C＃版本的SQL LIKE [英] C# Version Of SQL LIKE

问题描述

有没有什么办法来搜索字符串的模式在C＃？

Is there any way to search patterns in strings in C#?

东西，如SQL LIKE将是非常有益的。

Something like Sql LIKE would be very useful.

推荐答案

普通EX pressions允许的一切， LIKE 允许，等等，但一个完全不同的语法。然而，由于规则 LIKE 是如此简单（其中％表示零或更多的字符和 _ 表示一个字符），无一不 LIKE 参数，并定期EX pressions是pssed在字符串中的前$ P $，我们可以创建一个普通的前pression，需要一个 LIKE 参数（如 abc_ef％*美元），并把它成等价的普通恩pression（如 \ Aabc.ef. * \ * USD \ Z ）：

Regular expressions allow for everything that LIKE allows for, and much more, but have a completely different syntax. However, since the rules for LIKE are so simple(where % means zero-or-more characters and _ means one character), and both LIKE arguments and regular expressions are expressed in strings, we can create a regular expression that takes a LIKE argument (e.g. abc_ef% *usd) and turn it into the equivalent regular expression (e.g. \Aabc.ef.* \*usd\z):

@"\A" + new Regex(@"\.|\$|\^|\{|\[|\(|\||\)|\*|\+|\?|\\").Replace(toFind, ch => @"\" + ch).Replace('_', '.').Replace("%", ".*") + @"\z"

这是我们可以建立一个赞（）方法：

From that we can build a Like() method:

public static class MyStringExtensions
{
  public static bool Like(this string toSearch, string toFind)
  {
    return new Regex(@"\A" + new Regex(@"\.|\$|\^|\{|\[|\(|\||\)|\*|\+|\?|\\").Replace(toFind, ch => @"\" + ch).Replace('_', '.').Replace("%", ".*") + @"\z", RegexOptions.Singleline).IsMatch(toSearch);
  }
}

因此​​：

bool willBeTrue = "abcdefg".Like("abcd_fg");
bool willAlsoBeTrue = "abcdefg".Like("ab%f%");
bool willBeFalse = "abcdefghi".Like("abcd_fg");

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