php - 大字符串中某个字符串的 preg_replace

Question

我有一个大字符串，其中包含mysite/tim/here-is-something.html其他 url 模式，例如mysite/a/some-thing.html. 现在我想将第一个模式全部更改-为+并保持所有其他模式不变。

有谁知道如何处理这个问题？

感谢您的任何建议！

Answer 1

$pattern = '!((mysite/tim/)[-\w\.]*)+(?=((mysite/a/)+)|(\s+|\n))!';
$html = 'mysite/tim/here-is-something.html   mysite/tim/here-is-something.html  mysite/a/here-is-something.html mysite/tim/here-is-som-ething.html  mysite/a/here-is-something.html mysite/tim/he-re-is-so-m-eth-ing.html  mysite/a/here-is-something.html  mysite/a/here-is-something.html mysite/tim/here-is-something.html  mysite/tim/here-is-something.html 
mysite/tim/here-is-something.html ';
preg_match_all($pattern,$html, $match);
//print_r($match);
foreach ($match[0] as $value) {
    $modified_value=str_replace("-","+", $value);
    $html=str_replace($value,$modified_value,$html);
}
print_r ($html);

输出：

mysite/tim/here+is+something.html mysite/tim/here+is+something.html mysite/a/here-is-something.html mysite/tim/here+is+som+ething.html mysite/a/here-is-something.html mysite/tim/he+re+is+so+m+eth+ing.html mysite/a/here-is-something.html mysite/a/here-is-something.html mysite/tim/here+is+something.html mysite/tim/here+is+something.html mysite/tim/here+is+something.html

找到的匹配项：

match[0] => Array
        (
            [0] => mysite/tim/here-is-something.html
            [1] => mysite/tim/here-is-something.html
            [2] => mysite/tim/here-is-som-ething.html
            [3] => mysite/tim/he-re-is-so-m-eth-ing.html
            [4] => mysite/tim/here-is-something.html
            [5] => mysite/tim/here-is-something.html
            [6] => mysite/tim/here-is-something.html
        )

Answer 2

听起来您已经解决了它，但问题被巧妙地分为 preg_match 和 str_replace。preg_match 可能比您描述的将元素加载到数组中更灵活，但它也需要了解正则表达式才能理解它的工作原理。

preg_replace 不能用于一步实现此结果，因为它无法处理灵活长度的正向后视。它可以替换一次出现 - 但不能替换多次出现（除非它被放入 while 循环，这将是另一种选择）。

<?
$strings = array("mysite/tim/here-is-something.html",
                 "mysite/a/some-thing.html");

foreach ($strings as $string) {
  if (preg_match("#^(mysite/tim/)(.*)#",$string,$matches)) {
    print "Changed string: $string\nto: ";
    print $matches[1].str_replace("-","+",$matches[2])."\n";
  } else {
    print "Didn't change string: $string\n";
  }
}

输出：

Changed string: mysite/tim/here-is-something.html
to: mysite/tim/here+is+something.html
Didn't change string: mysite/a/some-thing.html