IEEM 230. PHP Basics, Part IV. Objectives of the lab:

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1 IEEM 230. PHP Basics, Part IV Objectives of the lab: Learn the fundamentals of PHP - different types of data inputs using web FORMS - I/O from files - more PHP practice Standard PHP reference website: PHP quick reference: Templates for Simple FORM and php CGI: Startup Form, Startup CGI program Reference: Example 1. HTML Forms Up to now, we mostly used simple <input..> filed to get user inputs from forms. The following example will demonstrate almost all the different formats in which you can get user-inputs. <title> IELM 230, Comprehensive FORM template </title> <b><font color=blue> Below are the common ways provided by HTML for user-provided data using forms. </b> </font> <!-- DEBUG mode > <!-- (i) remove '!--' in the next line (ii) replace USER-LOGIN (iii) replace CGI-FILENAME > <!-- form method=post action=" FILE.php" > <!-- Normal mode. (a) Comment out the DEBUG mode above (ii) Replace USER-LOGIN (iii) replace CGI-FILENAME > <form method=post action=" <b>1. One line text input:</b> <input name=f_line type=text size=25> <b>2. Multi-line text input (textbox):</b> <textarea name=f_nlines rows=10 cols=80> </textarea> <b>3. To select one option from a list:</b> <select name=f_select>

2 <option value=hk> Hong Kong <option value=kln selected> Kowloon <option value=nt> NT </select> <b>4. Radio-button (to select one item from a list):</b> <input type=radio name=f_radio value=1 checked> Wong Kar Wai <input type=radio name=f_radio value=2 > Eric Rohmer <input type=radio name=f_radio value="steven Speilberg" > Steven Spielberg <b>5. To select one or more items from a list (use CTRL-click):</b> <select multiple name="f_scroll[]" size=1> <option value="bruce Lee"> Bruce Lee <option value="jacky Chan"> Jacky Chan <option value="jet Li"> Jet Li </select> <b>6. To select zero or more options from a list:</b> <input type=checkbox name="f_check[]" value="cha Siu Bao"> Cha Siu Bao <input type=checkbox name="f_check[]" value="siu Maai"> Siu Maai <input type=checkbox name="f_check[]" value="ha Gau"> Ha Gau <b>7. Hidden input field (not displayed; use View->Source to see it! <input type=hidden name=f_hidden value="you cannot see me"> <b>8. Undisplayed text input (for typing passwords; not secure!): <input type=password name=f_password size=15> <b>9. Each form nust have a submit-button:</b> <input type=submit value="click Here to submit data"> <b>10. A reset button can clear all input values:</b> <input type=reset value="reset All Choices"> </form> Below is the PHP code that will (a) get all the variables and their values submitted by the above FORM. In this program, the only action we take is to print the information back to the client. However, in real applications, you will need to write programs to do some more useful stuff.

3 #!/usr/local/bin/php -- <title> IELM 230, Comprehensive FORM CGI program </title> <?php // First get the input variables and their values $cgi_line = $_POST['f_line']; $cgi_nlines = $_POST['f_nlines']; $cgi_select = $_POST['f_select']; $cgi_radio = $_POST['f_radio']; for ($i = 0; $i < count($_post['f_scroll']); $i++) { $cgi_scroll[$i] = $_POST['f_scroll'][$i];} for ($i = 0; $i < count($_post['f_check']); $i++) { $cgi_check[$i] = $_POST['f_check'][$i];} $cgi_hidden = $_POST['f_hidden']; $cgi_password = $_POST['f_password']; // Do something with the inputs submitted by the user (here, print them back to the client). echo "The inputs you submitted were: <br>\n"; echo "1. f_line: $cgi_line "; echo "2. f_nlines: <pre> $cgi_nlines </pre>"; echo "3. f_select: $cgi_select "; echo "4. f_radio: $cgi_radio "; echo "5. f_scroll: "; for ($i = 0; $i < count($cgi_scroll); $i++) { echo "$cgi_scroll[$i] ";} echo ""; echo "6. f_check: "; for ($i = 0; $i < count($cgi_check); $i++) { echo "$cgi_check[$i] ";} echo ""; echo "7. f_hidden: $cgi_hidden "; echo "8. f_password: $cgi_password "; echo "";?>

4 This is a fairly long example, but you should look carefully at the syntax for each type of input. In particular, one point is very important to note: Some inputs have the possibility of getting more than one values (e.g. Checkboxes, or <select multiple > type of inputs. For such inputs, if you use an ordinary variable, then PHP can only set its value to one of the selections. For example, in our multiple select input, you can use CTRL-click to select two choices, say, Jacky Chan and Jet Li. In this case, using an ordinary variable as input only gives one value (either Jacky Chan, or Jet Li), which is not the same as the user intent. In PHP, this problem is solved by setting this type of input as an array. Iin our example: <select multiple name="f_scroll[]" size=1>, the name, f_scroll, is followed by the array identifier, [ ]. The same is true for the checkbox example. Example 2..File I/O In this example, we learn how to do I/O from a file. There are three main modes to open a file: r read data from a file; w write data into a file (overwrite previous contents); a write data at the end of a pre-existing file, i.e. append data to the file. In the example below, we will use an architecture that is quite common in many web applications: (1) User submits a request for some action (2) The CGI program receives request, and collects some data (e.g. from a file, or a DB) (3) The CGI returns a new form to the user based on collected data (4) User submits what action should take place (5) The second CGI program performs the action, and returns result to user (client). ~~~~~~ Filename: games ~~~~~~ Nintendo Chess Go Bridge Mahjongg ~~~~~~ End of file ~~~~~ IMPORTANT: the above file must be located in the same folder as the CGI script file that will access it (or in a directory that is accessible to the CGI program). ~~~~~~~~The FORM that allows you to run the script that will do the I/O~~~~~ <title> IELM 230, File I/O example, first form </title>

5 <!-- Normal mode. (a) Comment out the DEBUG mode above (ii) Replace USER-LOGIN (iii) replace CGI-FILENAME > <form method=post action=" <b>click button to see the choice of games:</b> <input type=submit value="click me"> </form> ~~~~~~~~~The CGI program that will react to this form (file: lab5_ex2a.php)~~~~~ #!/usr/local/bin/php -- <title> IELM 230, File I/O Example </title> <form method=post action=" <b>please select your favourite game:</b> <select name=f_select> <?php $link= fopen( "data", "r"); while (!feof( $link)) { $game = fgets( $link, 30); echo "<option value=$game> $game"; }?> </select> <b>submit my choice:</b> <input type=submit value="click Here to submit your choice"> </form>

6 NOTES: 1. Notice that this CGI program returns an HTML document to the web-client, which also contains another FORM! 2. The File I/O function used is called fopen, and, if it is successful, it returns the name of a stream, or link, from which PHP can read data. 3. Function fgets reads one line at a time. It has two arguments; the first is the stream to read; the second is the maximum expected length of the line [e.g. fgets( $link, 30) will read maximum 30 characters.] 4. When this FORM is submitted, another CGI program is called (file: lab5_ex2b.php). ~~~~~~~~The CGI program that will react to the FORM created by the first CGI~~~~~~~~ #!/usr/local/bin/php -- <title> IELM 230, File I/O Example </title> <?php // get the data sent by the form.. $cgi_select = $_POST['f_select']; echo "You selected the game <font color=red> $cgi_select </font> <br>\n";?> Please understand the above example well: it is the basic idea behind all application programs you will write for this course. Exercises: 1. In this exercise, you will learn how to make a program to do data-entry in Databases. (i) Create a text file (filename: project_locations), with the following data: Bellaire Sugarland Houston Staffrod (ii) Create another text file (filename: dept_info), with the following data:

7 1 HQ 4 Admin 5 Research [Note: there can be one or more space, or TAB, between the Dept number and the Dept name]. (iii) Create a web-form to enter data about projects operated by a company. For each Project, we need to get the following information: Project Name ProjectNo ProjectLocation ControllingDept ProjectName: is a text field that is typed by the user Project Number: is an integer that is typed by the user Project Location: is a text field; it is selected from a drop-down selection list. The entries of the selection list are in the file called project_locations. ControllingDept: is an integer field, which is selected by the user from a Radio-button options. The text following the Radio-Button option is the Name of the Department, while the Department Number is the submitted value. The Name and number are obtained from the file dept_numbers. (iv) After the user enters the data, your PHP program must display the following information to the user: You have entered the following projects: [ One line per project.] Please enter the data for the next project: [ Form for the projects data entry ]