Web Programming Step by Step, 2nd Edition
Lecture 7: Embedded PHP
Reading: 5.3 - 5.5
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Copyright 2012 Marty Stepp, Jessica Miller, and Victoria Kirst.
All rights reserved.
Any redistribution, reproduction, transmission, or storage of part
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5.2: PHP Basic Syntax
-
5.1: Server-Side Basics
-
5.2: PHP Basic Syntax
-
5.3: Embedded PHP
-
5.4: Advanced PHP Syntax
PHP syntax template
HTML content
<?php
PHP code
?>
HTML content
<?php
PHP code
?>
HTML content ...
- any contents of a
.php file between <?php and ?> are executed as PHP code
- all other contents are output as pure HTML
- can switch back and forth between HTML and PHP "modes"
$a = 3;
$b = 4;
$c = sqrt(pow($a, 2) + pow($b, 2));
math constants
M_PI
|
M_E
|
M_LN2
|
- the syntax for method calls, parameters, returns is the same as Java
int and float types
$a = 7 / 2;
$b = (int) $a;
$c = round($a);
$d = "123";
$e = (int) $d;
int for integers and float for reals- division between two
int values can produce a float
$favorite_food = "Ethiopian";
print $favorite_food[2];
- zero-based indexing using bracket notation
- string concatenation operator is
. (period), not +
5 + "2 turtle doves" produces 75 . "2 turtle doves" produces "52 turtle doves"
- can be specified with
"" or ''
Interpreted strings
$age = 16;
print "You are " . $age . " years old.\n";
print "You are $age years old.\n";
String functions
$name = "Stefanie Hatcher";
$length = strlen($name);
$cmp = strcmp($name, "Brian Le");
$index = strpos($name, "e");
$first = substr($name, 9, 5);
$name = strtoupper($name);
bool (Boolean) type
$feels_like_summer = FALSE;
$php_is_rad = TRUE;
$student_count = 217;
$nonzero = (bool) $student_count;
- the following values are considered to be
FALSE (all others are TRUE):
-
0 and 0.0
-
"", "0", and NULL (includes unset variables)
- arrays with 0 elements
- can cast to boolean using
(bool)
FALSE prints as an empty string (no output); TRUE prints as a 1
TRUE and FALSE keywords are case insensitive
5.3: Embedded PHP
-
5.1: Server-Side Basics
-
5.2: PHP Basic Syntax
-
5.3: Embedded PHP
-
5.4: Advanced PHP Syntax
Printing HTML tags in PHP = bad style
<?php
print "<!DOCTYPE html>\n";
print "<html>\n";
print " <head>\n";
print " <title>Geneva's web page</title>\n";
...
for ($i = 1; $i <= 10; $i++) {
print "<p class=\"count\"> I can count to $i! </p>\n";
}
?>
- printing HTML tags with
print statements is bad style and error-prone:
- must quote the HTML and escape special characters, e.g.
\"
- but without
print, how do we insert dynamic content into the page?
PHP expression blocks
<?= expression ?>
<h2> The answer is <?= 6 * 7 ?> </h2>
The answer is 42
-
PHP expression block: evaluates and embeds an expression's value into HTML
-
<?= expr ?> is equivalent to <?php print expr; ?>
Expression block example
<!DOCTYPE html>
<html>
<head><title>CSE 190 M: Embedded PHP</title></head>
<body>
<?php for ($i = 99; $i >= 1; $i--) { ?>
<p> <?= $i ?> bottles of beer on the wall, <br />
<?= $i ?> bottles of beer. <br />
Take one down, pass it around, <br />
<?= $i - 1 ?> bottles of beer on the wall. </p>
<?php } ?>
</body>
</html>
Common errors: unclosed braces, missing = sign
<body>
<p>Watch how high I can count:
<?php for ($i = 1; $i <= 10; $i++) { ?>
<? $i ?>
</p>
</body>
</html>
Complex expression blocks
<body>
<?php for ($i = 1; $i <= 3; $i++) { ?>
<h<?= $i ?>>This is a level <?= $i ?> heading.</h<?= $i ?>>
<?php } ?>
</body>
This is a level 1 heading.
This is a level 2 heading.
This is a level 3 heading.
- expression blocks can even go inside HTML tags and attributes
