Require vs Include
Require and include are two commonly used terms in PHP programming. Do these two have any differences between them? This article evaluates the differences between these two common terms. The basic definition of require indicates that a specific file is not mandatory and can be included as many times as possible wherever it is required. Include produces a warning that ensures the continued execution in the event the file does not exist. Require, on the other hand, is a file that must be included depending on the number of times it is used. In the event that a given file does not exist, it produces an error and stops overall execution.
At face value, both require and include seem the same as they both handle failures in a similar manner. A difference is however noted with require that handling of fatal errors is different from how they are handled in include. Require results in a fatal error and does not allow for the processing of the page. Include, on the other hand, allows for the script to continue reading, even after a fatal error has occurred. Include will only notify you of an error having occurred but the other script continues to read. In the event that halting of a page is needed in the event of a fatal error occurring, require is the only solution. It is also recommended that the include path settings factored in during programming are well placed.
Another difference between the two is that include allows for the inclusion of the specified file. When include is specified as the command once, the file in question will only execute once, irrespective of the number of times that the file has appeared previously in the script. Require only reads in the target file, even in the case where it is placed in a line that will never execute. To conditionally include a specific file, the use of include is recommended. This does not in any way affect require. In a case where the line in which require is not executed, nothing else in the specified target file is executed.
The choice of whether to use require or include should be specially based on the specific situation. Use of require should be done for pages that are of high essentiality to the rest of the page. In the case of a page that needs a person to enter login details, require is the better choice over include. Require will produce a fatal error when the wrong combination is entered, as opposed to include which can at times allow for a function to be overlooked.
In creating applications that are complex and would not desire to make fatal errors, use of include can be preferred. This means that in the event an error occurs, execution of other files can continue. End users, on the other hand, can help pinpoint the location of the error, rather than when using require, everything stops as scanning is done by the PHP parser before execution occurs. Include will execute while at the same time the PHP parser scans it.
Summary
Require and include are common terms used in PHP programming
Include produces a warning but execution continues
Require halts everything in a specific file when an error occurs
Require produces a fatal error in the event of an execution problem
Include only gives a warning and continues to execute
Include, when specified once as a command, only executes once
In conditional inclusion of a specific file needs, the use of include is preferred
Ultimate choice of whether to use require or include should be based on situation, though include offers more freedom