PHP include and require usage introduction _php tutorial

There are two ways to refer to a file: Require and include. Two ways to provide different use elasticity.

Require use methods such as require ("myrequirefile.php");. This function is usually placed at the front of the PHP program, and before the PHP program executes, it is read into the file specified by require to make it a part of the PHP program's Web page. Commonly used functions, you can also use this method to introduce it into the Web page.

The features of include () and require () are basically the same (included), but there are some differences in usage, including that include () is a conditional include function, and require () is an unconditional include function. For example, in the following code, if the variable $ A is true, it will contain the file a.php:

The code is as follows	Copy Code
if ($a) { Include ("a.php"); }

Include usage methods such as include ("myincludefile.php");. This function is usually placed in the processing part of the process control. The PHP Program page reads the include file before it is read in. This way, you can simplify the process when the program executes.

and require () is different from include (), no matter what the value of $ A, the following code will include the file a.php into the file:

The code is as follows	Copy Code
if ($a) { Require ("a.php"); }

In the case of error handling, the include statement is used, and if an error occurs, the program skips the include statement, although an error message is displayed but the program will continue to execute! But Requre will give you a fatal mistake.

Error

Use the example to speak, write two php files, name test1.php and test2.php, note the same directory, do not exist a name is test999.php file.

The code is as follows	Copy Code
test.php Include ("test999.php"); echo "ABC"; ?> test2.php Require ("test999.php") echo "ABC"; ?>

Browse the first file, because we did not find the test999.php file, we see the error message, at the same time, the error message below the display of ABC, you can see a similar situation below:
Warning:include (test1aaa.php) [function.include]: failed to open stream:no such file or directory in d:websitetest.php o N Line 2

Warning:include () [function.include]: Failed opening ' test1aaa.php ' for inclusion (include_path= '.; C:php5pear ') in d:websitetest.php on line 2
Abc

Browse the second file, because we did not find the test999.php file, we see the error message, but, the error message is not shown below the ABC, you can see the situation is similar to the following:
Warning:require (test1aaa.php) [function.require]: failed to open stream:no such file or directory in d:websitetest.php o N Line 2

Fatal Error:require () [function.require]: Failed opening required ' test1aaa.php ' (include_path= '); C:php5pear ') in d:websitetest.php on line 2

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