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Chapter 10 Using Include Statements - Page 281-284

• 281 Using Include Statements
  • 281 Put all or most of your HTML into include files
  • 281 Store the information needed to access the database in a file separate from your program
  • 282 Put your functions in include files
  • 282 Store statements that all the files on your Web site have in common
• 284 Using functions
  • 284 Make frequent use of functions
  • 284 Look for opportunities to use functions
  • 284 Give descriptive names to your functions

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• 281Using Include Statements
  • 281 Using Include Statements
    • PHP allows you to put statements into an external file
      • that is a separate file where the rest of the program or HTML page is stored
    • you can insert this external file whenever or where ever you need it
      • by using the include statement
    • include statements are useful for storing a block of statements that are repeated
      • you add the include statement where ever you want the blocks of code instead of the actual block of code
    • this makes your main program shorter and easier to read
    • the format for the include statement is as follows
      • include("filename")
      • the file can have any name
      • some folks use the .inc file extention
    • statements in an include file are considered HTML code, not PHP code
      • if you want to include PHP code you will need the php tags <?php ... ?>
        • to surround your PHP code.
  • 281 Put all or most of your HTML into include files
    • If you use forms in your pages, place the code for the forms in an include sttm so you can use that code in multiple places.
  • 281 Store the information needed to access the database in a file separate from your program
    • store the vaiable names in the file as follows
      • <?php
        $host="localhost";
        $user="phpuser";
        $password="secret";
        ?>
    • advantages to doing this is there is now one file to update if you have to change the hostname, username, or password
    • include this file near the top of the program that needs to connect to a database
    • do not call the include file password.inc, that makes it easier for a hacker to find
      • use a misleading filename to make it harder for hackers to find
  • 282 Put your functions in include files
    • it is suggested that you place functions in a separate include file
    • if you have a lot of functions,
      • organize related functions into several include files such as data_functions.inc and form_functions.inc
    • use include statements near the top of your programs, reading in the functions that are used for that program.
  • 282 Store statements that all the files on your Web site have in common
    • If all your pages have the same header, sidebar navigation, (the same look and feel)
      • place all that HTML code into an external file that you can include.
    • If all your pages include the same file, and you need to make a change to that look and feel
      • you only have to make that change once to effect the entire web site
    • PHP provides a related statement the include_once statement
      • if the specified file has already been included in a previous statement, the file is not included again
      • the format is as follows
        • include_once ("$filename");
      • This sttm prevents include files with similar variables from overwriting each other.
        • Use include_once when you include your functions.
    • You can use a variable name for the filename as follows
      • include ("$filename");
      • pages 282-283 has an example where there are 7 different files for the days of the week
    • you can use the following sttms to display the correct message for the current day
    • <?php
      $today = date("D");
      include("$today"."inc");
      ?>
    • After the first statement, $today contains the day of the week, in abbreviation form.
    • The second statement includes the correct file, using the day stored in $today.
    • If $today contains Sun, the statement includes a file called Sun.inc
• 283 Protecting your include files is important
  • The best way to protect them is to store them in a directory outside your Web space so they cannot be accessed by visitors to your Web site.
  • You can set up an include directory where PHP looks for any files specified in an include statement.
  • If you are the Administrator, you can set up an include directory in the php.ini file.
    • Find the setting for include_path and change it to the path to your preferred directory.
    • If a semicolon appears at the beginning of the line, before include_path, remove it.
    • The following are examples of the include_path settings in the php.ini file:
    • include_path = ".;d:\include";         # for Windows
    • include_path = ".:/user/include";      # for Unix/Linux/Mac
    • Both sttms specify two directories where PHP looks for include files.
      • the first directory is .(dot) meaning the current directory, followed by the second directory path
    • You can specify as many include directories as you want, PHP will search them all for your include file.
      • The directory paths are separated by semicolons for Windows and a colon for Unix
  • If you do not have access to the php.ini file, you can set the path in the individual script by using the following statement
    • ini_set ("include_path", "d:\hidden");
    • This sttm sets the include_path to the specified directory only while the program is running
    • It does not set the directory for the entire Web site
  • To access a file from an include directory, just use the filename, you do not need the full path name
    • example: include("secreatpasswords.inc");
  • 284 if your include file is not in an include directory, you may need to use the entire path name in the include sttm.
    • if the file is in the same directory as your program, the file name alone is ok
    • if the file is not in the same directory, use the include sttm as follows:
      • include("d:/hidden/secreatpasswords.inc");
• 284 Using functions
  • 284 Make frequent use of functions
  • 284 Look for opportunities to use functions
    • Functions from older projects can be used in newer projects
  • 284 Give descriptive names to your functions

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