Now that you've got the basics of PHP variables and operators down, the second article in this series takes a look at PHP's form-processing capabilities, and introduces you to the comparison and logical operators and the "if-else" and "switch" family of conditional statements.
In PHP, the simplest form of conditional statement is the "if" statement, which looks something like this:
if (condition)
{
do this!
}
The "condition" here is a conditional expression, which
evaluates to either true or false. If the statement evaluates to true, all PHP code within the curly braces is executed; if not, the code within the curly braces is skipped and the lines following the "if" construct are executed.
Let's show you how the "if" statement works by adding a little user authentication to the "login.php4" script above, such that access will be granted only when the user enters the name "neo".
<html>
<head>
<basefont face="Arial">
</head>
<body>
<center>
<?
// check name and print appropriate message
if ($name == "neo")
{
?>
<font face="Arial" size="-1">
Welcome to the Matrix, Neo.
<p>
May The Force be with you...oops, wrong movie!
</font>
<?
}
?>
<?
// if password is wrong
if ($name != "neo")
{
?>
<font face="Arial" size="-1">
I wonder if you've heard of Shakespeare, <? echo $name; ?>.
<p>
He postulated that a rose by any other name would smell just as sweet.
<p>
Unfortunately for you, I disagree. Access denied.
</font>
<?
}
?>
</center>
</body>
</html>
In this case, the two "if" statements present an appropriate
message, depending on whether or not the right password was entered. Of course, PHP also lets you "nest" conditional statements - for example, this is perfectly valid PHP code:
<?
if ($day == "Thursday")
{
if ($time == "12")
{
if ($place == "Italy")
{
$lunch = "pasta";
}
}
}
?>
