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USING PHP TO MANAGE FILES pass the URL as an argument to the function. Unfortunately, as noted earlier, many hosting companies disable the allow_url_fopen setting in PHP. One way to get around this is to use a socket connection instead. To create a socket connection, use the fsockopen() function, which takes the following five arguments: The target domain name The port you want to open for web pages, this is always 80 A variable to capture an error number if the connection fails A variable to capture any error message The number of seconds to attempt the connection before timing out Only the first argument is required, but using all five is a good idea since you can always use the same values, and the error message may help you understand what s gone wrong if the connection fails. The fsockopen() function works in a very similar way to fopen() by opening a file for you to read. Let s use fsockopen() to access the friends of ED news feed at www.friendsofed.com/ news.php. PHP Solution 7-5: Opening a news feed with fsockopen() 1. Create a PHP file called fsockopen.php in the filesystem folder. If you just want to study the final code, use fsockopen.php in the download files for this chapter. 2. If your script editor automatically inserts a DOCTYPE declaration and XHTML skeleton, remove them. You need to start with a blank page. Insert the following code: This is the basic skeleton for any socket connection using fsockopen(). The only change you normally need to make is to the first argument, which is the domain name of the site that you want to access. If a connection can t be made, the first half of the conditional statement displays the error message and number. If the error number is 0, it may indicate the socket connections have been disabled on your server. In that event, consult your hosting company. If a successful connection is made, the else clause is executed. At the moment, it contains just a comment. So let s fix that now. 203
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PHP SOLUTIONS: DYNAMIC WEB DESIGN MADE EASY number and then builds the filename from its composite parts. A series can contain up to 999 files and still remain in the correct order. The full listing follows: function getNextFilename($dir, $prefix, $type) { // run some security checks on the arguments supplied if (!is_dir($dir)) return false; if (!preg_match(’/^[-._a-z0-9]+$/i’, $prefix)) return false; $permittedTypes = array(’txt’,'doc’,'pdf’,'jpg’,'jpeg’,'gif’,'png’); if (!in_array(strtolower($type), $permittedTypes)) return false; // if the checks are OK, get an array of the directory contents $existing = scandir($dir); // create a search pattern for files that match the prefix and type $pattern = ‘/^’.$prefix.’(d+).’.$type.’$/i’; $nums = array(); // loop through the directory // get the numbers from all files that match the pattern foreach ($existing as $file) { if (preg_match($pattern, $file, $m)) { $nums[] = intval($m[1]); } } // find the highest number and increase it by 1 // if no file yet created, assign it number 1 $next = $nums ? max($nums)+1 : 1; // calculate how many zeros to prefix the number with if ($next < 10) { $zeros = '00'; } elseif ($next < 100) { $zeros = '0'; } else { $zeros = '' ; } // return the next filename in the series return "{$prefix}{$zeros}{$next}.{$type}"; } As with the buildFileList() function, I have created an array of acceptable file types (highlighted in bold on line 5 in the preceding code). Although create_series.php is used to create a text file, you can incorporate this function in a file upload script. If you need to change the range of acceptable file types, amend the $permittedTypes array. The function should not need any other alteration. The PHP 4 version is identical except for the way it opens and inspects the directory. Opening remote data sources PHP can open publicly available files on other servers just as easily as on the same server. This is particularly useful for accessing XML files or news feeds. All that you need to do is
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USING PHP TO MANAGE FILES The first two lines assign the target folder to a variable and call getNextFilename5() (use getNextFilename4() for PHP 4) to generate the next filename in the series. The function runs a number of checks on the three arguments and returns false if any fail. So the next section of code is wrapped in a conditional statement to ensure that the script attempts to create a new file only if a valid filename is obtained. The call to fopen() is enclosed in another conditional statement. This checks that the file has been successfully created before attempting to write to it. If the file can t be opened, a suitable message is assigned to $result. The final else clause belongs to the following conditional statement: if ($filename) { So, if getNextFilename() returns false, $result reports the likely reasons for failure. 5. Insert the following PHP code between the opening and

PHP SOLUTIONS: DYNAMIC WEB DESIGN MADE EASY I ve turned this into a function called getNextFilename(), which you can find in getNextFilename5.php and getNextFilename4.php in the download files for this chapter. The function takes the following three arguments: The pathname of the directory where you want the new file to be created The prefix of the filename, which must consist of alphanumeric characters only The filename extension (without a leading period) Let s say you choose comment as the prefix and txt as the filename extension. The getNextFilename() function generates a series of files called comment001.txt, comment002.txt, and so on. PHP Solution 7-4: Using the getNextFilename() function 1. Copy getNextFilename5.php (or getNextFilename4.php, if your server is running PHP 4) from the download files, and save it in the includes folder. 2. Open fopen_exclusive.php from the download files and save it in the filesystem folder as create_series.php. If you just want to read along, the finished code is in the download version of create_series.php. 3. Include the file that contains the getNextFilename() function for the appropriate version of PHP. You need the function only when the form is submitted, so place it inside the conditional statement at the top of the page like this (again, for brevity, I m not checking that the include file exists): if (array_key_exists(’putContents’, $_POST)) { include(’../includes/getNextFilename5.php’); 4. Then, after the line that removes backslashes from the form output, amend the rest of the PHP block at the top of the page like this: $dir = ‘C:/private’; $filename = getNextFilename5($dir, ‘comment’, ‘txt’); // attempt to create file only if $filename contains a real value if ($filename) { // create a file ready for writing only if it doesn’t already exist if ($file = @ fopen(”$dir/$filename”, ‘x’)) { // write the contents fwrite($file, $contents); // close the file fclose($file); $result = “$filename created”; } else { $result = ‘Cannot create file’; } } else { $result = ‘Invalid folder or filename’; } }
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USING PHP TO MANAGE FILES $fileTypes = array(’jpg’,'jpeg’,'gif’,'png’); // traverse folder, and add file to $found array if type matches $found = array(); foreach ($contents as $item) { $fileInfo = pathinfo($item); if (array_key_exists(’extension’, $fileInfo) && . in_array($fileInfo[’extension’],$fileTypes)) { $found[] = $item; } } // Check the $found array is not empty if ($found) { // sort in natural, case-insensitive order, and populate menu natcasesort($found); foreach ($found as $filename) { echo “$filenamen”; } } } } How the buildFileList() function works I suspect many readers will be happy just to use the function, but if you re curious as to how it works, here s a brief description to flesh out the inline comments. After the folder has been opened, each item is passed to a PHP function called pathinfo(), which returns an associative array with the following elements: dirname: The name of the directory (folder) basename: The filename, including extension (or just the name if it s a directory) extension: The filename extension (not returned for a directory) Because the extension element is not returned for a directory, you need to use array_key_exists() before attempting to check its value. The second half of the condi tional statement in line 12 uses in_array() to see if the value of extension matches one of the file types that you re looking for. It there s a match, the filename is added to the $found array. It s then just a case of building the elements with a foreach loop, but to add a user-friendly touch, the $found array is first passed to the natcasesort() function, which sorts the filenames in a case-insensitive order. Automatically creating the next file in a series In the last chapter I showed you how to create a unique filename by adding a timestamp or using the date() function to generate the date and time in human-readable format. It works, but is hardly ideal. A numbered series, such as file01.txt, file02.txt, and so on, is usually better. The problem is that a PHP script has no way to keep track of a series of numbers between requests to the server. However, by inspecting the contents of a direc tory, you can use pattern matching to find the highest existing number, and assign the next one in the series. 199
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PHP SOLUTIONS: DYNAMIC WEB DESIGN MADE EASY 3. Create a form inside imagelist.php, and insert a
element with just one like this:
Select an image

This is the only static element in the drop-down menu. 4. Amend the code in the previous step like this (new code is shown in bold):

Make sure that the pathnames to the include file and the images folder are correct for your site s folder structure. If you re using PHP 4, the two lines in the PHP code block need to refer to the PHP 4 version of the function like this: include(’../includes/buildFileList4.php’); buildImageList4(’../images’); For brevity, I m not using the techniques in Chapter 4 for checking that the include file exists. 5. Save imagelist.php and load it into a browser. You should see a drop-down menu listing all the images in your images folder, as shown in Figure 7-1. When incorporated into an online form, the filename of the selected image appears in the $_POST array identified by the name attribute of the
element in this case, $_POST[’pix’]. That s all there is to it! You can adapt this function to display any type of file simply by changing the filename extensions listed in the $fileTypes array (highlighted in bold on line 7 in the following listing). This listing shows the PHP 5 version; the PHP 4 version is identical except for the way it opens and inspects the directory: function buildFileList5($theFolder) { // execute code if the folder can be opened, or fail silently if ($contents = @ scandir($theFolder)) { // initialize an array for matching files $found = array(); // Create an array of file types
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How to cite a web site - USING PHP TO MANAGE FILES Building a drop-down

Sunday, January 27th, 2008

USING PHP TO MANAGE FILES Building a drop-down menu of files When you work with a database, you ll find you often need a list of images or other types of files in a particular folder. For instance, you may want to associate a photo with a blog entry or product detail page. Although you can type the name of the image into a text field, you need to make sure that the image is there and that you spell its name correctly. Get PHP to do the hard work for you by building a drop-down menu automatically. It s always up-to-date, and there s no danger of misspelling the name. I find this so convenient that I have turned the whole process into a function. There are two versions in the download files: one for use with PHP 5 and later, and the other for PHP 4. So, with just two lines of code, you can create a drop-down menu like that shown in Figure 7-1. Figure 7-1. PHP makes light work of creating a drop-down menu of images in a specific folder. PHP Solution 7-3: Using the buildFileList() function 1. Create a PHP page called imagelist.php in the filesystem folder. If you just want to study the code, use either imagelist_php5.php or imagelist_php4.php from the download files, depending on the version of PHP running on your server. 2. Copy buildFileList5.php (for PHP 5) or buildFileList4.php (for PHP 4) to your includes folder. 197
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Web design software - PHP SOLUTIONS: DYNAMIC WEB DESIGN MADE EASY As

Sunday, January 27th, 2008

PHP SOLUTIONS: DYNAMIC WEB DESIGN MADE EASY As you can see from the screenshot on the previous page, the folder doesn t contain only images, so it s necessary to extract them before you can build a drop-down menu. First let s take a look at how to do the same thing in PHP 4. Opening a directory to inspect its contents If your server is still running PHP 4, complain to your hosting company (PHP 5 has been a stable release since July 2004), and in the meantime do things the old way. Inspecting a directory is similar to opening a file for reading or writing. It involves the following three steps: 1. Open the directory with opendir(). 2. Read the directory s contents with readdir(). 3. Close the directory with closedir(). So, instead of the single line of code required in PHP 5 or later, you need this (the code is in opendir.php in the download files): // open the directory $folder = opendir(’../images’); // initialize an array to store the contents $files = array(); // loop through the directory while (false !== ($item = readdir($folder))) { $files[] = $item; } // close it closedir($folder); The readdir() function gets one item at a time and uses an internal pointer in the same way as the functions used with fopen(). To build a list of the directory s entire contents, you need to use a while loop and store each result in an array. The condition for the loop is contained in the following line: while (false !== ($item = readdir($folder))) { The readdir() function returns false when it can find no more items, so to prevent the loop from coming to a premature end if it encounters an item named 0, for example, you need to use false with the nonidentical operator (!==). Of course, it s unlikely you ll intentionally name an item 0. However, good programmers expect the unexpected. This makes absolutely sure the function works as intended. Each time the while loop runs, $item stores the name of the next file or folder, which is then added to the $files array. Using this trio of functions isn t difficult, but the one-line scandir() is much simpler.
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USING PHP TO MANAGE FILES If you study

Saturday, January 26th, 2008

USING PHP TO MANAGE FILES If you study the preceding code, you ll notice that the second read operation uses fread(). It works perfectly with this example, but contains a nasty surprise. Change the code in fopen_pointer.php to add the following line after the external file has been opened (it s commented out in the download version): $file = fopen($filename, ‘r+’); fseek($file, 0, SEEK_END); This moves the pointer to the end of the file before the first write operation. Yet, when you run the script, fread() ignores the text added at the end of the file. This is because the external file is still open, so filesize() reads its original size. Consequently, you should always use a while loop with !feof() and fgets() if your read operation takes place after any new content has been written to a file. The changes to a file with read and write operations are saved only when you call fclose() or when the script comes to an end. Although PHP saves the file if you forget to use fclose(), you should always close the file explicitly. Don t get into bad habits; one day they may cause your code to break and lose valuable data. When you create or open a file in a text editor, you can use your mouse to highlight and delete existing content, or position the insertion point exactly where you want. You don t have that luxury with a PHP script, so you need to give it precise instructions. On the other hand, you don t need to be there when the PHP script runs. Once you have designed it, it runs automatically every time. Exploring the file system PHP s file system functions can also open directories (folders) and inspect their contents. From a web designer s viewpoint, the most practical applications of this are building a drop-down menu of files and creating a unique name for a new file. Inspecting a directory the quick way If your server runs PHP 5 or later, you can use the scandir() function, which returns an array consisting of the files and directories within a specified directory. Just pass the pathname of the directory as a string to scan dir(), and store the result in a variable like this: $files = scandir(’../images’); You can examine the result by using print_r() to display the contents of the array, as shown in the screenshot to the right (the code is in scandir.php in the download files).
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PHP SOLUTIONS: DYNAMIC WEB DESIGN MADE EASY (Free php web host) The

Friday, January 25th, 2008

PHP SOLUTIONS: DYNAMIC WEB DESIGN MADE EASY The download file also contains code that displays the values of $readRest, $readAll, and $readAgain to show what happens at each stage of the read/write operations. The existing content in filetest05.txt was This works only the first time. When I typed Hello in fopen_pointer.php and clicked Write to file, I got the results shown to the left. Opening filetest05.txt revealed the results to the right. Compare the screenshots to see what happened. Table 7-3 describes the sequence of events. Table 7-3. Sequence of read/write operations in fopen_pointer.php Command Position of pointer Result $file = fopen($filename, ‘r+’); Beginning of file File opened for processing fwrite($file, $contents); End of write operation Form contents overwrites beginning of existing content while (!feof($file)) { $readRest .= fgets($file); } End of file Remainder of existing content read rewind($file); Beginning of file Pointer moved back to beginning of file $readAll = fread($file, filesize($filename)); See text Content read from beginning of file fwrite($file, $contents); At end of previous operation Form contents added at current position of pointer while (!feof($file)) { $readAgain .= fgets($file); } End of file Nothing read because pointer was already at end of file fclose($file); Not applicable File closed and all changes saved
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