我正在准备一个字符串，用作目录列表。我正在处理用户输入的标题，需要删除除字母和数字外的所有标题，然后用_替换空格。。我已经能够用preg_replace接近这一点，但目前没有时间学习Regex的来龙去脉。
下面是字符串=This is a -string- that has /characters & other stuff! Let's filter it的一个示例。我拍摄的目的是：this_is_a_string_that_has_characters_other_stuff_lets_filter_it
我能够接近这个代码，但字符被删除的地方会留下后面的空格。结果是两双，这是可以接受的，但不是我想要的。
如有任何帮助，我们将不胜感激。这是我的尝试：
<?php
$string = " This is a -string- that has /characters & other stuff! Let's filter it?";
$cleansedstring = trim($string);
$cleansedstring = strtolower($cleansedstring);
$cleansedstring = preg_replace('/[^ 'w]+/', '', $cleansedstring);
$cleansedstring = preg_replace('['s]', '_', $cleansedstring);
echo $cleansedstring;
?>
更新这是我从这里的一些建议中发现的，看起来很干净，并输出了我拍摄的字符串。。改进建议？
$string = " This is a -string- _that has /characters & other stuff! Let's filter it?23";
$cleansedstring = trim($string);
$cleansedstring = strtolower($cleansedstring);
$cleansedstring = preg_replace('/[^ 'pL 'pN]/', '', $cleansedstring);
$cleansedstring = preg_replace('['s+]', '_', $cleansedstring);
echo $cleansedstring;
用于删除不需要的字符的正则表达式不应该有+，而检查空格的正则表达式后面需要+。
这也有效：
$s = "This is a -string- that has /characters & other stuff! Let's filter it";
echo "ORIG: [{$s}]<br />";
$s = preg_replace("/[^0-9a-zA-Z's]/","",$s);
$s = preg_replace("/'s['s]+/"," ",$s);
$s = preg_replace("/'s/","_",$s);
$s = strtolower($s);
echo "NEW: [{$s}]<br />";
// output is
// ORIG: [This is a -string- that has /characters & other stuff! Let's filter it]
// NEW: [this_is_a_string_that_has_characters_other_stuff_lets_filter_it]
试试这个：
<?php
$string = " This is a -string- that has /characters & & other stuff! Let's filter it?";
$cleanstring = strtolower(trim(preg_replace('#'W+#', '_', $string), '_'));
这里有一个我稍微修改过的旧函数，使用下划线：
public function make_url_friendly($string)
{
$string = trim($string);
// weird chars to nothing
$string = preg_replace('/('W'B)/', '', $string);
// whitespaces to underscore
$string = preg_replace('/['W]+/', '_', $string);
// dash to underscore
$string = str_replace('-', '_', $string);
// make it all lowercase
$string = strtolower($string);
return $string;
}
这应该可以满足的需要