时间:2021-07-01 10:21:17 帮助过:16人阅读
- <ol class="dp-xml"><li class="alt"><span><strong><font color="#006699"><span class="tag"><!--?</SPAN--><span class="tag-name">php</span></span></font></strong><span> </span></span></li><li class=""><span>$</span><span class="attribute"><font color="#ff0000">my_file</font></span><span>=@file('non_existent_file')or </span></li><li class="alt"><span>die("Failedopeningfile:errorwas'$php_errormsg'"); </span></li><li class=""><span>$</span><span class="attribute"><font color="#ff0000">value</font></span><span>=@$cache[$key]; </span></li><li class="alt"><span></span><span class="tag"><strong><font color="#006699">?></font></strong></span><span> </span></li></ol>
- <ol class="dp-xml"><li class="alt"><span><strong><font color="#006699"><span class="tag"><!--?</SPAN--><span class="tag-name">php</span></span></font></strong><span> </span></span></li><li class=""><span>$</span><span class="attribute"><font color="#ff0000">output</font></span><span>=`ls-al`; </span></li><li class="alt"><span>echo"</span><strong><font color="#006699"><span class="tag"><</span><span class="tag-name">pre</span><span class="tag">></span></font></strong><span>$output</span><strong><font color="#006699"><span class="tag"><!--</SPAN--><span class="tag-name">pre</span><span class="tag">></span></span></font></strong><span>"; </span></li><li class=""><span></span><span class="tag"><strong><font color="#006699">?></font></strong></span><span> </span></li></ol>
注:反引号运算符在激活了安全模式或者关闭了shell_exec()时是无效的。
加一/减一运算符:
++$a前加$a的值加一,然后返回$a。
$a++后加返回$a,然后将$a的值加一。
--$a前减$a的值减一,然后返回$a。
$a--后减返回$a,然后将$a的值减一。
这个跟c语言的自加,自减一样举个简单的例子加深一下
输出值为4
- <ol class="dp-xml"><li class="alt"><span><strong><font color="#006699"><span class="tag"><</span><span class="tag-name">html</span><span class="tag">></span></font></strong><span> </span></span></li><li class=""><span></span><strong><font color="#006699"><span class="tag"><</span><span class="tag-name">head</span><span class="tag">></span></font></strong><span> </span></li><li class="alt"><span></span><strong><font color="#006699"><span class="tag"><</span><span class="tag-name">title</span><span class="tag">></span></font></strong><span>php常量定义--阿涛随笔</span><strong><font color="#006699"><span class="tag"><!--</SPAN--><span class="tag-name">title</span><span class="tag">></span></span></font></strong><span> </span></li><li class=""><span></span><strong><font color="#006699"><span class="tag"><!--</SPAN--><span class="tag-name">head</span><span class="tag">></span></span></font></strong><span> </span></li><li class="alt"><span></span><strong><font color="#006699"><span class="tag"><</span><span class="tag-name">body</span><span class="tag">></span></font></strong><span> </span></li><li class=""><span> </span></li><li class="alt"><span></span><strong><font color="#006699"><span class="tag"><!--?</SPAN--><span class="tag-name">php</span></span></font></strong><span> </span></li><li class=""><span> </span></li><li class="alt"><span>$</span><span class="attribute"><font color="#ff0000">a</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">3</font></span><span>; </span></li><li class=""><span>$</span><span class="attribute"><font color="#ff0000">a</font></span><span>=++$a; </span></li><li class="alt"><span>echo$a."</span><strong><font color="#006699"><span class="tag"><</span><span class="tag-name">br</span><span class="tag">></span></font></strong><span>"; </span></li><li class=""><span> </span></li><li class="alt"><span>//</span></li></ol>
http://www.bkjia.com/PHPjc/446482.htmlwww.bkjia.comtruehttp://www.bkjia.com/PHPjc/446482.htmlTechArticle学习PHP时,你可能会遇到PHP运算符优先级问题,这里将介绍PHP运算符优先级问题的解决方法,在这里拿出来和大家分享一下。PHP支持一个错...