Question

考虑以下句子：

苹果是2公斤苹果香蕉芒果是2千克苹果苹果是6公斤
香蕉香蕉香蕉是6kg

鉴于“苹果”，“香蕉”和“芒果”是唯一的果实，提取出现在句子开头的水果名称的正则表达式是什么？

我写了这个正则表达式（https://regex101.com/r/fY8bK1/1）：

^(apple|mango|banana) is (\d+)kg$

但这仅在句子中有单个水果时匹配。

如何提取所有水果名称？

所有4个句子的预期输出应为：

apple，2
  苹果香蕉芒果，2
  苹果苹果，6
  香蕉香蕉香蕉，6

Answer 1

您可以使用这样的分组：

^((?:apple|mango|banana)(?:\s+(?:apple|mango|banana))*) is (\d+)kg$

请参阅regex demo

(?:...)是捕获（(...)）组内的非捕获组，以免在输出中造成混乱。

((?:apple|mango|banana)(?:\s+(?:apple|mango|banana))*)组匹配：

(?:apple|mango|banana) - 使用替换|运算符分隔的备用列表中的任何值。如果您打算仅匹配整个单词，请将\b放在子模式的两端。
(?:\s+(?:apple|mango|banana))*匹配0个或更多个序列...
- \s+ - 一个或多个空格
- (?:apple|mango|banana) - 任何替代方案。

段：

＆＃13;

var re = /^((?:apple|mango|banana)(?:\s+(?:apple|mango|banana))*) is (\d+)kg$/gm; 
var str = 'apple is 2kg\napple banana mango is 2kg\napple apple apple is 6kg\nbanana banana banana is 6kg';
var m;
 
while ((m = re.exec(str)) !== null) {
    document.write(m[1] + "," + m[2] + "<br/>");
}

document.write("<b>appleapple is 2kg</b> matched: " + 
     /^((?:apple|mango|banana)(?:\s+(?:apple|mango|banana))*) is (\d+)kg$/.test("appleapple is 2kg"));

＆＃13;

Answer 2

试试这个

var re = /^((?:(?:apple|banana|mango)(?= ) ?)+) is (\d+)kg$/gm;

re.exec('apple banana mango is 2kg');
// ["apple banana mango is 2kg", "apple banana mango", "2"]

这与其他答案的不同之处是什么？水果选项之后的(?= ) ?强制空格作为下一个字符，但除非有更多水果（或者你将分开两倍），否则不会捕获它。

在while循环中使用它可以从多行字符串中获取所有结果。

这里的gm标志允许此 RegExp 使用re.exec多次应用于同一 String ，其中新行匹配{{1 }}。但是，$^标记会导致g的行为不同。

如果您希望对每个字符串进行独立测试，可以继续使用str.match或删除这些标记并使用re.exec代替

str.match

Answer 3

/^(((apple|mango|banana)\s*)+) is (\d+)kg$/$1,$4/gm

DEMO：https://regex101.com/r/sA4aW7/2

所以你从这里开始，其中一个：

(apple|mango|banana)

让我们把最终的空白分开重复：

(apple|mango|banana)\s*

和所有（至少一个）重复：

((apple|mango|banana)\s*)+

需要添加一个额外的组，因为您希望单个组捕获该批次：

(((apple|mango|banana)\s*)+)

添加此点，$1（最外面的组）将包含“香蕉香蕉香蕉......”;第四个你的体重。添加您自己的?:以避免捕获内部群组if you like。

Answer 4

^((?:apple|mango|banana| )+) is (\d+)kg\s?$/gmi

<强>样本

https://regex101.com/r/dO1rR7/1

<强>解释

^((?:apple|mango|banana| )+) is (\d+)kg\s?$/gmi

^ assert position at start of a line
1st Capturing group ((?:apple|mango|banana| )+)
    (?:apple|mango|banana| )+ Non-capturing group
        Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
        1st Alternative: apple
            apple matches the characters apple literally (case sensitive)
        2nd Alternative: mango
            mango matches the characters mango literally (case sensitive)
        3rd Alternative: banana
            banana matches the characters banana literally (case sensitive)
        4th Alternative:  
             matches the character  literally
 is matches the characters  is literally (case sensitive)
2nd Capturing group (\d+)
    \d+ match a digit [0-9]
        Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
kg matches the characters kg literally (case sensitive)
\s? match any white space character [\r\n\t\f ]
    Quantifier: ? Between zero and one time, as many times as possible, giving back as needed [greedy]
$ assert position at end of a line
g modifier: global. All matches (don't return on first match)
m modifier: multi-line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])

匹配此字符串的正则表达式是什么？

4 个答案: