tailieunhanh - PHP and MySQL Web Development - P19

PHP and MySQL Web Development - P19: PHP and MySQL Web Development teaches the reader to develop dynamic, secure, commercial Web sites. Using the same accessible, popular teaching style of the first edition, this best-selling book has been updated to reflect the rapidly changing landscape of MySQL and PHP. | Opening a File 57 Figure PHP will specifically warn you when a file can t be opened. If you get this error you need to make sure that the user that the script runs as has permission to access the file you are trying to use. Depending on how your server is set up the script might be running as the Web server user or as the owner of the directory that the script is in. On most systems the script will run as the Web server user. If your script was on a UNIX system in the - public_html chapter2 directory you would create a world writeable directory in which to store the order by typing the following mkdir - orders chmod 777 - orders Bear in mind that directories and files that anybody can write to are should not have directories that are accessible directly from the Web as writeable. For this reason our orders directory is two subdirectories back above the public_html directory. We will talk more about security later in Chapter 13 E-commerce Security Issues. Incorrect permission settings is probably the most common thing that can go wrong when opening a file but it s not the only thing. If the file can t be opened you really need to know this so that you don t try to read data from or write data to it. If the call to fopen fails the function will return can deal with the error in a more user-friendly way by suppressing PHP s error message and giving your own 58 Chapter 2 Storing and Retrieving Data @ fp fopen DOCUMENT_ROOT . orders a 1 if fp echo p strong Your order could not be processed at this time. . Please try again later. strong p body html exit The @ symbol in front of the call to fopen tells PHP to suppress any errors resulting from the function call. Usually it s a good idea to know when things go wrong but in this case we re going to deal with that elsewhere. This line can also be written as follows fp fopen DOCUMENT_ROOT . orders a 1 but this does tend to make it less obvious that you are using the error .