include和require的区别

首先准备一个要包含的文件a.php，文件内容如下

<?php $a = 1; ?>

测试require_once，内容如下

<?php
for($i=1; $i<=10;$i++)  {
    require_once('a.php');
    echo $a++;
}

输出结果如下，因为只有第一次包含有效，以后的包含就都无效了

12345678910

测试require，内容如下

<?php
for($i=1; $i<=10;$i++)  {
    require('a.php');
    echo $a++;
}

输出结果如下，每次都要执行包含，所以输出都是1

1111111111

把require和require_once换成include和include_once执行的效果是一样的

2. include和require之间的区别只是对错误的处理方式不一样

require

<?php
require('b.php');
echo "contiue code \n";

执行结果如下，continue code这句话并没有输出，说明require包含文件如果遇到错误，后面的代码就不执行了

PHP Warning:  require(b.php): failed to open stream: No such file or directory in /home/lxy/htdocs/test.php on line 2
PHP Fatal error:  require(): Failed opening required 'b.php' (include_path='.:') in /home/lxy/htdocs/test.php on line 2

include

<?php
include('b.php');
echo "contiue code \n";

执行结果如下，continue code输出了

PHP Warning:  include(b.php): failed to open stream: No such file or directory in /home/lxy/htdocs/test.php on line 3
contiue code 
PHP Warning:  include(): Failed opening 'b.php' for inclusion (include_path='.:') in /home/lxy/htdocs/test.php on line 3