<?phpif (strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE') !== FALSE) {
echo 'You are using Internet Explorer.<br />';
}?>
Here we introduce a couple of new concepts. We have an
if statement.
If you are familiar with the basic syntax used by the C
language, this should look logical to you. Otherwise, you
should probably pick up an introductory PHP book and read the first
couple of chapters, or read the Language
Reference part of the manual.
The second concept we introduced was the strpos()
function call. strpos()
is a function built into
PHP which searches a string for another string. In this case we are
looking for 'MSIE' (so-called needle) inside
$_SERVER['HTTP_USER_AGENT'] (so-called
haystack). If
the needle is found inside the haystack, the function returns the
position
of the needle relative to the start of the haystack. Otherwise, it
returns FALSE. If it does not return FALSE,
the if expression evaluates to TRUE
and the code within its {braces} is executed. Otherwise, the code is
not
run. Feel free to create similar examples,
with if,
else, and other
functions such as strtoupper() and
strlen().
Each related manual page contains examples
too. If you are unsure how to use functions, you will want to read
both
the manual page on how
to read a
function definition and the section about
PHP functions.
