PHP中include和require的区别实例分析
author:一佰互联 2019-04-25   click:163

先编辑command.php文件

echo "hello".PHP_EOL;

然后编辑console.php文件

for($i=1;$i<=3;++$i){
	require "command1.php";
}

原本想要包含并执行这个echo,没想到写错了文件名,如果是require,会报出这样的错误:

Warning: require(command1.php): failed to open stream: No such file or directory in console.php on line 4

Fatal error: require(): Failed opening required "command1.php" (include_path=".") in console.php on line 4
PHP Warning: require(command1.php): failed to open stream: No such file or directory in console.php on line 4
PHP Fatal error: require(): Failed opening required "command1.php" (include_path=".") in console.php on line 4

如果把require改为include

for($i=1;$i<=3;++$i){
	include "command1.php";
}

会报出这样的错误:

Warning: include(command1.php): failed to open stream: No such file or directory in console.php on line 4

Warning: include(): Failed opening "command1.php" for inclusion (include_path=".") in console.php on line 4

Warning: include(command1.php): failed to open stream: No such file or directory in console.php on line 4

Warning: include(): Failed opening "command1.php" for inclusion (include_path=".") in console.php on line 4

Warning: include(command1.php): failed to open stream: No such file or directory in console.php on line 4

Warning: include(): Failed opening "command1.php" for inclusion (include_path=".") in console.php on line 4
PHP Warning: include(command1.php): failed to open stream: No such file or directory in console.php on line 4
PHP Warning: include(): Failed opening "command1.php" for inclusion (include_path=".") in console.php on line 4
PHP Warning: include(command1.php): failed to open stream: No such file or directory in console.php on line 4
PHP Warning: include(): Failed opening "command1.php" for inclusion (include_path=".") in console.php on line 4
PHP Warning: include(command1.php): failed to open stream: No such file or directory in console.php on line 4
PHP Warning: include(): Failed opening "command1.php" for inclusion (include_path=".") in console.php on line 4

如果使用require_once或者include_once,只要包含路径正确,那么循环只执行一次。

总结:

使用require,如果文件没有包含成功,就会报出一个fatal error,整个程序就中止了。

使用include,如果文件没有包含成功,就会报出一个普通的warning,之后的代码仍会执行。

如果你的Web程序使用了MVC这种对文件包含强依赖的设计方法,请使用require_once。