https://jackxiang.com/index.php zh-cn https://jackxiang.com/post// jack <xdy108@126.com> Mon, 22 Sep 2014 06:39:56 +0000 https://jackxiang.com/post// $handle = popen($command, "r");
        do {
            $excuteResult = fread($handle, 2024);
            if (strlen($excuteResult) == 0) {
                pclose($handle); //关闭pipe
                break;
            }
            $excuteResultAll .= $excuteResult;
        } while (true);
//这儿用到的$excuteResultAll 变量，下面还要用，防止污染，则需要给NULL值清空，用unset后需要再定义一次相同的变量，否则会出现：
Undefined variable: excuteResultAll in /data/htdocs/jackxiang.com/index.php on line 354
        do {
            $excuteResult = fread($handle, 2024);
            if (strlen($excuteResult) == 0) {
                pclose($handle); //关闭pipe
                break;
            }
            $excuteResultAll .= $excuteResult;
        } while (true);

______________________________小demon实践如下：______________________________
php null.php
<?php
$foo = "";
$foo = "jack";
unset($foo);
$foo .= "xiang";
$vars = get_defined_vars();

通过unset后，$foo变量用点连接时运行如下：
[22-Sep-2014 14:29:59 Asia/Shanghai] PHP Notice:  Undefined variable: foo in /tmp/null.php on line 6
[foo] => xiang
而不用unset而用NULL后：
<?php
$foo = "";
$foo = "jack";
$foo = NULL;
//unset($foo);
$foo .= "xiang";
$vars = get_defined_vars();
print_r($vars);
解决了这个变量的问题：
[foo] => xiang

说明这样做是可行的，完毕。 ]]> https://jackxiang.com/post//#blogcomment <user@domain.com> Thu, 01 Jan 1970 00:00:00 +0000 https://jackxiang.com/post//#blogcomment