A340 Laboratory Session #12

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1 A340 Laboratory Session #12 LAB GOALS Understanding Arrays and Files in PHP Basic output and debugging techniques (echo, print, print_r, var_dump()) Step 1: Start with a simple HTML file similar to figure below. Note three issues: First, note that the BODY of the of the HTML file has a <?PHP.?> section in it. Second, remember to save this file with a (.php) extension, otherwise the web server will not know that it has to be sent to the PHP pre-processor. Third, make sure that your WAMP, XAMPP, etc is running! <!DOCTYPE html> <html> <head> </head> <body> <?php </body> </html>?> Step 2: Start by creating an associative array and putting some data in it. Note DO NOT simply copy and paste the code provided below in to your lab. Type it yourself, so that you become familiar with the syntactic and semantic errors that occur when your code and make mistakes. Understanding and fixing these errors will save you quite a bit of time later when you work on your assignment. Also you are more like to remember it for the test or quiz. $mystudents = array(); $mystudents[0] = array("name" => "Tom", "Grade" => 79); $mystudents[1] = array("name" => "Sue", "Grade" => 82); $mystudents[2] = array("name" => "Jack","Grade" => 69); $mystudents[3] = array("name" => "Niki","Grade" => 92); Step 3: Now write a for loop to display the content of this associative array: echo("<h3>display Array content using for loop</h3>"); for($i = 0; $i < sizeof($mystudents); $i++) echo("mystudents[$i][name] = ". $mystudents[$i]["name"]. "<br />"); echo("mystudents[$i][grade] = ". $mystudents[$i]["grade"]. "<br />"); Step 4: Now print the same array using the print_r() function. Also notice the use of the <pre> HTML tag. echo("<h3>display Arrays content using print_r()</h3>"); echo("<pre>"); print_r($mystudents); // Print readable echo("</pre>"); echo("<hr>"); Step 5: Now print the array using the var_dump() function: echo("<h3>display Array content using var_dump()</h3>"); var_dump($mystudents); // dump the type and value of the variable At this point you should understand how associative arrays work, and how you can put data into and extract data out of the array. The output of your lab should look something like the following figure. 1

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Step 6: Now we would like to store the content of the array into a sequential file: (Review the lecture on File I/O) echo("<h3> Storing the array content into a sequential file: (lab12.

3 Step 6: Now we would like to store the content of the array into a sequential file: (Review the lecture on File I/O) echo("<h3> Storing the array content into a sequential file: (lab12.txt) </h3>"); $filename = "lab12.txt"; $fp = fopen($filename, "w"); // "w" = write to the file for($i = 0; $i < sizeof($mystudents); $i++) fwrite($fp, $mystudents[$i]["name"]. "\n"); fwrite($fp, $mystudents[$i]["grade"]. "\n"); fclose($fp); 3

Step 7: Let s try a slight variation. Let s try to create what I would call a Semi-XML format for the file. The advantage of an XML file is that it is self describing.

4 Step 7: Let s try a slight variation. Let s try to create what I would call a Semi-XML format for the file. The advantage of an XML file is that it is self describing. In other words, you place some tags in the file which allows the reader (human or machine) to be able to recognize and understand the format and content of your data file. (you can read more about XML here: or here: ) echo("<h3> Storing the array content into a Semi-XML sequential file: (lab12_xml.txt) </h3>"); $filename = "lab12_xml.txt"; $fp = fopen($filename, "w"); // "w" = write to the file for($i = 0; $i < sizeof($mystudents); $i++) fwrite($fp,"<name>". "\n"); fwrite($fp, $mystudents[$i]["name"]. "\n"); fwrite($fp,"</name>". "\n"); fwrite($fp,"<grade>". "\n"); fwrite($fp, $mystudents[$i]["grade"]. "\n"); fwrite($fp,"</grade>". "\n"); fclose($fp); 4

Step 8: Let s try to now open the file, read its content and display it on screen. Review the lecture on FILE I/O. Try to do this on your own. If you are having difficulty, go to page 7 of this lab.

5 Step 8: Let s try to now open the file, read its content and display it on screen. Review the lecture on FILE I/O. Try to do this on your own. If you are having difficulty, go to page 7 of this lab. Step 9: Now try to read the Semi-XML file and display its content: Try to do this on your own. If you are having difficulty, go to page 7 of this lab. The result of steps 8 and 9 should look something like the figure below: 5

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7 Solution to Steps 8 and 9 (ONLY look at this code if you can t figure out how to complete step 8 and 9 on page 5) Step 8: Let s try to now open the file, read its content and display it on screen. Review the lecture on FILE I/O. echo("<h3> Reading and displaying the file content: (lab12.txt) </h3>"); $filename = "Lab12.txt"; // open for read and get a file pointer $fp = fopen($filename, "r"); if( $fp == false) // Problem opening the file echo("error opening: ". $filename); exit(); // Read the file one line at a time while(!feof($fp)) $aline = trim(fgets($fp)); echo($aline); echo("<br />"); Step 9: Now try to read the Semi-XML file and display its content: echo("<h3> Reading and displaying the file content: (lab12_xml.txt) </h3>"); $filename = "Lab12_XML.txt"; // open for read and get a file pointer $fp = fopen($filename, "r"); if( $fp == false) // Problem opening the file echo("error opening: ". $filename); exit(); // Read the file one line at a time while(!feof($fp)) $aline = trim(fgets($fp)); // note the use of the trim() function switch ($aline) case "<name>" : $name = trim(fgets($fp)); // get the next line (student name) echo("name: ". $name. "<br />"); $throwaway = fgets($fp); // throw away </name> break; case "<grade>" : $grade = (int) trim(fgets($fp)); // cast the grade into an integer echo("grade: ". $grade. "<br />"); $throwaway = fgets($fp); // throwaway </grade> break; default : echo("blank line or Unrecognized token in file: ". $filename); break; 7

Course Topics. The Three-Tier Architecture. Example 1: Airline reservations. IT360: Applied Database Systems. Introduction to PHP

Course Topics. The Three-Tier Architecture. Example 1: Airline reservations. IT360: Applied Database Systems. Introduction to PHP Course Topics IT360: Applied Database Systems Introduction to PHP Database design Relational model SQL Normalization PHP MySQL Database administration Transaction Processing Data Storage and Indexing The