echo 'Session set as: '. $_GET['name'];
    }
 
 
?>