Basic PHP. Lecture 19. Robb T. Koether. Hampden-Sydney College. Mon, Feb 26, 2108

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1 Basic PHP Lecture 19 Robb T. Koether Hampden-Sydney College Mon, Feb 26, 2108 Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

2 1 PHP 2 The echo Statement 3 Variables 4 Operators 5 Decision Structures Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

3 Outline 1 PHP 2 The echo Statement 3 Variables 4 Operators 5 Decision Structures Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

4 PHP PHP = PHP Hypertext Preprocessor. Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

5 PHP PHP = PHP Hypertext Preprocessor. So, what does the first P stand for? Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

6 PHP PHP = PHP Hypertext Preprocessor. So, what does the first P stand for? PHP code is placed in a PHP file or it can be embedded in an HTML file. When the client requests a file containing PHP code, the server Executes the PHP code. Sends the output of the PHP code to the client. Typically, the output of the PHP program is HTML code and Javascript code. Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

7 PHP Data base PHP code Browser page.html Server Client Client has browser; server has PHP code and database Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

8 PHP Data base PHP code Request HTML Browser page.html Server Client Client requests HTML file Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

9 PHP Data base Query PHP code Request HTML Browser page.html Server Client PHP code sends query to database Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

10 PHP Data base Query Results PHP code Request HTML Browser page.html Server Client Database returns results Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

11 PHP Data base Query Results HTML code Request HTML Browser page.html Server Client PHP code outputs HTML code Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

12 PHP Data base Query Results HTML code Request HTML HTML Code Browser HTML code page.html Server Client HTML code sent to client Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

13 PHP PHP Code <?php PHP_code?> PHP code is opened by <?php and is closed by?>. Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

14 Outline 1 PHP 2 The echo Statement 3 Variables 4 Operators 5 Decision Structures Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

15 The echo Statement The echo Statement echo expression; The echo statement will output the value of an expression. Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

16 The echo Statement The echo Statement <?php echo "Hello, world!";?> For example, the above code will output Hello, world! Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

17 Strings Strings and Quotation Marks <?php echo "Hello, world! "; echo Hello, "world!" ;?> Strings may be delimited by either single quotes ( ) or double quotes ("). Single quotes may be embedded within double quotes, and vice versa. The above code will output Hello, world! and Hello, "world!" Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

18 The echo Statement Concatenation echo "Hello,". " world!"; The dot (.) is the string concatenation operator. The above code will output Hello, world! Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

19 Mixing PHP and HTML Mixing PHP and HTML <html> <head> <?php echo "<title>my Web Page</title>";?> </head> <body><?php echo "<h1>my Web Page</h1></body></html>"?> Mixing PHP and HTML can be ugly, but it works. Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

20 The Extended echo Statement The Extended echo Statement echo <<<HTML long section of text HTML; Sometimes we want to echo very long string. We may use whatever delimiter we like. I suggest HTML because this form is used typically to output HTML code. Terminating delimiter must begin in column 1 and there must be nothing else on that line. This is better than writing many echo statements. Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

21 The Extended echo Statement The Extended echo Statement echo <<<HTML <html> <head> <title>my Web page</title> <style> h1 {text-align: center; color: olive;} </style> <head> <body> HTML; Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

22 Outline 1 PHP 2 The echo Statement 3 Variables 4 Operators 5 Decision Structures Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

23 Variables Assignment Statements and Data Types $x = "Hello"; // String type $x = ; // Integer type $x = $x. " bottles of beer on the wall"; // What type? echo $x; Variable names being with $. A variable s type can change. A variable s current type is determined by its current value. When the value changes, the type may change. Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

24 Variables Variables Within Strings $x = ; echo "$x bottles of beer on the wall"; echo $x bottles of beer on the wall ; What will the above code produce? Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

25 Outline 1 PHP 2 The echo Statement 3 Variables 4 Operators 5 Decision Structures Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

26 Operators PHP operators The assignment operator: = Numerical operators: +, -, *, /, %, ++, -- String operators:. Comparison operators: ==,!=, <, >, <=, >=, ===,!== The expression $a === $b is true if $a and $b have the same value and are of the same type. The expression $a!== $b is true if $a and $b have different values or are of different types. Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

27 Debugging Programs Inspecting Variables echo The value of $x is. $x. <br/> ; The most common method of debugging a PHP program is to inspect the values of variables. Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

28 Example Example $fname = Alice ; $lname = Smith ; $ssn = ; $bdate = ; $salary = ; Use PHP to create a table, with headings, that fills row 1 with the above data. Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

29 Example Example echo <<<HTML <table border="1"> <tr> <th>name</th><th>ssn</th><th>birthday</th> <th>salary</th> </tr> <tr> <td>$fname $lname</td><td>$ssn</td><td>$bdate</td> <td>$salary</td> </tr> </table> HTML; Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

30 Outline 1 PHP 2 The echo Statement 3 Variables 4 Operators 5 Decision Structures Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

31 if Statements The if Statement if (condition) true-block; else false-block; if statements in PHP are just like if statements in C. The else part is optional. If the block contains more than one statement, then group them using curly braces. Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

32 if Statements Example $online = value from database; In the last example, suppose that we have another variable $online which is 1 if the person is online and 0 if the person is not online. Add one more column to the table named Online. Fill in Yes or No, depending on whether the person is online. Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

33 Example Example echo <<<HTML <table border="1"> <tr> <th>name</th><th>ssn</th><th>birthday</th> <th>salary</th><th>online</th> </tr> <tr> <td>$fname $lname</td><td>$ssn</td><td>$bdate</td> <td>$salary</td> HTML; if ($online == 1) echo "<td>yes</td>"; else echo "<td>no</td>"; echo "</tr></table>"; Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

34 switch Statements The switch Statement switch (expression) { case value: case-block; break; }. default: default-block; break; switch statements in PHP are just like switch statements in C. Robb T. Koether (Hampden-Sydney College) Basic PHP Mon, Feb 26, / 27

Basic PHP Lecture 17

Basic PHP Lecture 17 Robb T. Koether Hampden-Sydney College Fri, Feb 24, 2012 Robb T. Koether (Hampden-Sydney College) Basic PHPLecture 17 Fri, Feb 24, 2012 1 / 30 1 PHP 2 Basic PHP 3 The Extended echo