正则表达式找不到所有匹配项

Question

编辑：我有一个string str = "where dog is and cats are and bird is bigger than a mouse" ，并要提取之间的单独子where和and ， and而and ， and和句子的末尾。 结果应该是： dog is ， cats are ， bird is bigger than a mouse 。 （示例字符串可能包含where and ect之间的任何子串。）

List<string> list = new List<string>();
string sample = "where dog is and cats are and bird is bigger than a mouse";
MatchCollection matches = Regex.Matches(sample, @"where|and\s(?<gr>.+)and|$");
foreach (Match m in matches)
  {
     list.Add(m.Groups["gr"].Value.ToString());
  }

但它不起作用。 我知道正则表达不对，所以请帮我纠正。 谢谢。

Answer 1

怎么样"\\w+ is"

  List<string> list = new List<string>();
string sample = "where dog is and cat is and bird is";
MatchCollection matches = Regex.Matches(sample, @"\w+ is");
foreach (Match m in matches)
{
    list.Add(m.Value.ToString());
}

示例： https ： //dotnetfiddle.net/pMMMrU

Answer 2

使用大括号来修复| 和一个看守：

using System;
using System.Text.RegularExpressions;

public class Solution
{
    public static void Main(String[] args)
    {
        string sample = "where dog is and cats are and bird is bigger than a mouse";
        MatchCollection matches = Regex.Matches(sample, @"(?<=(where|and)\s)(?<gr>.+?)(?=(and|$))");
        foreach (Match m in matches)
        {
            Console.WriteLine(m.Value.ToString());
        }
    }
}

小提琴： https ： //dotnetfiddle.net/7Ksm2G

输出：

dog is 
cats are 
bird is bigger than a mouse

Answer 3

您应该使用Regex.Split()方法而不是Regex.Match() 。

    string input = "where dog is and cats are and bird is bigger than a mouse";
    string pattern = "(?:where|and)";  
    string[] substrings = Regex.Split(input, pattern);
    foreach (string match in substrings)
    {
         Console.WriteLine("'{0}'", match);
    }

这将分为文字where和and 。

Ideone演示