Introduction to the usage of php include and require_PHP tutorial

There are two ways to reference files: require and include. The two methods provide different usage flexibility.

require is used like require("MyRequireFile.php"); . This function is usually placed at the front of the PHP program. Before the PHP program is executed, it will first read in the file specified by require and make it a part of the PHP program web page. Commonly used functions can also be introduced into web pages in this way.

The functions of include() and require() are basically the same (include), but there are some differences in usage. include() is a conditional inclusion function, while require() is an unconditional inclusion function. For example, in the following code, if the variable $a is true, the file a.php will be included:

The code is as follows

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if($a){ include("a.php"); }

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if($a){

include("a.php");

}

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if($a){ require("a.php"); }

The use method of include is include("MyIncludeFile.php");. This function is generally placed in the processing part of flow control. The PHP program web page only reads the include file when it reads it. In this way, the process of program execution can be simplified.

And require() is different from include(). No matter what value $a takes, the following code will include the file a.php into the file:

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The code is as follows

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test.php include (”test999.php”); echo “abc”; ?> test2.php require (”test999.php”) echo “abc”; ?>

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if($a){

require("a.php");
}

In terms of error handling, use the include statement. If an include error occurs, the program will skip the include statement. Although the error message will be displayed, the program will continue to execute! But require will give you a fatal error.

Using an example, write two php files named test1.php and test2.php. Note that there should not be a file named test999.php in the same directory.

The code is as follows

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test.php include ("test999.php"); echo “abc”; ?> test2.php require ("test999.php") echo “abc”; ?> Browse the first file. Because the test999.php file was not found, we saw the error message. At the same time, abc was displayed below the error message. What you saw may be similar to the following: Warning: include(test1aaa.php) [function.include]: failed to open stream: No such file or directory in D:WebSitetest.php on 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 the test999.php file was not found, we saw the error message. However, abc was not displayed below the error message. What you saw may be similar to the following: Warning: require(test1aaa.php) [function.require]: failed to open stream: No such file or directory in D:WebSitetest.php on line 2 Fatal error: require() [function.require]: Failed opening required ‘test1aaa.php’ (include_path=’.;C:php5pear’) in D:WebSitetest.php on line 2 http://www.bkjia.com/PHPjc/632228.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/632228.htmlTechArticleThere are two ways to reference files: require and include. The two methods provide different usage flexibility. The usage method of require is as require(MyRequireFile.php);. This function is usually placed...