我简单的匹配abba 这样的4个连续的数字,里面使用了子表达式和反向引用,结果没有捕获到,真不知道为什么,我哪里写错了?<?php
header("Content-type:text/html;charset=utf-8");
$str="fdsafsdafsgfdag1223fa1551sdfassd3265";
$mypreg="/(\d)(\d)\2\1/";//匹配abba式的数字,即上面的1551
$mycon="这是数字";
$str=preg_replace($mypreg,$mycon,$str);
echo $str."<br/>";
header("Content-type:text/html;charset=utf-8");
$str="fdsafsdafsgfdag1223fa1551sdfassd3265";
$mypreg="/(\d)(\d)\2\1/";//匹配abba式的数字,即上面的1551
$mycon="这是数字";
$str=preg_replace($mypreg,$mycon,$str);
echo $str."<br/>";
$mycon="这是数字";
$str=preg_replace('/(\d)(\d)\2\1/',$mycon,$str);
echo $str."<br/>";
fdsafsdafsgfdag1223fa这是数字sdfassd3265<br/>但直接复制你的代码就不行
估计是你的编辑器有问题
在双引号中字符的转义符生效了
$a = "/(\d)(\d)\2\1/";
$b = '/(\d)(\d)\2\1/';
var_dump($a == $b);
var_dump($a, $b);bool(false) string(12) "/(\d)(\d)/" string(14) "/(\d)(\d)\2\1/" 要这样$a = "/(\d)(\d)\\2\\1/";
$b = '/(\d)(\d)\2\1/';
var_dump($a == $b);
var_dump($a, $b);bool(true) string(14) "/(\d)(\d)\2\1/" string(14) "/(\d)(\d)\2\1/" 所以你会看到一些正则表达式中会有一连串的 \
\\\、\\\\....
总之是不对就加一个
$mypreg='/(\d)\1{3}/i';
$mycon="这是数字";
echo $str."<br/>";
$str=preg_replace($mypreg,$mycon,$str);
echo $str."<br/>";因为PHP的\在双引号中会起转义作用