5

我想创建一种匹配字符串的方法，例如

abc(xyz)
abc
abc(xyz)[123]

其中每个括号是一个可选单元。我最想拥有的是

preg_match_all('complicated regex', $mystring, $matches);

$matches返回以下内容：

  • 如果$mystring= abc(xyz)[123]R给$matches=array(0 => "abc", 1=> "xyz", 2=> "123", 3=> "R")
  • 如果$mystring= abc(xyz)R给$matches=array(0 => "abc", 1=> "xyz", 2=> "", 3=> "R")
  • 如果$mystring= abc[123]R给$matches=array(0 => "abc", 1=> "", 2=> "123", 3=> "R")
  • 如果$mystring= abc(xyz)[123]给$matches=array(0 => "abc", 1=> "xyz", 2=> "123", 3=> "")
  • 如果$mystring= abc给$matches=array(0 => "abc", 1=> "", 2=> "", 3=> "")

我希望你明白这一点。我尝试如下：

preg_match_all("/([a-z]*)(\([a-zA-Z]\))?(\[\w\])?/", "foo(dd)[sdfgh]", $matches)

其中matches[0]是

Array
(
    [0] => foo
    [1] => 
    [2] => dd
    [3] => 
    [4] => 
    [5] => sdfgh
    [6] => 
    [7] => 
)

为什么我会得到额外的空匹配？如何避免他们得到我需要的结果（在matches或matches[0]......）。

4

6 回答 6

1

怎么样：

/^(\w*)(?:\((\w*)\))?(?:\[(\w*)\])(\w*)?$/

用法：

preg_match_all("/^(\w*)(?:\((\w*)\))?(?:\[(\w*)\])(\w*)?$/", "abc[123]R", $matches); 
print_r($matches);

输出：

Array
(
    [0] => Array
        (
            [0] => abc[123]R
        )

    [1] => Array
        (
            [0] => abc
        )

    [2] => Array
        (
            [0] => 
        )

    [3] => Array
        (
            [0] => 123
        )

    [4] => Array
        (
            [0] => R
        )

)

解释：

The regular expression:

(?-imsx:^(\w*)(?:\((\w*)\))?(?:\[(\w*)\])(\w*)?$)

matches as follows:

NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  ^                        the beginning of the string
----------------------------------------------------------------------
  (                        group and capture to \1:
----------------------------------------------------------------------
    \w*                      word characters (a-z, A-Z, 0-9, _) (0 or
                             more times (matching the most amount
                             possible))
----------------------------------------------------------------------
  )                        end of \1
----------------------------------------------------------------------
  (?:                      group, but do not capture (optional
                           (matching the most amount possible)):
----------------------------------------------------------------------
    \(                       '('
----------------------------------------------------------------------
    (                        group and capture to \2:
----------------------------------------------------------------------
      \w*                      word characters (a-z, A-Z, 0-9, _) (0
                               or more times (matching the most
                               amount possible))
----------------------------------------------------------------------
    )                        end of \2
----------------------------------------------------------------------
    \)                       ')'
----------------------------------------------------------------------
  )?                       end of grouping
----------------------------------------------------------------------
  (?:                      group, but do not capture:
----------------------------------------------------------------------
    \[                       '['
----------------------------------------------------------------------
    (                        group and capture to \3:
----------------------------------------------------------------------
      \w*                      word characters (a-z, A-Z, 0-9, _) (0
                               or more times (matching the most
                               amount possible))
----------------------------------------------------------------------
    )                        end of \3
----------------------------------------------------------------------
    \]                       ']'
----------------------------------------------------------------------
  )                        end of grouping
----------------------------------------------------------------------
  (                        group and capture to \4 (optional
                           (matching the most amount possible)):
----------------------------------------------------------------------
    \w*                      word characters (a-z, A-Z, 0-9, _) (0 or
                             more times (matching the most amount
                             possible))
----------------------------------------------------------------------
  )?                       end of \4 (NOTE: because you are using a
                           quantifier on this capture, only the LAST
                           repetition of the captured pattern will be
                           stored in \4)
----------------------------------------------------------------------
  $                        before an optional \n, and the end of the
                           string
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------
于 2013-05-16T11:47:42.907 回答
1

你会得到如此多的结果，因为你的比赛开始了 8 次。所有字符串（包括空字符串）与正则表达式的第一个非可选部分匹配：([a-z]*).

更正的正则表达式：

preg_match_all("/^([a-z]*)(\([a-zA-Z]*\))?(\[\w*\])?$/", "foo(ddd)[sdfgh]", $matches);

编辑（排除主题第二部分中的括号）所以我们想要'ddd'而不是'(ddd)'：

此正则表达式使用“非捕获模式”(?: ... )来标记主题的可选部分，而不是在匹配数组中捕获它。

preg_match_all("/^([a-z]*)(?:\(([a-zA-Z]*)\))?(\[\w*\])?$/", "foo(ddd)[sdfgh]", $matches);

有趣的部分是：(?:\(([a-zA-Z]*)\))?.

  • 第一个括号(?:标记非捕获子模式的开始
  • 第二个括号\(是转义的文字括号
  • 第三个(标记标准捕获子模式的开始

只有第三个括号对的内容会显示在 $matches 数组中。

于 2013-05-16T10:32:36.060 回答
0

可选的最后一个字母会稍微偏离结果，但这个表达式将覆盖它：

function doit($s)
{
        echo "==== $s ====\n";
        preg_match_all('/(\w+) # first word
                (?: \(([^)]+)\) )? # match optional (xyz)
                (?: \[([^]]+)\])? # match optional [123]
                (\w?) # match optional last char
                /x', $s, $matches, PREG_SET_ORDER);

        print_r($matches);
}

doit('abc(xyz)[123]R xyz(123)');
doit('abc(xyz)R');
doit('abc[123]R');
doit('abc(xyz)[123]');

结果

==== abc(xyz)[123]R xyz(123) ====
Array
(
    [0] => Array
        (
            [0] => abc(xyz)[123]R
            [1] => abc
            [2] => xyz
            [3] => 123
            [4] => R
        )

    [1] => Array
        (
            [0] => xyz(123)
            [1] => xyz
            [2] => 123
            [3] => 
            [4] => 
        )

)
==== abc(xyz)R ====
Array
(
    [0] => Array
        (
            [0] => abc(xyz)R
            [1] => abc
            [2] => xyz
            [3] => 
            [4] => R
        )

)
==== abc[123]R ====
Array
(
    [0] => Array
        (
            [0] => abc[123]R
            [1] => abc
            [2] => 
            [3] => 123
            [4] => R
        )

)
==== abc(xyz)[123] ====
Array
(
    [0] => Array
        (
            [0] => abc(xyz)[123]
            [1] => abc
            [2] => xyz
            [3] => 123
            [4] => 
        )

)
于 2013-05-16T12:22:47.983 回答
0

一种在没有空项目的情况下获得所需内容的方法：

$pattern = '~(?|\[(\w*+)]|\(([a-zA-Z]*+)\)|\b([a-z]*+)\b)~';
preg_match_all($pattern, 'foo(dd)[sdfgh]', $matches);
print_r($matches[1]);

注意：这可以匹配括号中的空字符串，为避免它们，将 * 替换为 +

于 2013-05-16T11:05:23.210 回答
0

为什么不使用preg_split()？

$string = 'abc(xyz)[123]';
$array = preg_split('/\]?\(|\)\[?|\[|\]/', $string);
print_r($array);

在线演示

于 2013-05-16T10:35:07.067 回答
0

尝试使用这个简单的正则表达式：

[a-zA-Z0-9]+

使用preg_match_all时，它将查找与给定模式匹配的所有子字符串，如果它们之间存在大括号、方括号或其他字符，则将它们分组。

preg_match_all("/[a-zA-Z0-9]+/", "foo(dd)[sdfgh]", $matches);
print_r($matches);

Array
(
    [0] => Array
        (
            [0] => foo
            [1] => dd
            [2] => sdfgh
        )

)

如果由于某种原因您需要分别使用大括号和方括号，则可以使用如下分组：

([\(\)\[\]])?([a-zA-Z0-9]+)([\(\)\[\]])?

preg_match_all("/([\(\)\[\]])?([a-zA-Z0-9]+)([\(\)\[\]])?/", "foo(dd)[sdfgh]", $matches); 
print_r($matches);

Array
(
    [0] => Array
        (
            [0] => foo(
            [1] => dd)
            [2] => [sdfgh]
        )

    [1] => Array
        (
            [0] => 
            [1] => 
            [2] => [
        )

    [2] => Array
        (
            [0] => foo
            [1] => dd
            [2] => sdfgh
        )

    [3] => Array
        (
            [0] => (
            [1] => )
            [2] => ]
        )

)
于 2013-05-16T10:53:42.563 回答