introduction to php and mysql kirkwood center for continuing education by fred mcclurg,...
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Introduction Introduction toto
PHP and PHP and MySQLMySQL
Kirkwood Center for Kirkwood Center for Continuing EducationContinuing Education
By Fred McClurg, [email protected]
© Copyright 2010, All Rights Reserved 1
Chapter Chapter ThreeThree
PHP FundamentalsPHP Fundamentals
http://webcert.kirkwood.edu/~fmcclurg/courses/php/slides/chapter03.ppt
2
PHP Home Page (excellent):http://www.php.net
PHP Manual:http://www.php.net/manual/en/
PHP Tutorial:http://www.w3schools.com/php/
PHP Manual Search (Firefox plugin):https://addons.mozilla.org/en-US/firefox/addon/8984
PHP Cookbook (762 page book):http://books.google.com/books?id=P1wJRrE8KjYC
PHP ReferencesPHP References
3
Description: Output much information regarding the PHP server
<?php phpinfo();
?>
Or ...
<?php phpinfo(); ?>
Your First PHP ProgramYour First PHP Program
4
Step One: Write HTML source “helloWorld.html”
<html>
<head>
<title>
Hello World!
</title>
</head>
<body>
<p> Hello World! </p>
<p>
Does anybody really
know what time it is?
</p>
</body>
</html>
Getting HTML to say, “Hello Getting HTML to say, “Hello World”World”
5
Step Two: Modify file “helloWorld.html” by inserting PHP code and renaming “helloWorld.php”
<html> <head> <title> Hello World! </title> </head>
<body> <p> Hello World! </p> <p> Current time:<?php echo date('r');?> </p> </body></html>
Note: A semi-colon ends each code statement.
Getting PHP to say, “Hello Getting PHP to say, “Hello World”World”
6
Defined: Comments are a method of documenting information inside the source code.
Note: Unlike JavaScript, PHP comments and code are not displayed in the HTML source. Only HTML comments and tags are displayed when performing a “view source” in the browser.
PHP CommentsPHP Comments
7
Defined: The double slash “//” is used to start a comment that continues to the end of the line.
Example:
<!-- HTML Comment -->
<?php // C++ like, single line comment
echo "I don't "; // can be placed at echo "know why "; // end of statement?>
Slash Slash (//) CommentsSlash Slash (//) Comments
8
Defined: The crunch symbol “#” (aka number, pound, hash, sharp, hex, tic-tac-toe sign) is used to begin a comment to the end of the line.
Examples:
<!-- HTML Comment -->
<?php # shell like, single line comment
echo "you say "; # also be placed echo "goodbye "; # at statement end?>
Crunch (#) CommentsCrunch (#) Comments
9
Defined: The symbols “/*” is used to begin a comment block and the symbols “*/” is used to end that block.
Examples:
<!-- HTML Comment -->
<?php /* C like, single line comments */
/* C like, multiple line comments spanning more than one line */
echo "I say "; /* use caution at echo "hello!"; statement end */?>
Slash Splat & Splat Slash Slash Splat & Splat Slash CommentsComments
10
Defined: The symbol “/**” denotes the beginning and the symbol “*/” denotes the end of a Doxygen comment block.
Example:
<!-- HTML Comment -->
<?php /** * @brief Javadoc like documentation * via doxygen commands (tags) * @see http://www.doxygen.nl */?>
Note: Doxygen is an auto documentation generation tool similar to “javadoc”. It supports a number of languages including PHP, C++, Python, Java. and JavaScript. For more information: www.doxygen.org or http://www.stack.nl/~dimitri/doxygen/
Slash Splat Splat Doxygen Slash Splat Splat Doxygen CommentsComments
11
Discussion: Nested comments can have unexpected consequences and are often the cause errors.
Example:
<?php // echo "Goodbye"; /* nesting permitted */
/* * echo "Goodbye"; // nesting permitted */
/* * echo "Goodbye"; /* results in error! */ */?>
Nested CommentsNested Comments
12
Syntax:$varName = constantOrExpression;
Rules:1. Dollar sign ($) must be the first character.
2. The second character must be a letter or underscore “_” (not a numeral).
3. Variable names contain only alphanumeric or underscore characters.
4. Variables are case sensitive. The following represent completely different variables:
$variableName;$variablename;$VariableName;
Variable RulesVariable Rules
15
Description:PHP creates the variable data type based on the value assigned (no worries mate!)
Example:$misc = 1; // integer$misc = "Davey"; // string$misc = 'Goliath'; // str$misc = 2.7182818; // float
Note: PHP is a weakly-typed (dynamically-typed) language
Variable TypesVariable Types
16
Description:Variables declared within the same block, have the same scope
Example:<body> <?php $warCry = "Cowabunga"; ?>
<!-- HTML Code Here --> <b>The war cry is:</b>
<?php echo $warCry; ?></body>
Variable Scope
17
Purpose:Allows the value of a variable to be placed within a string (variable expansion).
Example:<?php $hello = "Greetings Earthling!";
echo "He said, \"$hello\" <br />"; echo "Variable is \$hello <br />"; echo "Have you read,
Pilgrim's Progress? <br />"; echo "\nOne\nTwo\nThree";
?>
Double Quoted Strings Double Quoted Strings """"
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Definition: Placing a backslash (\) in front of certain characters gives them special meaning.
Escaped “Special” CharactersEscaped “Special” Characters
Character Definition
\n Newline
\t Tab
\$ Dollar Sign
\" Double Quote
\' Single Quote
\\ Backslash20
Purpose: Disables the expansion of variables and all characters except escaped single quotes (\').
Example:<?php
$hello = 'Greetings Earthling!'; echo 'He said, \"$hello\" <br
/>'; echo 'I said, \$hello <br />'; echo 'Pilgrim\'s Progress <br
/>'; echo '\nOne\nTwo\nThree';
?>
Single Quoted Strings Single Quoted Strings ''''
21
Definition: The dot character (.) is used for combining one or more text strings and variables.
Example:<?php $triad = "Faith " . "Hope "; $triad .= "Love"; // append love echo $triad . "<br />";
$count = 70 * 7; $forgiveness = "Forgive " . $count . " times"; echo $forgiveness;?>
ConcatenationConcatenation
23
Description: Unary operators take one operand.
Examples:$x = - $x; // negation operator$x = -1 * $x; // equivalent code$x++; // increment (postfix)--$x; // decrement (prefix)
Unary OperatorsUnary Operators
28
Discussion: Binary operators combine two expressions into a result (e.g. +, -, *, /).
Example:
$result = $x + $y;
Binary OperatorsBinary Operators
operandoperator
operand
expression
statement 29
Example:$a = 4; $b = 2;
Mathematical OperatorsMathematical Operators
Op. Name Type Definition Example Ans.
- Negation Unary Opposite of $a -$a -4
+ Addition Binary Sum of $a and $b $a + $b 6
- Subtraction Binary Difference of $a and $b $a - $b 2
* Multiplication Binary Product of $a and $b $a * $b 8
/ Division Binary Quotient of $a and $b $a / $b 2
% Modulus Binary Remainder of $a / $b $a % $b 0 32
Defined: Modulo is the integer remainder returned from a division
Discussion: It is often used for determining an evenly divisible multiple
Example:<?php $count = 15; $multiple = $count % 5;
if ($multiple == 0) { printf( "%d is a multiple of five", $count ); }?>
Modulo OperatorModulo Operator
33
Discussion: Assignment operators provide an abbreviated syntax for operations that are performed frequently. They are used when a variable is combined with an arithmetic operation and then the results are assigned back to that original variable.
Example:<?php $a = $b = 4; // multiple assignments
$a = $a + 2; // result: $a = 6 printf( "\$a = %d<br />", $a );
$b += 2; // result: $b = 6 echo( "\$b = $b<br />" );?>
Assignment Operator ExampleAssignment Operator Example
34
Example:$x = 4; // for every case below
Assignment Operators ListedAssignment Operators Listed
Assignment Operator
Name Equivalent Statement
Result
$x += 2; Addition $x = $x + 2; 6
$x -= 2; Subtraction $x = $x - 2; 2
$x *= 2; Multiplication $x = $x * 2; 8
$x /= 2; Division $x = $x / 2; 2
$x %= 2; Modulus $x = $x % 2; 0
$x .= 2; Concatenation $x = $x . 2; "42"35
Discussion: A commonly performed operation is to add one to a variable. PHP also has abbreviated syntax for this operation.
Example:
<?php $pre = $post = 4;
++$pre; // prefix increment printf( "\$pre = %d<br />", $pre );
$post++; // postfix increment printf( "\$post = %d<br />", $post );?>
Increment OperatorIncrement Operator
36
Discussion: Another commonly performed operation is to subtract one from a variable. PHP has an abbreviated syntax for this as well.
Example:
<?php $pre = $post = 4;
--$pre; // prefix decrement printf( "\$pre = %d<br />", $pre );
$post--; // postfix decrement printf( "\$post = %d<br />", $post );?>
Decrement OperatorDecrement Operator
37
Discussion: The main difference between the prefix and postfix operators is the order the arithmetic operation is performed in relation to the assignment.
Prefix (e.g. ++$var) order of operations:1. Arithmetic2. Assignment
Postfix (e.g. $var++) order of operations:1. Assignment2. Arithmetic
Prefix and Postfix ContrastedPrefix and Postfix Contrasted
38
Examples:// initialize for every statement$a = $b = 4;
// prefix operators$a = ++$b; // $a=5 $b=5$a = --$b; // $a=3 $b=3
// postfix operator (side effects)$a = $b++; // $a=4 $b=5$a = $b--; // $a=4 $b=3
Note: Because of the likelihood of introducing errors, Best Practices or Style Guidelines may mandate that only prefix operators be used. Other standards may permit either postfix or prefix but only as a standalone statement and not used in an assignment.
Prefix and Postfix ExamplesPrefix and Postfix Examples
39
Description: PHP performs automatic data type conversions between strings, integers and floats.
Examples:$value = "10" * "10"; // 100$value = "3.14" / 2; // 1.57$value = "Fred" * "McClurg"; // 0$value = "Me" . 2; // Me2
Note: Automatic data type conversion is called “implicit casting”
Data Type ConversionData Type Conversion
40
Description: Variables can be forced (or cast) to a specific type.
Cast Types :(int) or (integer)(bool) or (boolean)(float), (double), or (real)(string)
Examples:$value = (int) 3.95; // truncate decimal$value = (bool) -1; // TRUE$value = (float) 3; // 3.0
// round to nearest integer$value = (int)($number + 0.5);
Type CastingType Casting
41
Description: Some operators have a higher order of precedence which means they are processed first in an expression
Examples:echo 2 + 4 * 2; // 10echo (2 + 4) * 2; // 12
Note: See Chapter 4, page 65 & 66 for complete precedence table.
Order of PrecedenceOrder of Precedence
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to be to be continued ...continued ...
http://webcert.kirkwood.edu/~fmcclurg/courses/php/slides/chapter04a.conditions.ppt