Detailed explanation of include include_once require require_once performance comparison in PHP_PHP tutorial

The article uses pictures and texts to introduce in detail the performance diagrams of include and include_once and require and require_once in PHP. Friends who need it can take a detailed look, but generally speaking, the performance of include_once and require_once is much better, especially when called multiple times. .

PHP Performance Optimization Issue 8 Functions, the performance comparison of include() and include_once() and require() and require_once() is mainly to compare the performance differences by obtaining the execution time of these four functions. The experiment uses Benchmark_Iterate type tools.

Test method
Load an existing file exist.php, call it 50 times through the Benchmark_Iterate class, obtain the execution time of each function and generate a curve graph.

Test code

The code is as follows

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代码如下

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require_once "Benchmark/Iterate.php"; $bench = new Benchmark_Iterate; function load_include(){     include 'exist.php'; } function load_require(){     require 'exist.php'; } function load_include_once(){     include_once 'exist.php'; } function load_require_once(){     require_once 'exist.php'; } $bench->run(50,"load_include"); //$bench->run(50,"load_require"); //$bench->run(50,"load_include_once"); //$bench->run(50,"load_require_once"); $result = $bench->get();

require_once "Benchmark/Iterate.php"; $bench = new Benchmark_Iterate; function load_include(){ include 'exist .php'; } function load_require(){ require 'exist.php'; } function load_include_once(){ include_once 'exist.php'; } function load_require_once(){ require_once 'exist.php'; } $bench->run(50,"load_include"); //$bench-> ;run(50,"load_require"); //$bench->run(50,"load_include_once"); //$bench->run(50,"load_require_once"); $result = $bench->get();

Test results
1, the execution time of using include() function to load files

Illustration: the average execution time of using include() function to load files is about 0.0013 seconds

2, the execution time of using include_once() function to load files

Illustration: the average execution time of using include_once() function to load files is 0.0011-0.0012 seconds

3. Execution time of using require function to load files

Illustration: The average execution time of using require() function to load files is 0.0012-0.0013 seconds

4. Using require_once() function Execution time of loading files

Solution: The average execution time of loading files using the require_once() function is 0.0011-0.0012 seconds

It can be seen from the above test results that the four functions of loading files The execution time is basically the same. The difference is that if a file is loaded multiple times, the include and require functions will be loaded multiple times, while the include_once and require_once functions will only be loaded once. Different from handling load failures at the same time, include() and include_once() generate a warning while require() and require_once() result in a fatal error.

Related instructions
include() and require() functions
The two structures are exactly the same except how to handle failures. include() produces a warning and require() results in a fatal error. In other words, use require() if you want to stop processing the page if a missing file is encountered. This is not the case with include() and the script will continue to run. Also make sure the appropriate include_path is set. Note that before PHP 4.3.5, syntax errors in include files did not cause the program to stop, but from this version onwards they will.

The order of searching for include files is first to search under the include_path relative to the current working directory, and then to search under the include_path relative to the directory where the currently running script is located. For example, include_path is ., the current working directory is /www/, and the script needs to include an include/a.php and there is an include "b.php" in the file, then the order of searching for b.php is first /www/, then is /www/include/. If the file name starts with ./ or ../, it will only be searched under the include_path relative to the current working directory.

When a file is included, the code contained in it inherits the variable scope of the include line. From that point on, any variables available in the calling file at that line are also available in the called file. However, all functions and classes defined in include files have global scope.

include_once() and require_once() functions
include_once() and require_once() statements include and run the specified file during script execution. This behavior is similar to include() and require() statements, the only difference is that if the code in the file is already included, it will not be included again. As the name of this statement implies, it will only be included once. include_once() and require_once() should be used when the same file may be included more than once during script execution, and you want to ensure that it is only included once to avoid problems such as function redefinition and variable reassignment.

http://www.bkjia.com/PHPjc/444722.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/444722.htmlTechArticleThe article uses pictures and texts to introduce in detail the include and include_once and require and require_once performance charts in PHP. If necessary Friends can look at it in detail, but generally speaking include_once and...