如何使用正则表达式删除最后一个特定的字符串？

Question

嗨，我有像下面的字符串，

$aa = "Ability: N/S,Session: Session #2: Tues June 14th - Fri June 24th (9-2:00PM),Time: 10:30am,cname: karthi";

$aa = "Ability: N/S,Session: Session #1: Tues May 31st - Fri June 10th (1-5:30PM),Time: #1 only: 1:30pm,cname: ravi";

$aa = "Ability: N/S,Session: Session #1: Tues May 31st - Fri June 10th (1-5:30PM),Time: #1 only: 1am,cname: mathi";

我需要编写单个正则表达式来从“，cname：”到最后删除特定字符串。 我需要输出像，

$aa = "Ability: N/S,Session: Session #2: Tues June 14th - Fri June 24th (9-2:00PM),Time: 10:30am";

    $aa = "Ability: N/S,Session: Session #1: Tues May 31st - Fri June 10th (1-5:30PM),Time: #1 only: 1:30pm";

    $aa = "Ability: N/S,Session: Session #1: Tues May 31st - Fri June 10th (1-5:30PM),Time: #1 only: 1am";

我怎么能在正则表达式中这样做？

Answer 1

尝试

/,cname:.*$/

并用空字符串替换。

$result = preg_replace('/,cname:.*$/', '', $aa);

在Regexr上看到它

Answer 2

你不需要正则表达式。 您可以使用strpos（）查找'，cname：'的索引，然后使用substr（）直到该索引。

<?php

$aa = "Ability: N/S,Session: Session #1: Tues May 31st - Fri June 10th (1-5:30PM),Time: #1 only: 1am,cname: mathi";
$pos = strpos($aa, ',cname:');
$bb = substr($aa, 0, $pos);
echo $bb, "\n";

但是如果你因为某种原因坚持使用正则表达式，你会想要使用preg_replace（） ：

<?php

$aa = "Ability: N/S,Session: Session #1: Tues May 31st - Fri June 10th (1-5:30PM),Time: #1 only: 1am,cname: mathi";
$bb = preg_replace('#,cname:.*$#', '', $aa);
echo $bb, "\n";

如果您不想修改字符串，可能需要使用preg_match（） ：

<?php

$aa = "Ability: N/S,Session: Session #1: Tues May 31st - Fri June 10th (1-5:30PM),Time: #1 only: 1am,cname: mathi";
if (preg_match('#^(.+),cname:.*$#', $aa, $match)) {
    echo $match[1], "\n";
}

Answer 3

/^(.*),cname:.*;$/

这个正则表达式生成的第1组（$ 1）将为您提供所需的结果。

Answer 4

如果您有多个,cname:...并且只想删除最后一个，请使用：

$aa= preg_replace('/,cname:.*?$/', '', $aa);