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php app development 1

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php app development 1

  1. 1. Web Scripting using PHP
  2. 2. Web Scripting using PHP Server side scripting
  3. 3. So what is a Server Side Scripting Language? • Programming language code embedded into a web page PERL PHP PYTHON ASP
  4. 4. So what is a Server Side Scripting Language? • Programming language code embedded into a web page PERL PHP PYTHON ASP
  5. 5. Different ways of scripting the Web • Programming language code embedded into a web page No scripting (plain markup) Client Side scripting Ser ver Side scripting Combination of the above (AJAX)
  6. 6. No Scripting example - how it works... User on a machine somewhere Ser ver machine
  7. 7. Being more specific...
  8. 8. Web Browser soft ware
  9. 9. Web ser ver soft ware
  10. 10. User types in a URL for a page with no programming code inside
  11. 11. User types in a URL for a page with no programming code inside Uniform Resource Locator
  12. 12. Request is sent to ser ver using HTTP
  13. 13. Request is sent to ser ver using HTTP Hypertext Transfer Protocol
  14. 14. Ser ver soft ware finds the page
  15. 15. Page is sent back, using HTTP
  16. 16. Browser renders / displays the page
  17. 17. Server Side scripting
  18. 18. User types in a URL for a page with PHP code inside
  19. 19. Request is sent to ser ver using HTTP
  20. 20. Ser ver soft ware finds the page
  21. 21. Ser ver side code is executed
  22. 22. Page is sent back, using HTTP
  23. 23. Browser renders / displays the page
  24. 24. Server side scripting languages • Executes in the ser ver • Before the page is sent from server to browser • Ser ver side code is not visible in the client • Ser ver side code can access resources on the server side
  25. 25. Browser Web ser ver Database ser ver
  26. 26. How many items in stock?
  27. 27. HTTP request
  28. 28. Web ser ver executes code
  29. 29. Web ser ver executes code Queries database ser ver
  30. 30. Result sent back
  31. 31. HTML generated
  32. 32. HTTP response
  33. 33. Answer displayed
  34. 34. So why PHP? PERL PHP PYTHON ASP
  35. 35. PHP usage ... • Source: PHP programming 2nd Ed.
  36. 36. PHP compared to others ... • Source: www.securityspace.com
  37. 37. Books - core syntax Programming PHP, Second Edition PHP in a Nutshell By Kevin Tatroe, Rasmus Lerdorf, By Paul Hudson Peter MacIntyre First Edition October 2005 Second Edition April 2006 ** Recommended
  38. 38. Books - learning / tutorial based Learning PHP 5 Learning PHP and MySQL By David Sklar By Michele Davis, Jon Phillips First Edition June 2004 First Edition June 2006
  39. 39. Other texts.. • There are other publishers / texts (trade books) • Look for books that cover PHP 5 • Open source, server side languages can rapidly develop • Features added or deprecated rapidly
  40. 40. PHP development PHP 5 PHP 4 PHP 3 PHP 1 • 5 versions in 10 years
  41. 41. Language basics
  42. 42. Language basics • Embedding PHP in Web pages • Whitespace and Line breaks • Statements and semicolons • Comments • Literals / names • Identifiers • Keywords • Data types
  43. 43. Language basics • Embedding PHP in Web pages • Whitespace and Line breaks • Statements and semicolons • Comments • Literals / names • Identifiers • Keywords • Data types Much of this material is explained in PHP programming 2nd Ed. Chap 1 & 2
  44. 44. Embedding PHP in web pages Use <?php and ?> to <?php surround the php code statement; statement; statement ?>
  45. 45. Embedding PHP in web pages <?php statement;statement; statement; statement; statement;statement; ?> In general whitespace doesn’t matter Use indenting and separate lines to create readable code
  46. 46. The legendary Hello World program <!DOCTYPE HTML PUBLIC "-//W3C/DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>This is the first PHP program</title> </head> <body> <p> <?php print "Hello World!"; ?> </p> </body> </html>
  47. 47. The legendary Hello World program <!DOCTYPE HTML PUBLIC "-//W3C/DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>This is the first PHP program</title> </head> <body> <p> <?php print "Hello World!"; ?> </p> </body> </html>
  48. 48. The legendary Hello World program <!DOCTYPE HTML PUBLIC "-//W3C/DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>This is the first PHP program</title> </head> <body> <p> print sends a sequence of <?php print "Hello World!"; characters to the output ?> </p> The sequence here is </body> indicated by start and </html> end quotes
  49. 49. PHP can be put ‘ nywhere’.. a All the php blocks are processed <html> <?php ... ?> before the page is sent <head> <?php ... ?> <title>... <?php ... ?> ...</title> </head> <body> <p> <?php ... ?> </p> </body> </html>
  50. 50. PHP can be put ‘ nywhere’.. but works in sequence a <html> <?php ... ?> Starting at the top <head> <?php ... ?> <title>... <?php ... ?> ...</title> </head> <body> <p> <?php ... ?> Working down to the bottom </p> </body> </html>
  51. 51. Statements and semicolons Use ; to separate <?php statements statement; statement; statement; ?>
  52. 52. All of these would work the same way... <?php statement; statement;statement ?> <?php statement; statement;statement; ?> <?php statement; statement; This is the best way of statement; laying the code out ?>
  53. 53. Comments Many different ways to add comments Comment Source Action // C++ Comments to EOL # Unix shell scripting Comments to EOL /* and */ C Comments out a block
  54. 54. Comments <?php php statement; // A comment here php statement; # Another comment here /* A series of lines with comments ignored by the PHP processor */ php statement; ?>
  55. 55. Comments <?php php statement; // A comment here php statement; # Another comment here /* A series of lines with comments ignored by the PHP processor */ php statement; ?> Everything in red is ignored by the PHP interpreter
  56. 56. Language basics • Embedding PHP in Web pages • Whitespace and Line breaks • Statements and semicolons • Comments • Literals / names • Identifiers • Keywords • Data types
  57. 57. Language basics • Embedding PHP in Web pages ✔ • Whitespace and Line breaks ✔ • Statements and semicolons ✔ • Comments ✔ • Literals / names • Identifiers • Keywords • Data types
  58. 58. Literals A data value that appears directly in the program 2001 An integer 0xFE Hexadecimal number 1.4142 Float “Hello World” String ‘Hi’ String true Bool null built in ‘no value’ symbol
  59. 59. Identifiers Identifiers (or names) in PHP must - Begin with an ASCII letter (uppercase or lowercase) or begin with the underscore character _ or any character bet ween ASCII 0x7F to 0xFF followed by any of these characters and the digits 0-9
  60. 60. Variables Variables in PHP are identifiers prefixed by $ $bill $value_count $anothervalue3 Valid $THIS_IS_NOT_A_GOOD_IDEA $_underscore $not valid Invalid $[ $3wa
  61. 61. Case sensitivity - names we define are case sensitive $value Three different names $VALUE $vaLUE
  62. 62. Variables We use variables for items of data that will change as the program runs Choose a sensible name and have as many as you like $total_income $bill $salary $month $total $percentage_increase
  63. 63. Variables When we declare a variable, a space is reserved and labelled for that item (in memory) $bill $bill
  64. 64. Variables To give it a value, use the equals sign $bill $bill
  65. 65. Variables To give it a value, use the equals sign $bill = 42 $bill
  66. 66. Variables To give it a value, use the equals sign $bill = 42 42 $bill
  67. 67. Variables To give it a value, use the equals sign $bill $bill
  68. 68. Variables To give it a value, use the equals sign $bill = 57.98 $bill
  69. 69. Variables To give it a value, use the equals sign $bill = 57.98 57.98 $bill
  70. 70. Variables To give it a value, use the equals sign $bill $bill
  71. 71. Variables To give it a value, use the equals sign $bill = “No payment” $bill
  72. 72. Variables To give it a value, use the equals sign $bill = “No payment” “No payment” $bill
  73. 73. Variables If a value is changed, the old value is over written $bill $bill
  74. 74. Variables If a value is changed, the old value is over written $bill = 42; $bill
  75. 75. Variables If a value is changed, the old value is over written $bill = 42; 42 $bill
  76. 76. Variables If a value is changed, the old value is over written $bill = 42; 42 $bill = 58; $bill
  77. 77. Variables If a value is changed, the old value is over written $bill = 42; 58 $bill = 58; $bill
  78. 78. Variables Sometimes we use the old value to recalculate the new value $bill $bill
  79. 79. Variables Sometimes we use the old value to recalculate the new value $bill = 42; $bill
  80. 80. Variables Sometimes we use the old value to recalculate the new value $bill = 42; 42 $bill
  81. 81. Variables Sometimes we use the old value to recalculate the new value $bill = 42; 42 $bill = $bill*2 ; $bill
  82. 82. Variables Sometimes we use the old value to recalculate the new value $bill = 42; 84 $bill = $bill*2 ; $bill
  83. 83. Variables Some languages are very strict about what kinds of data are stored in variables - PHP doesn’t care $bill=42; Stores an integer $bill=42; $bill=”Now its a string”; print $bull;
  84. 84. Variables Some languages are very strict about what kinds of data are stored in variables - PHP doesn’t care $bill=42; Stores an integer $bill=42; Over writes with a string $bill=”Now its a string”; print $bull;
  85. 85. Variables Some languages are very strict about what kinds of data are stored in variables - PHP doesn’t care $bill=42; Stores an integer $bill=42; Over writes with a string $bill=”Now its a string”; Whoops - made a mistake print $bull; but it still works
  86. 86. Variables Some languages are very strict about what kinds of data are stored in variables - PHP doesn’t care $bill=42; Stores an integer $bill=42; Over writes with a string $bill=”Now its a string”; Whoops - made a mistake print $bull; but it still works
  87. 87. Keywords _CLASS_ _ Declare extends print( ) _ _FILE_ _ Default final private Reserved by _ _FUNCTION_ _ die( ) for protected the language _ _LINE_ _ Do foreach public for core _ _METHOD_ _ echo( ) function require( ) Else global functionality Abstract And elseif if require_once( ) array( ) empty( ) implements return( ) As enddeclare include( ) static Break endfor include_once( ) switch Also - can’t Case catch endforeach interface tHRow endif isset( ) use a built in cfunction endswitch list( ) TRy unset( ) function Class endwhile new use clone name as a Const eval( ) old_function var exception Or variable Continue exit( ) php_user_filter while xor
  88. 88. Data types PHP provides 8 types scalar (single-value) compound integers arrays floating-point objects string booleans Two are special - resource and NULL
  89. 89. Integers Whole numbers - range depends on the C compiler that PHP was made in (compiled in) Typically +2,147,483,647 to -2,147,483,647 Octal 0755 Hexadecimal 0xFF Larger integers get converted to floats automatically
  90. 90. Floating-Point Numbers Real numbers - again range is implementation specific Typically 1.7E-308 to 1.7E+308 with 15 digits of accuracy Examples 3.14, 0.017, -7.1, 0.314E1, 17.0E-3
  91. 91. Strings Delimited by either single or double quotes ‘here is a string’ “here is another string”
  92. 92. Strings - single quotes You can use single quotes to enclose double quotes $outputstring=‘He then said “Goodbye” and left’; Useful for easily printing HTML attributes $outputstring=‘<a href=”http:/www.bbc.co.uk”>BBC</a>’;
  93. 93. Strings - double quotes You can use double quotes to enclose single quotes $outputstring=”He then said ‘Goodbye’ and left”;
  94. 94. Operators Standard arithmetic operators: +, -, *, /, % .. Concatenation operator: . $outputstring=”He then said “.$quote; Any non-string value is converted to a string before the concatenation.
  95. 95. Operators $aBool=true; $anInt=156; $aFloat=12.56; $anotherFloat=12.2E6; $massiveFloat=12.2E-78; print "The bool printed looks like this: ".$aBool."<br />"; print "The int printed looks like this: ".$anInt."<br />"; print "The (smaller) float printed looks like this: ".$aFloat."<br />"; print "The larger float printed looks like this: ".$anotherFloat."<br />"; print "The even larger float printed looks like this: ".$massiveFloat."<br />";
  96. 96. Operators $aBool=true; $anInt=156; $aFloat=12.56; $anotherFloat=12.2E6; $massiveFloat=12.2E-78; print "The bool printed looks like this: ".$aBool."<br />"; print "The int printed looks like this: ".$anInt."<br />"; print "The (smaller) float printed looks like this: ".$aFloat."<br />"; print "The larger float printed looks like this: ".$anotherFloat."<br />"; print "The even larger float printed looks like this: ".$massiveFloat."<br />";

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