PHP: Difference between revisions

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**Remember,  a standard header (and footer) can make all your web pages look similar and there is only one place where you need to edit to change that look. But equally using a script a web page can look different depending on any data you choose (time of day, current season, whether it is raining, how hot it is) or it can display different content depending on particular values.  
**Remember,  a standard header (and footer) can make all your web pages look similar and there is only one place where you need to edit to change that look. But equally using a script a web page can look different depending on any data you choose (time of day, current season, whether it is raining, how hot it is) or it can display different content depending on particular values.  
*Some other scripts might contain standard functions (like connecting to a database, reading from a database,  calculating highest or lowest, or they might contain some of your intellectual property in terms of a script that you want to place in a secure location only known when parsing within the web server, so cannot be accessed from the browser and so cannot be hacked.
*Some other scripts might contain standard functions (like connecting to a database, reading from a database,  calculating highest or lowest, or they might contain some of your intellectual property in terms of a script that you want to place in a secure location only known when parsing within the web server, so cannot be accessed from the browser and so cannot be hacked.
A common mistake with includes is to forget to specify the path correctly. If all files are in same directory use '''.\file_name.extension''' syntax, this is called relative paths and means the requested file is in same directory as calling file. Leaving out the prefix, and the PHP parser will load the first file it finds with that name following the defined'''include_path''' rules. A standard one might start with "./" as first path, but you cannot assume that is the first path if you are writing a script others might use. Equally if all the files to be included are in a common directory at same level as the directory where the calling files are use '''../common/file_name.extension''' syntax.  If you are writing a script that might be used with different web pages, or even in batch, so you cannot be sure of the relative path between calling script and file to be included, declare the absolute path, if necessary using whatever constant represents the root (it might be $_SERVER[DOCUMENT_ROOT]) in the path.


=== Learning More about PHP ===
=== Learning More about PHP ===
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