内容简介：翻译自：https://stackoverflow.com/questions/14079459/include-external-php-files
我正在使用一些 PHP 代码,如数据库连接,这对所有页面都很常见,所以我创建了一个包含php代码的php文件,然后我将这个文件包含在我的HTML代码中,
所以我想知道更好的方法来包含php文件,更好的替代include函数.
我的示例代码在这里
<?php
include "check_timeout.php";
include "connect_to_db.php";
?>
<html>
<head>
<title>Example</title>
</head>
<body>
<?php
mysql_close($con);
?>
</body>
</html>
先感谢您.
您有4个选项可供选择.
包括’yourfile.php’;
include_once’yourfile.php’;
要求’yourfile.php’;
require_once’yourfile.php’;
当然你也可以用“代替”.
他们都会做同样的事情,除了微小的差异.
如果yourfile.php不存在,则包含的将忽略该事实,并且您的php页面将继续 – 没有任何致命错误.
另一方面,需要的会产生致命的错误.
如果你知道那个文件在那里,你选择哪一个没什么区别.
至于带有_once后缀的选项,嗯,与它们的非_once后固定对应物相比,它们往往更慢.因为当你使用include_once或require_once时,PHP会做一些额外的工作来确保那些文件真正包含在ONCE中 – 保护你免受可能的双重包含情况,如果你不小心编码和许多文件使用许多包含你可能会遇到两次包含相同文件的情况.好吧,_once选项会阻止它.而且检查会带来一些处理成本.
我还注意到你已经使用了“而不是”用于文件分隔符.没有理由选择“over”,除非你在文件中引用变量名称,例如
$thefile =’yourfile.php;
包括“$thefile”;
那么从这4个中选出哪些？
这一切都取决于,如果你认为你确实需要强制_once问题,那么你选择include_once或require_once,如果你认为不需要,那么你选择include或require.至于include vs require,如果你的文件由于某种原因无法访问,那么你是否希望你的PHP脚本死掉或继续前进.
如果您对某些速度测试感到好奇,这里有一个链接供您查看.
http://php.net/manual/en/function.require-once.php我也在主题上找到了这个.
Understanding the difference between require and include According to the PHP manual, require and include “are identical in every way except how they handle failure.” However, further reading of the manual suggests another very subtle difference that impacts performance. When you use the require keyword, the named file is read in, parsed, and compiled when the file using the require keyword is compiled. When a file containing the include keyword is compiled, the named file is not read in, parsed, and compiled initially. Only when that line of code is executed is the file read, parsed and compiled. Only use the require keyword if you know you will always need that named file in the current script. If you might use its functions, use include instead. PHP opens up all files that are required, but only opens included files as needed. Additionally, you should also consider using require_once and include_once in place of require and include respectively. In practice, it is more likely that you actually want the functionality provided by the require_once and include_once functions, even though it is much more common to use the require and include keywords respectively. Refer to the following PHP manual pages for more information: include, include_once source: 07001
翻译自：https://stackoverflow.com/questions/14079459/include-external-php-files
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