View
1.845
Download
1
Category
Preview:
DESCRIPTION
Citation preview
Control Structures in PHP
Control Structures – if statements
if ($a > $b)
echo "a is bigger than b";
if ($a > $b)
{print "a is bigger than b";
$b = $a;}
if ($a > $b)
{print "a is bigger than b";}
else {print "a is NOT bigger than b";}
if ($a > $b)
{print "a is bigger than b";}
elseif ($a == $b)
{print "a is equal to b";}
else {print "a is smaller than b“;}
Example usage
Example<html><head><title>Your browser</title></head><body><h1>Your Browser</h1><p> <?php if( strstr($HTTP_USER_AGENT,"MSIE") ) { echo "You are using Internet Explorer"; }?>to view this page.</p></body></html>
strstr is a function which checks if its 2nd argument is a substring of its 1st
Control constructs -- looping
In PHP we have the following looping statements: while - loops through a block of code if and
as long as a specified condition is true do...while - loops through a block of code
once, and then repeats the loop as long as a special condition is true
for - loops through a block of code a specified number of times
foreach - loops through a block of code for each element in an array
Control constructs -- while
These are just like their counterparts in C $i = 1;
while ( $i <= 10 )
{ echo $i++; }
$i = 0;
do { print $i;} while ($i>0);
Control constructs -- for
These are just like their counterparts in Cfor ($i = 1; $i <= 10; $i++)
{ print $i;}
Control constructs -- foreach
These are similar their counterparts in Perl foreach(array_expression as $value)
statement
foreach(array_expression as $key => $value)
statement
<?php
$arr=array("one", "two", "three");
foreach ($arr as $value)
{echo “Number: " . $value . "<br />";}
?>
Jumping in and out of PHP mode
We can jump in and out of PHP mode even in the middle of a PHP block:
<?php
if(strstr($HTTP_USER_AGENT,"MSIE")) { ?> <p>You are using Internet Explorer</p> <?php } else { ?> <p>You are not using Internet Explorer</p> <?php } ?>
Instead of using an echo statement to print something, we jumped out of PHP mode.Note that the logical flow of the PHP remains intact
Only one of the HTML blocks will be sent to the user.
A FORM and its handler in one
<html><head><title>Application Handler</title></head><body><?phpif (! $_POST["surname"] or !$_POST["address"]){?>
<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>"><p>Your surname: <input type="text" name="surname"></p><p>Your address: <input type="text" name="address"></p><input button type="submit" value= "Please send me the brochure.">
</form><?php } else{
$sn = $_REQUEST['surname'];echo "<p>Thank you, $sn.</p>";$addr = $_REQUEST['address'];
echo "<p> We will write to you at $addr .</p>";} ?></body></html>
Finding out about your PHP environment
One of the many pre-defined PHP functions is phpinfo()
<html> <body> <h1>Your PHP Environment</h1><?php phpinfo(); ?> </body> </html>
In what follows, notice that mySQL support is enabled
Adding Comments to a PHP Script
Comments are nonprinting lines placed in code such as: The name of the script Your name and the date you created
the program Notes to yourself Instructions to future programmers
who might need to modify your work
Adding Comments to a PHP Script (continued)
Line comments hide a single line of code Add // or # before the text Choose and stick with version
Block comments hide multiple lines of code Add /* to the first line of code And */ after the last character in the
code
Example Comments<?php/*This line is part of the block comment.This line is also part of the block comment.*/echo (“<h1>Comments Example</h1>”); // Line comments
can followcode statements// This line comment takes up an entire line.# This is another way of creating a line comment./* This is another way of creating a block comment. */?>
Recommended