26.2 PHP
Arithmetic operators −
Assignment operators
Syntactical shortcuts Before being assigned values, variables have value undef
Constants − –
Named values define function
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<!-- Fig. 26.4: operators.php
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<!-- Demonstration of operators -->
-->
operators.php (1 of 3)
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<html xmlns = "http://www.w3.org/1999/xhtml"> <head> <title>Using arithmetic operators</title> </head>
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<body> <?php
Define constant VALUE.
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$a = 5;
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print( "The value of variable a is $a <br />" );
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// define constant VALUE
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define( "VALUE", 5 );
Add constant VALUE to variable $a.
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// add constant VALUE to variable $a
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$a = $a + VALUE;
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print( "Variable a after adding constant VALUE
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is $a <br />" );
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2
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// multiply variable $a by 2
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$a *= 2;
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print( "Multiplying variable a by 2 yields $a <br />" );
Multiply variable $a by two using the multiplication assignment operator *=.
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operators.php 50 Print if variable $a isTest lesswhether than 50.variable $a is less(2than of 3)
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// test if variable $a is less than 50
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if ( $a < 50 )
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print( "Variable a is less than 50 <br />" );
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// add 40 to variable $a
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$a += 40;
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print( "Variable a after
Add 40 to variable $a using the addition assignment operator +=. adding 40 is $a <br />" );
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// test if variable $a is 50 or less
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if ( $a < 51 )
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print( "Variable a is still 50 or less<br />" );
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// test if variable $a is between 50 and 100, inclusive
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elseif ( $a < 101 )
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print( "Variable a is now between 50 and 100,
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inclusive<br />" ); else print( "Variable a is now greater than 100 <br />" );
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3
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// print an uninitialized variable
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print( "Using a variable before initializing:
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$nothing <br />" );
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// add constant VALUE to an uninitialized variable
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$test = $num + VALUE;
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print( "An uninitialized variable plus constant
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VALUE yields $test <br />" );
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Print anAdd uninitialized variable $nothing ). constant VALUE to (an uninitialized an integer variable.
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// add a string to
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$str = "3 dollars";
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$a += $str;
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print( "Adding a string to variable a yields $a
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operators.php (3 of 3)
<br />" ); ?> </body>
Add a string to an integer.
65 </html>
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Fig. 26.4
26.2 PHP
Using PHPâ&#x20AC;&#x2122;s arithmetic operators.
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26.2 PHP
Keywords − Reserved for language – if…elseif…else
features
Arrays −
Group of related data
−
Elements
Name plus braces and index
Indices start at zero
function array function
– count –
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26.2 PHP
Arrays, cont. −
Built-in iterators
Maintain pointer to element currently referenced
• reset • key • next • foreach loops
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26.2 PHP PHP keywords and break case class continue default
do else elseif extends false
for foreach function global if
include list new not or
require return static switch this
true var virtual xor while
Fig. 26.5 PHP keywords.
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3 4
<!-- Fig. 26.6: arrays.php -->
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<!-- Array manipulation
arrays.php (1 of 3)
-->
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<html xmlns = "http://www.w3.org/1999/xhtml"> <head> <title>Array manipulation</title> </head>
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<body>
Create the array $first by assigning a value to an array element.
<?php
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// create array first
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print( "<strong>Creating the first array</strong>
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<br />" );
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$first[ 0 ] = "zero";
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$first[ 1 ] = Assign "one";
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a value to the array, omitting the index. for loop each elementâ&#x20AC;&#x2122;s index and value. $first[ 2 ] = Appends "two"; a Use newaelement to to theprint end out of the array. Function count returns the total number of elements in the $first[] = "three"; array.
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// print each elementâ&#x20AC;&#x2122;s index and value
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for ( $i = 0; $i < count( $first ); $i++ )
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print( "Element $i is $first[$i] <br />" );
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print( "<br /><strong>Creating the second array
Call function array to create an array that contains the arguments passed to it. Store the array in variable arrays.php array to create array$second second . (2 of 3) "zero", "one", "two", "three" );
</strong><br />" );
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// call function
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$second = array(
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for ( $i = 0; $i < count( $second ); $i++ )
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print( "Element $i is $second[$i] <br />" );
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print( "<br /><strong>Creating the third array </strong><br />" );
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// assign values to non-numerical indices
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$third[ "ArtTic" ] = 21;
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$third[ "LunaTic" ] = 18;
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$third[ "GalAnt" ] =
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Assign values to non-numerical indices in array $third. 23; Function reset sets the internal pointer to the first element of the array.
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// iterate through the array elements and print each
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// elementâ&#x20AC;&#x2122;s name and value
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for ( reset( $third ); $element = key( $third );
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next( $third ) )
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print( "$element is $third[$element] <br />" );
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Function key returns the index of the element which the internal pointer references. Function next moves the internal pointer to the next element.
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print( "<br /><strong>Creating the fourth array
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</strong><br />" );
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// call function array to create array fourth using
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// string indices
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$fourth = array(
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"January"
=> "first",
"February" => "second",
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"March"
=> "third",
"April"
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"May"
=> "fifth",
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"July"
=>
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"September" =>
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"November"
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);
=>
arrays.php (3 of 3) => "fourth",
Operator is used in function array to assign each "June" =>=> "sixth", a string index. The value to the left of the "seventh",element "August" => "eighth", is the index, and the value to the right is "ninth", operator "October" => array "tenth", the elementâ&#x20AC;&#x2122;s=>value. "eleventh","December" "twelfth"
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// print each elementâ&#x20AC;&#x2122;s name and value
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foreach ( $fourth as $element => $value )
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print( "$element is the $value month <br />" );
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?>
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</body>
68 </html>
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Fig. 26.6
Array manipulation.
26.2 PHP
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