PHP Cookbook

18.5. Reading a File into a String

Problem

You want to load the entire contents of a file into a variable. For example, you want to determine if the text in a file matches a regular expression.

Solution

Use filesize( ) to get the size of the file, and then tell fread( ) to read that many bytes:

$fh = fopen('people.txt','r') or die($php_errormsg);
$people = fread($fh,filesize('people.txt'));
if (preg_match('/Names:.*(David|Susannah)/i',$people)) {
    print "people.txt matches.";
}
fclose($fh) or die($php_errormsg);

Discussion

To read a binary file (e.g., an image) on Windows, a b must be appended to the file mode:

$fh = fopen('people.jpg','rb') or die($php_errormsg);
$people = fread($fh,filesize('people.jpg'));
fclose($fh);

There are easier ways to print the entire contents of a file than by reading it into a string and then printing the string. PHP provides two functions for this. The first is fpassthru($fh) , which prints everything left on the file handle $fh and then closes it. The second, readfile($filename) , prints the entire contents of $filename.

You can use readfile( ) to implement a wrapper around images that shouldn’t always be displayed. This program makes sure a requested image is less than a week old:

$image_directory = '/usr/local/images'; if (preg_match('/^[a-zA-Z0-9]+\.(gif|jpeg)$/',$image,$matches) && is_readable($image_directory."/$image") && (filemtime($image_directory."/$image") >= (time() - 86400 * 7))) { header('Content-Type: image/'.$matches[1]); header('Content-Length: ...